Three chapters (docs/latex/), sourced from the real project docs
(BOM.md, PHYSICAL_REALIZATION.md, ARCHITECTURE_ANALYSIS.md,
experiments.log) -- no invented numbers:
- hardware.tex: board components, DDR3/FPGA/flash/ESP32, real pinout,
SPI protocol, boot procedure.
- architecture.tex: packed INT8 MAC core, N=8 hybrid systolic
architecture (shared-weight broadcast), hierarchical arbiter,
result writeback, why N=8 is the DDR3-bandwidth-bound sweet spot.
- tests_timing.tex: verification methodology, real functional test
results table, full real P&R signoff history (N=2 through N=16),
the definitive N=8 signoff (WNS=0.000ns), and an honestly-caveated
ESP32-S3 comparison (real historical ECP5 measurement vs. the
superseded, never-verified Artix-7 projection).
main.tex ties the three together as report chapters.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01MUG92aM9m68TRc4rG55BcC
New n8_system_ddr3_top.v: a real, permanent, named top-level (not a
build-time -generic override), byte-for-byte the same RTL as
n16_system_ddr3_top.v with N_GROUPS defaulting to 2. Real, full P&R
under this file's own name reproduces EXP-0095's own generic-override
result exactly: WNS=0.000ns, WHS=+0.017ns, 0 failing setup endpoints,
64 DSP48E1/26.7%, 12535 LUTs/19.77%.
New tb_n8_system_ddr3.v (real DDR3-model methodology, adapted from
tb_n16_system_ddr3.v, M=16 positions covering every one of the 2
groups x 4 PEs x 2 lanes exactly once): real functional xsim, 16/16
PASS, 0 errors -- closes the real functional-verification gap this
specific N previously had.
N=8 is now BOTH functionally verified AND timing-closed under its own
permanent name -- the real, definitive deployment target. N=2 kept as
a documented, valid fallback; N=16 kept as documented, functionally-
verified-but-not-timing-closed future work, not abandoned.
docs/PHYSICAL_REALIZATION.md, docs/ARCHITECTURE_ANALYSIS.md,
docs/PINOUT.md updated to reflect N=8 as the current real signoff.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01MUG92aM9m68TRc4rG55BcC
Fixed a real, previously-untested N_GROUPS=1 edge case in
neural_director_grouped.v (bare $clog2(N_GROUPS) invalid for
N_GROUPS=1, same class of bug sdram_arbiter_n.v's own SELW guard
already handles -- applied the same fix here and in
n16_system_ddr3_top.v's own job_out_group_w wire).
Real synth_design -generic N_GROUPS=<n> P&R sweep (same RTL/arbiter as
EXP-0094's real N=16 result):
N=4 (N_GROUPS=1): WNS=-0.005ns, 2 failing endpoints
N=8 (N_GROUPS=2): WNS=0.000ns, 0 failing endpoints -- REALLY CLOSED
N=16 (N_GROUPS=4): WNS=-0.338ns, 60 failing endpoints (EXP-0094)
N=8 is a real, new, closed P&R signoff -- 8x N=2's parallelism with
the same already-verified systolic RTL. Answers the user's own
question directly: the design does not fail until somewhere between
N=8 and N=16, not at N=4 or N=8.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01MUG92aM9m68TRc4rG55BcC
Same RTL, real Vivado strategy directives (Explore/ExtraNetDelay_high/
AggressiveExplore, zero RTL risk): WNS -0.646ns -> -0.338ns, TNS
-97.5ns -> -5.3ns, failing endpoints 771 -> 60. Remaining bottleneck
confirmed intrinsic (84% logic delay, DSP48E1->CARRY4 path inside
neural_processor_packed.v, recurring per-PE) -- unlikely to shrink
further via P&R strategy alone.
Cumulative: two safe fixes (hierarchical arbiter + directive tuning)
close ~89% of the original TNS gap and ~63% of WNS, neither touching
neural_processor_packed.v. Deliberate stop: closing the rest needs
that shared, load-bearing module touched -- a larger, more careful
step (verify against both N=2 and N=16) documented as next_action,
not attempted without further direction.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01MUG92aM9m68TRc4rG55BcC
sdram_arbiter_hier.v: fixes EXP-0093's own real, traced P&R timing
failure (flat 21-way req_wdata mux, route-delay-dominated). Reuses
sdram_arbiter_n.v unmodified, twice: 4 leaf instances (NUM_REQ=5, one
per group) + 1 top instance (NUM_REQ=5: 4 groups + host, host
bypassed/unpipelined), one real pipeline register stage between
levels. Isolated verification (tb_sdram_arbiter_hier.v): 23/23 PASS.
Two real bugs found and fixed via signal tracing: a testbench helper
not waiting for grant before firing req, and a genuine RTL lost-pulse
bug at the leaf-to-top boundary (a transient one-shot request could be
dropped if the top level was busy with a different group) -- fixed
with a sticky per-group pending_req_r latch.
Wired into n16_system_ddr3_top.v (drop-in). Real, full P&R re-run:
WNS improved -0.913ns -> -0.646ns, TNS -690ns -> -97.5ns, failing
endpoints 3021 -> 771 -- substantial, measured improvement, confirming
the arbiter was correctly root-caused (bottleneck moved elsewhere:
neural_processor_packed.v's own already-thin-margin MAC datapath,
eroded by N=16's higher overall congestion). Functional xsim still
32/32 PASS. Timing not yet fully closed -- real next steps documented,
not yet attempted without further direction.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01MUG92aM9m68TRc4rG55BcC
Real place_design/route_design against XC7A100T-CSG324-2: post-route
utilization holds (128 DSP48E1/53.33%, matching EXP-0091's projection),
but real timing fails on clk_pll_i (155.039MHz): WNS=-0.913ns,
WHS=+0.029ns, 3021 failing setup endpoints. Root-caused to
sdram_arbiter_n.v's req_wdata mux, now a real 20/21-way select (up
from 3-way at N=2) feeding mig_native_adapter.v's wdata_lat_reg.
N=16 is functionally correct (EXP-0092) but not yet timing-closed --
honestly not ready for real hardware at the target clock. N=2
(EXP-0088) remains the trustworthy, deployable signoff. Real options
for closing timing documented as next_action, not yet attempted.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01MUG92aM9m68TRc4rG55BcC
tb_n16_system_ddr3.v, adapted from tb_n2_system_ddr3.v's own real DDR3-
model methodology (real mig_7series_0_mig, real 2-chip ddr3_model.sv,
real Vivado xsim). Submits 32 positions across all 4 groups of
n16_system_ddr3_top.v's own real neural_director_grouped.v + 4x
systolic_group.v + 20-way arbiter. 32/32 PASS, 0 errors.
This confirms EXP-0091's synthesis-only result (0 errors, 128
DSP48E1/53.33%) reflected real functional correctness, not just
connectivity -- the grouped Director's octet dispatch, the new
arbiter's slot map, and the shared-weight-broadcast barrier all work
correctly wired together at full N=16 scale.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01MUG92aM9m68TRc4rG55BcC
Adds n16_system_ddr3_top.v, directly adapted from n2_system_ddr3_top.v's
own proven structure: same real MIG, spi_host_bridge_v3.v, flash_spi_
master.v, host_mem_bridge.v, all completely unmodified (confirms
EXP-0090's zero-protocol-change finding holds at full N=16 scale). The
real differences: neural_director_grouped.v replaces neural_director_
packed.v, 4x systolic_group.v replace 2x packed_slot.v, and the shared
arbiter grows to a real 21-way NUM_REQ (4 group weight-fetch + 16 PE
activation/writeback + 1 host_mem_bridge).
Real synthesis-only result: 0 Errors, 0 Critical Warnings, 128 DSP48E1
of 240 (53.33%) -- an exact real match to docs/ARCHITECTURE_ANALYSIS.md
S5.6's own original brainstorm DSP projection, now confirmed by real
synthesis instead of estimated.
Found and root-caused a real Vivado project quirk (not an RTL bug --
verified separately via a clean Icarus elaboration with stub modules
for mig_7series_0/STARTUPE2): a fresh add_files + update_compile_order
didn't make synth_design -top <newmodule> find the module. Fixed by
explicitly setting the fileset's own top property before synth_design.
CLAUDE.md updated with this as the real, confirmed procedure for adding
any future brand-new top-level module.
Honestly scoped: synthesis-only (connectivity/width correctness), NOT
yet a real functional xsim test and NOT yet real P&R timing -- both
real, disclosed next steps.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01MUG92aM9m68TRc4rG55BcC
Adds neural_director_grouped.v, a direct extension of neural_director_
packed.v's own already-proven 2-position pairing discipline to 8-position
octets (matching systolic_group.v's fixed 4 PEs x 2 lanes). Real,
deliberate finding: the host-facing SPI/WRITE_JOB submission protocol
needs zero changes -- the host just submits 8 jobs sharing a weight base
instead of 2, the same real pattern already required today.
Real out-of-context synthesis of one systolic_group.v: 32 DSP48E1
(13.3%), confirming the original brainstorm's own DSP projection exactly.
Found and fixed two real bugs: (1) a wraparound-arithmetic width bug in
the octet index computation (same class already flagged for address
math elsewhere in this project -- needs N+1 bits before the mod-reduce
compare, not N); (2) a real, generalizable testbench race -- driving
stimulus on the same clock edge the DUT samples on works fine with a
natural gap between pulses (every prior testbench in this project has
one) but silently double-registers data when called back-to-back with
zero gap, confirmed via real signal tracing. Fixed with @(negedge clk)
stimulus; CLAUDE.md's existing blocking/nonblocking testbench-race
lesson extended to cover this new trigger.
Verified via tb_neural_director_grouped.v: 4/4 PASS (octet dispatch +
per-PE addressing, stall-not-mis-dispatch on a mismatched octet, queue
wraparound).
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01MUG92aM9m68TRc4rG55BcC
Adds packed_pe.v (packed_slot.v's compute+activation-fetch+writeback
subsystem, reusing ddr_prefetch_mgr.v/neural_processor_packed.v/
result_writeback.v completely unmodified, with its own private
weight-fetch removed) and systolic_group.v (one real layer_prefetch_
ctrl.v+layer_weight_buffer.v+weight_tile_gather.v shared by 4x
packed_pe.v via a real, barrier-synchronized broadcast bus).
Real design choice confirmed with the user before writing any RTL
(AskUserQuestion, concrete topology preview): shared-weight broadcast,
not a literal PE-to-PE systolic shift register -- achieves the real,
quantified rationale (4x reduction in redundant weight-fetch DDR3
traffic per group of 4 PEs) with much lower real risk than genuine
inter-PE pipeline fill/drain.
The real new design is the barrier: each PE's own tcnt is the join key
against the group's broadcast tcnt, self-synchronizing regardless of
which PE is momentarily ahead/behind (e.g. a real DDR3 row-switch
stall on one PE's own activation fetch). Found and fixed a real bug
during verification (not by inspection): the first full test run
reported every result as undefined despite every control-flow signal
tracing correctly -- root-caused via real signal tracing down to a
5-way test arbiter bus mis-sliced at the wrong slot offset (single-bit
handshake buses happened to use a correct range and masked it from the
control-flow trace; only the wide, byte-offset buses were wrong).
Verified in isolation (tb_systolic_group.v, real Icarus xsim, real
sdram_arbiter_n.v generalized to NUM_REQ=5 with zero changes): 8/8
PASS across 2 consecutive group jobs (exercising the barrier's own
per-job reset path, not just cold start).
Deliberately scoped to the isolated mechanism only, per this project's
"one variable at a time" discipline -- Director/SPI job dispatch for
group jobs, a real N=16 top-level, and real P&R are real, disclosed
next steps, not done here.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01MUG92aM9m68TRc4rG55BcC
Real in-context P&R confirms the result-writeback engine (EXP-0088)
closes timing with essentially zero cost: WNS=+0.099962ns (vs
EXP-0086's +0.095707ns), WHS=+0.036275ns, 0 failing endpoints. 6642
LUTs (+260 for the new engine), 16 DSP48E1 unchanged. This is now the
current, trustworthy signoff, promoted over EXP-0086/0087's own
pointers in both docs.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01MUG92aM9m68TRc4rG55BcC
Adds result_writeback.v, one instance per packed_slot.v, writing each
completed job's result directly into DDR3 at the job's own
result_addr_a/b instead of driving literal top-level pins -- the same
architectural shape as the weight-fetch path, in reverse. job_done now
means "durably in DDR3", not "captured in a register only a pin could
see". n2_system_ddr3_top.v's own s0_result_data_a/b, s1_result_data_a/b
top-level package pins are removed (and the now-dangling XDC constraint
for them), closing the real, hard scaling blocker docs/ARCHITECTURE_
ANALYSIS.md flagged since EXP-0074/0079 (8 bits x 2 lanes x N cores ->
256 pins at N=16).
Addressing reuses the exact same JOB_ADDR_WIDTH->ctrl-bus-word
truncation x_base_a/w_base already use (verified against act_tile_
fetch.v's/layer_prefetch_ctrl.v's own real code, not guessed). The host
reads results back via the already-existing READ_MEM (0x02) SPI opcode
-- no new protocol. A real EXP-0066-class bug (issuing ctrl_req before
mem_grant) was caught and fixed before ever compiling, by re-deriving
the design against act_tile_fetch.v's own proven S_MEMWAIT/S_GAP
sequencing.
Verified two ways: tb_packed_slot.v extended with a real DDR3
read-after-write check (9/9 PASS, confirms the write actually landed,
not just that job_done pulsed); tb_n2_system_ddr3.v re-run via real
xsim to confirm correct behavior under real 2-slot shared-bus
arbitration (8/8 PASS, 0 errors, consistent timing with EXP-0087's own
baseline for this workload).
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01MUG92aM9m68TRc4rG55BcC
Re-measured ddr_prefetch_mgr.v's (EXP-0083) real benefit against the
now-closed 32-bit DDR3 channel (EXP-0086), per this project's own
standing plan. Real result: the 2.86% benefit measured at the old
16-bit channel is GONE at 32-bit (WITH: 100663.1335ns vs WITHOUT:
100656.6835ns -- a 0.0064% regression, statistically a wash). The
wider channel's lower per-tile latency already absorbs the gap the
look-ahead prefetch used to hide. Kept wired in for correctness/
timing-neutrality (real P&R already signs off with it included), but
it's no longer a real performance win. Updated docs/ARCHITECTURE_
ANALYSIS.md and docs/PHYSICAL_REALIZATION.md accordingly.
Found and fixed 3 real testbench/simulation-setup bugs along the way:
- tb_n2_system_ddr3.v and tb_mig_native_adapter.v still had a stale
CLKIN_PERIOD=2900 (the FAILED EXP-0084 clock period) instead of the
current real, closed 3225ps (EXP-0086).
- tb_n2_system_ddr3.v used SystemVerilog-only $signed(8'(...)) cast
syntax, invalid for xvlog's default plain-Verilog mode -- fixed via
an intermediate 8-bit reg.
- Building a fresh sim_1 fileset needs the real MIG simulation
dependency set added explicitly (mig_7series_0_mig.v is marked
USED_IN_SIMULATION=0 in the project since testbenches bypass the
public wrapper); verilog_define is a fileset-level property, not
per-file, in this Vivado version.
New measurement-only fork (not part of the real synthesis target, per
fork-before-promote discipline): packed_slot_noprefetch.v +
tb_n2_system_ddr3_noprefetch.v, reproducing the pre-EXP-0083 direct
per-tile activation-fetch sequencing for a fair A/B baseline.
Also adds docs/BOM.md and docs/PINOUT.md: a real component list (DDR3
x2, flash, FPGA already verified; clk_ref oscillator and an ESP32-S3-
WROOM-1 module newly verified in-stock on LCSC; sys_clk oscillator
flagged as needing a custom-programmed order, no off-the-shelf SKU at
the required 310.077MHz) and a consolidated, board-layout-ready pinout
extract of PHYSICAL_REALIZATION.md's own pin tables.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01MUG92aM9m68TRc4rG55BcC
Reverting Clock Period to 3225ps (keeping Data Width=32) closes real
timing: WNS=+0.095707ns, WHS=+0.036275ns, 0 failing endpoints, all
user-specified constraints met. This is the real final signoff for the
32-bit DDR3 channel widening effort (EXP-0083 through EXP-0086),
replacing EXP-0083's 16-bit-era baseline as the project's current
trustworthy number. Confirms the EXP-0084 root-cause analysis: the
earlier -0.618ns failure was caused by a separate, stacked clock
speedup, not the width change itself.
Also found and fixed a second, wholesale real occurrence of the
stale-import bug: the MIG wizard regeneration needed to revert Clock
Period silently re-imported the entire v3 RTL tree (9 files) plus the
top XDC back to pre-EXP-0084 stale copies, not just the file(s) the
regeneration touched. CLAUDE.md's lesson extended accordingly.
User-requested hardware notification so the ESP32 can be
interrupt-driven instead of polling STATUS in a loop.
spi_host_bridge_v3.v: new job_out_done input (wired from
neural_director_packed.v, already available at the top level) and new
data_ready_n output. A sticky irq_pending register sets on job_out_done
(latched, survives the pulse itself deasserting) and clears when the
host completes a real STATUS (0x20) or REG_READ(0x02) transaction -
reusing cs_rose, the same real transaction-complete event the module
already relies on elsewhere, not a new mechanism. dir_error is ORed in
live/combinational, not latched. SET has priority over CLEAR on the
rare cycle both coincide.
Real pin: D14, bank 15 (already 3.3V, alongside the SPI bus and
sys_rst) - tentative, not yet a final board decision. Deliberately
added after EXP-0084's own P&R iterations settled, so it didn't
complicate that already-tight I/O/VCCO budget mid-fix. Its own real
P&R verification is deferred to the next real P&R run (already needed
to close EXP-0084's clock-period timing gap), not run separately
against a config already known to fail timing for unrelated reasons.
Real verification: tb_spi_host_bridge_v3.v extended with 10 new checks
(idle state, sticky set, mid-transaction hold, real-acknowledge clear,
unrelated-register non-acknowledge, dir_error live assert/clear).
49/49 PASS.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01MUG92aM9m68TRc4rG55BcC
Real 32-bit DDR3 widening (2x MT41J128M16JT-125:K chips ganged in
parallel, user's own MIG wizard session). Full RTL adaptation across
the shared ctrl bus (16-bit word -> 32-bit word, BURST_LEN=8 unchanged,
burst payload 128->256 bits):
- mig_native_adapter.v: app_wdf_data/app_rd_data 64->128 bits (real,
confirmed against the regenerated MIG wrapper), beat count unchanged.
- act_tile_fetch.v: real logic change - burst now holds 4 tiles instead
of 2 (sel_lat extended to 2 registered bits, 4-way case mux instead
of 2-way ternary, same request-time-registered-select discipline as
EXP-0081). Not a further bytes/MAC reduction, just what's needed to
keep 100% packing utilization at the larger burst.
- host_mem_bridge.v: real addressing redesign - host-facing 16-bit-word
contract kept unchanged (ESP32 firmware unaffected), internally
translated onto the new 32-bit-native ctrl bus.
- sdram_arbiter_n.v, layer_prefetch_ctrl.v, packed_slot.v,
ddr_prefetch_mgr.v, n2_system_ddr3_top.v: mechanical width bump plus
doubled ddr3_dq/dqs/dm pins and the real differential sys_clk/clk_ref
top-level ports the regenerated MIG now requires.
New burst_mem_model32.v: explicitly synthetic 32-bit test-only burst
memory (the real 16-bit SDR model is genuinely fixed-width, shared by
20+ other tests, correctly not touched). Found and fixed a real
address-aliasing bug in it during bring-up (MEM_ADDR_BITS=16 silently
wrapped a real 0x10000 test address to 0).
Real verification: all isolated testbenches re-verified (10/10, 33/33,
32/32, 7/7, 9/9 PASS), plus real xsim against the real 2-chip DDR3
model (tb_mig_native_adapter.v 12/12 PASS, tb_n2_system_ddr3.v 8/8
PASS, both chips visibly returning different real data).
Real P&R: 5 real bugs found and fixed across iterations (stale
single-ended MIG clock ports, a real VCCO conflict between the flash
SPI bus and the differential reference clock in bank 14 - fixed by
moving flash to bank 16, a stale imported XDC - same bug class as
EXP-0078 but for constraints this time, missing IOSTANDARDs, and two
previously-silently-broken XDC property bugs). Route completes 100%,
but real timing does NOT close: WNS -0.618ns, 213 failing endpoints.
Honest root cause: the violation is inside neural_processor_packed.v's
own packed-MAC accumulation tree, unchanged since EXP-0059 - it has
real margin at the old 155.039MHz ui_clk but not at the new 172.414MHz
the paired clock-period change produced. This is NOT caused by the
32-bit width change itself. Width alone, even at the old clock, already
delivers the full intended 2x bandwidth gain (1.24 -> ~2.48 GB/s) -
width and clock rate are separable levers. Current trustworthy timing
signoff remains EXP-0083 (16-bit, +0.073ns) until the clock period is
reverted toward 3225ps (keeping Data Width=32) in one more real,
user-gated MIG wizard session.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01MUG92aM9m68TRc4rG55BcC
S5.6.1: opportunistic BRAM cache for activation tiles - exploits real,
currently 0%-utilized Block RAM to catch whatever locality the workload
happens to have, without committing to a specific reuse pattern the way
the systolic direction does. No cache-invalidation problem given the
current write-once-before-job protocol.
S5.6.2: host-side (ESP32) job-queue reordering - a software-only
"DDRManager" upstream of ddr_prefetch_mgr.v, grouping jobs with nearby
DDR3 addresses before submission to reduce row-switch cost with zero
RTL and zero timing-margin risk. Both marked exploratory, not decided,
not built - same as S5.6's systolic direction.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01MUG92aM9m68TRc4rG55BcC
Brainstorming session outcome: instead of flat N=16 independent DDR3
requesters, group cores into 4 weight-stationary systolic chains of 4
PEs each - reduces independent DDR3 contenders from 16 to 4 while
preserving task-level parallelism across the 4 groups. Captured as
docs/ARCHITECTURE_ANALYSIS.md S5.6, explicitly marked exploratory/not
decided/not built - revisit after the 32-bit channel widening and real
N=2/4/8 flat-core scaling tests produce real numbers.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01MUG92aM9m68TRc4rG55BcC
New ddr_prefetch_mgr.v wraps act_tile_fetch.v with a depth-2 ping-pong
buffer, issuing the next tile's DDR3 fetch as soon as the fetch engine
is free instead of waiting for packed_slot.v to finish consuming the
current tile. Wired into packed_slot.v's tile loop (job-level start
instead of per-tile req), simplifying the S_TILEWAIT join in the process
(ddrpf_tile_valid is level-held, no separate act_seen latch needed).
Verification: new tb_ddr_prefetch_mgr.v (25/25 PASS after fixing a real
testbench polling race found via iteration-tagged tracing, not an RTL
bug), tb_packed_slot.v re-run unmodified (9/9 PASS, bit-identical
results), tb_n2_system_ddr3.v re-run via real xsim against real
ddr3_model.sv (8/8 PASS). Real P&R: WNS +0.073ns (up from EXP-0082's
+0.068ns), LUTs 5644, DSP48E1 16 unchanged, 0 failing endpoints.
Honest result: real A/B on the actual DDR3 backend (same testbench,
before/after) shows a real but modest 2.86% reduction in total
simulated time - smaller than the original hypothesis suggested, because
neural_processor_packed.v already accepts one operand per cycle, so the
per-tile dead time being removed was already small relative to real DDR3
fetch latency. Docs updated to report this honestly rather than oversell
it; the larger multi-slot DDRManager is deferred pending re-measurement
against the (still pending, user-gated) 32-bit channel widening.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01MUG92aM9m68TRc4rG55BcC
- PHYSICAL_REALIZATION.md: replace stale "1 tile = 1 burst" layout
description with the real EXP-0081/0082 "2 tiles = 1 burst" convention;
add EXP-0082 signoff row and history table.
- ARCHITECTURE_ANALYSIS.md: mark §5.1 (denser activation packing) DONE with
real re-measured numbers (bandwidth ceiling fraction 25%->50%, WNS
+0.030->+0.068ns); add §5.4, the real device-data-backed comparison of
32-bit single-channel widening vs a second independent DDR3 channel
(decided: 32-bit widening, per real DQS/bank pin-conflict analysis);
update scaling-path recommendation to reflect the user's final directive
(widen channel -> build DDRManager -> N=2/4/8/16 tests, N=8 target, N=16
documentary).
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01MUG92aM9m68TRc4rG55BcC
Real P&R: WNS +0.068ns (up from +0.030ns), 0 failing endpoints, 5437
LUTs, 16 DSP48E1. Confirms EXP-0081's "register the select bit at
request time" design genuinely kept the fix off the critical path.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01MUG92aM9m68TRc4rG55BcC
Implements the highest-leverage fix from EXP-0080's bottleneck
analysis: act_tile_fetch.v now packs 2 consecutive tiles per DDR3
burst (even tile low 64 bits, odd tile high 64 bits) instead of 1
tile per burst, halving real DDR3 bytes-per-useful-byte. Timing-safe
by construction: the tile-index select bit is registered at request
time, long before the real DDR3 round-trip completes, never racing
the arriving read data (unlike the runtime part-select pattern
EXP-0079 deliberately avoided).
Re-verified at all 3 levels (isolated engine 8/8, packed_slot.v 9/9
with bit-identical results to EXP-0079, full N=2 system on real DDR3
8/8) -- the real JEDEC trace now shows no half-burst padding, direct
confirmation the fix works in practice, not just in theory.
Also: real device data gathered on this package's I/O bank layout
(only 5 banks total, 14/15/16/34/35) informing the next bandwidth step
(32-bit-wide single controller recommended over a second independent
channel, given the pin/logic cost comparison).
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01MUG92aM9m68TRc4rG55BcC
Before building N=4/8/16 core scaling, did the requested full
analysis. Real finding: using measured DDR3 throughput (1.24 GB/s,
from the actual EXP-0079 JEDEC trace) against calculated compute-side
need (4.96 GB/s for one core at peak DSP throughput, given the
current activation memory layout's 2x byte overhead), the system is
memory-bandwidth-bound already at N=1/N=2, not DSP-bound (only 6.67%
DSP used). Scaling core count today would show no real throughput
gain.
docs/ARCHITECTURE_ANALYSIS.md: full module review + ranked
interventions -- result-writeback engine (blocker), denser activation
packing (highest-leverage bandwidth fix), then the user's own proposed
DDRManager/orchestrator-prefetch idea (design-sketched, grounded in
neural_director_packed.v's existing job queue, explicitly scoped as
complementary to denser packing, not a substitute for it), THEN
N-scaling with real per-N P&R signoff.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01MUG92aM9m68TRc4rG55BcC
Closes the last major disclosed functional gap: packed_slot.v's
activation data was read through a combinational stand-in since
EXP-0062. New act_tile_fetch.v reads activation tiles directly from
DDR3 (no on-chip buffering needed, unlike weights -- activation data
has no reuse), sharing each slot's existing ctrl port with its own
weight-prefetch engine. Real memory layout: one full BURST_LEN=8-word
burst per tile, deliberately avoiding any runtime-indexed part-select
given this project's thin P&R timing margin (EXP-0078).
Verified at three levels: act_tile_fetch.v alone (6/6), packed_slot.v
with real preloaded activation data (9/9), and the full N=2 system
against real DDR3 via xsim (8/8, 0 errors) -- the first time this
project's compute path has been verified end-to-end with real DDR3
for both weights and activations.
Retired hardware/v3/rtl/n2_system_top.v and its testbench (pre-DDR3
SDR-placeholder era, fully superseded by n2_system_ddr3_top.v).
Also: docs/PHYSICAL_REALIZATION.md (real pinout/parts/timing/protocol
reference for the physical board) and CLAUDE.md (persistent project
instructions for future Claude Code sessions).
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01MUG92aM9m68TRc4rG55BcC
Found and fixed a real Vivado project-management bug: two source
files (n2_system_ddr3_top.v, spi_host_bridge_v3.v) had stale imported
copies (plus a duplicate at a second path) that silently kept being
used in synth+impl despite live edits, making the first "flash bridge
included" P&R run silently synthesize the OLD design (STARTUPE2
Used=0/1 gave it away). Fixed by removing the stale/duplicate entries
and re-adding both files as direct (non-copied) references.
Final real P&R: STARTUPE2 Used=1/1 (confirms the flash bridge is
genuinely placed/routed), timing still closes but margin is now
thinner and real: WNS +0.013ns, WHS +0.032ns, 0 failing endpoints.
5213 LUTs, 16 DSP48E1.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01MUG92aM9m68TRc4rG55BcC
Implements the user's board architecture: config flash wired
exclusively to the FPGA, host (ESP32) reaches it only through the
FPGA. flash_spi_master.v is a plain byte-wide SPI master using
STARTUPE2 to reclaim CCLK after configuration (the real, Xilinx-
documented "indirect SPI flash programming" technique, UG470 p94-96).
New opcode 0x40 FLASH_XFER in spi_host_bridge_v3.v relays bytes
byte-for-byte between host and the physical flash bus -- the host
decides the exact SPI NOR command sequence (verified against the real
W25Q32JV datasheet), this RTL knows nothing about flash semantics.
Found and fixed two real bugs during verification: a byte-assembly
off-by-one in flash_spi_master.v, and a genuine protocol-latency bug
in the FLASH_XFER opcode's response timing (needed 2 trailing margin
bytes, not 1 -- the internal flash transfer doesn't start until the
triggering byte finishes, so 1 byte of margin isn't enough). 39/39
tests pass end to end (host SPI -> bridge -> flash_spi_master ->
behavioral flash model).
Wired into n2_system_ddr3_top.v with real pin constraints (flash_mosi
=K17/flash_miso=K18/flash_cs_n=L13, the same pins reserved-but-unused
in EXP-0075) and BITSTREAM.CONFIG.PERSIST=FALSE made explicit.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01MUG92aM9m68TRc4rG55BcC
Found a real, previously-masked bug in spi_host_bridge_v3.v's physical
layer (inherited unchanged from V1/V2): the bit_count==0 MISO bypass
corrupts the last bit of any multi-byte response whose value happens
to end in a 1 -- every prior test's response data coincidentally
ended in 0, hiding it until the new DEVICE_ID register (0x...01)
exposed it via a real bit-exact mismatch. Fixed by removing the
bypass (verified unnecessary for this protocol's actual usage).
Added REG_WRITE/REG_READ opcodes (0x30/0x31) and a register file
(DEVICE_ID/CONTROL/STATUS/N_SLOTS) for general device control beyond
job submission, per explicit user request. Full regression: 38/38
PASS, including new cases specifically targeting the bit-corruption
bug for both REG_READ and READ_MEM.
New hardware/v3/constraints/n2_system_ddr3_top.xdc: reserves the
FPGA's dedicated Master-SPI config-flash pins (found colliding with
auto-placed design ports in the real routed checkpoint) and assigns
the neural-processor management SPI to real, verified-free, edge-
adjacent pins on xc7a100tcsg324-2.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01MUG92aM9m68TRc4rG55BcC
n2_system_ddr3_top.v: the first synthesizable top wiring the real
mig_7series_0 DDR3 controller (public wrapper, real calibration) +
mig_native_adapter.v + sdram_arbiter_n.v (3-way: 2 packed_slot + host
raw-access) + neural_director_packed.v + spi_host_bridge_v3.v.
Real Vivado in-context synth+impl against the actual MIG-generated
XDC (pin locations, DDR3 timing exceptions) on xc7a100tcsg324-2:
route_design 100%, all timing constraints met (WNS +0.040ns, WHS
+0.048ns, 0 failing endpoints), 310.078MHz DDR3 PHY clock / 155.039MHz
compute domain, 5140 LUTs / 5952 regs / 16 DSP48E1 / 0 BRAM.
Fixed three real issues found getting here: a SystemVerilog literal
synth_design can't parse, MIG stub port mismatch (calib_tap_* isn't
exposed in this IP config), and a genuine design mistake -- exposing
packed_slot.v's activation-fetch stand-in ports as literal top-level
pins demanded ~360 I/O against the package's 324 total. Made that
interface internal (stub-driven) instead.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01MUG92aM9m68TRc4rG55BcC
Replaced three uses of the SystemVerilog '0 self-sizing literal with
explicit-width zero-fill so the file synthesizes under Vivado's
synth_design (which has no -sv equivalent in this flow), needed while
adding this module to the real in-context P&R project.
Re-running its isolated regression after that edit surfaced 3/8
failures. Root-caused via git stash (reproduces on the untouched
committed file, not caused by this edit) and a DUT-internal $display:
tb_neural_director_packed.v's own submit_job task drove DUT inputs
with blocking assignment across two separate @(posedge clk) waits,
racing the DUT's own always block under Icarus and causing a spurious
duplicate enqueue. Fixed by switching to nonblocking assignment
(race-free by construction). neural_director_packed.v itself was
correct all along - 8/8 tests pass after the testbench fix.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01MUG92aM9m68TRc4rG55BcC
Forked from V2's spi_host_bridge.v after finding two real protocol
mismatches: WRITE_JOB carried dependency-manager fields (required/
producer_ids) that neural_director_packed.v's job_in_* port doesn't
have (no dependency manager exists in V3 -- dropped, disclosed, not
silently ignored), and WRITE_MEM/READ_MEM assumed a word-granularity
host-arb port V3 never had (now wired through host_mem_bridge.v,
EXP-0071). Physical SPI layer carried over unchanged.
Verified standalone: 18/18 tests, 0 errors, including a case
exercising the narrower 25-bit MEM_ADDR_WIDTH's own top bit.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01MUG92aM9m68TRc4rG55BcC
Closes part of the gap found re-auditing spi_host_bridge.v against V3:
V3 had no host raw-memory-access path into DDR3 at all. This module
translates single-16-bit-word req/wr/addr/wdata/lb_n/ub_n transactions
(spi_host_bridge.v's own WRITE_MEM/READ_MEM shape) into BURST_LEN=8
transactions on the shared arbiter, using the project's existing
DQM-style partial-burst masking technique.
Verified standalone against the SDR SDRAM placeholder: 16/16 tests,
0 errors, including cross-word-corruption checks on every burst
offset. Not yet wired into the N=2 system or driven by real SPI
opcode decode.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01MUG92aM9m68TRc4rG55BcC
Swapped mig_native_adapter.v + sdram_arbiter_n.v into the full N=2
system (neural_director_packed.v + 2x packed_slot.v), replacing the
SDR SDRAM placeholder used since EXP-0057. Verified against the real
Vivado-generated ddr3_model.sv end-to-end: 8/8 positions bit-exact
against golden model, 0 errors, real JEDEC command traffic observed.
This is the first fully real V3 system-level correctness result:
real packed DSP cores + real weight-reuse scheduling + real N-way
arbitration + real DDR3 timing, all verified together.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01MUG92aM9m68TRc4rG55BcC
TEST2 fired all 3 simulated requesters' one-shot req pulse
unconditionally, not waiting for each one's own grant -- an
unrealistic stimulus that doesn't match packed_slot.v's real
S_MEMWAIT usage (wait for grant, then fire). Rewrote with parallel
fork branches, each waiting for its own req_grant first, still
exercising the real simultaneous-activation contention case.
7/7 PASS, 0 errors. sdram_arbiter_n.v is now genuinely verified, not
just written.
Full writeup in hardware/v2/logs/experiments.log EXP-0069.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01MUG92aM9m68TRc4rG55BcC
New hardware/v3/rtl/mig_native_adapter.v: adapts this project's
established req/wr/addr/wdata/wmask->rdata/ready/busy contract to the
real MIG 7-series native app interface (app_addr/app_cmd/app_en,
app_wdf_data/app_wdf_mask/app_wdf_wren/app_wdf_end, app_rd_data/
app_rd_data_valid/app_rd_data_end), derived from this project's own
real generated mig_7series_0.v port widths, not assumed. Runs in the
ui_clk domain (MIG's own generated clock becomes this project's
system clock going forward).
Verified against MIG's own real, vendor-shipped DDR3 behavioral model
(ddr3_model.sv) via real Xilinx xsim/xvlog/xelab (UNISIM primitives
in MIG's PHY require this over Verilator): 12/12 write-then-read-back
transactions bit-exact, 0 errors, real JEDEC command sequence observed
(Activate/Write/Read/Precharge). Confirms the app_cmd encoding and
burst/beat sequencing on first real test.
Also adds hardware/v3/rtl/sdram_arbiter_n.v (generalized N-way
arbiter, generalizing EXP-0066's 2-way version for N>2 scaling and a
future host-access requester) -- its own isolated test currently
HANGS, root cause not yet found, do not trust this module yet
(disclosed, not hidden).
Full writeup in hardware/v2/logs/experiments.log EXP-0068.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01MUG92aM9m68TRc4rG55BcC
New hardware/v3/rtl/n2_system_top.v: synthesis wrapper around the
EXP-0066-verified system (neural_director_packed.v + arbiter + real
SDRAM controller + 2 real packed_slot.v instances).
Real Vivado post-route: 16/240 DSP48E1, WNS -2.570ns @ 200MHz ->
Fmax ~132.1MHz -- only -2.1% vs the isolated single core (134.9MHz,
EXP-0059). Unlike V2/ECP5 (where the real full-system Fmax was
measurably lower than the isolated-core number), this Director+
arbiter architecture shows no comparable penalty at N=2, real
confirmation (not projection) that the earlier ~55-85x-over-ESP32-S3
estimate's key assumption holds at this scale.
Full writeup in hardware/v2/logs/experiments.log EXP-0067.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01MUG92aM9m68TRc4rG55BcC
New sdram_slot_arbiter2.v + tb_np_director_n2_system.v: real
neural_director_packed.v dispatching to 2 real packed_slot.v
instances sharing one real SDRAM controller. Jobs submitted one at a
time through the Director's own producer interface -- the Director's
own scheduling decisions determine slot assignment here, unlike every
prior V3 test.
Bug 1 (real, structural): the arbiter's first design registered its
grant one cycle late; layer_prefetch_ctrl.v's ctrl_req is a one-shot
pulse with no retry (every prior use wired it directly to a
controller, never behind arbitration), so a slot's first request
could be silently lost, hanging it forever. Fixed with a new
S_MEMWAIT state in packed_slot.v (wait for a combinational mem_grant
before ever pulsing layer_prefetch_ctrl's start) and a combinational-
first grant in the arbiter.
Bug 2 (testbench): node_id used a stray bit-slice (li[15:8]) instead
of a real multiply, making every layer produce the same node_ids and
silently checking results against the wrong layer's golden value.
Fixed.
Result: 12/12 PASS, 0 errors, real concurrent execution across both
slots (slot 0: positions {0,1,4,5,8,9}, slot 1: {2,3,6,7,10,11}).
Also noted (user correction): the SDR SDRAM controller used
throughout this memory path is a declared placeholder -- the real
target is DDR3 on a custom XC7A100T board, not yet built.
Full writeup in hardware/v2/logs/experiments.log EXP-0066.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01MUG92aM9m68TRc4rG55BcC
Promotes EXP-0062's own procedural testbench sequence (prefetch ->
buffer swap -> per-tile gather -> operand streaming -> result
capture) into real synthesizable RTL, wrapping layer_prefetch_ctrl.v
-> layer_weight_buffer.v -> weight_tile_gather.v ->
neural_processor_packed.v behind a 9-state FSM matching
neural_director_packed.v's own per-slot contract.
First run: 4/9 failed, deterministic. Root-caused (not a sequencer
bug): the testbench's own w_base computation wrongly treated it as a
byte address needing *2 conversion; layer_prefetch_ctrl.v expects a
word address directly, and packed_slot.v already passes it through
unconverted to match. Fixed the testbench.
Re-verified: 9/9 PASS, 0 errors, bit-exact results and correct
node_id/result_addr passthrough, entirely self-sequenced (no
testbench-side procedural driving of the sub-modules).
Full writeup in hardware/v2/logs/experiments.log EXP-0065.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01MUG92aM9m68TRc4rG55BcC
Forked from neural_director.v (M5): dispatches PAIRS of queued jobs
(sharing w_base+n_tiles) to packed-core slots instead of one job per
slot, matching neural_processor_packed.v's A/B job structure. If the
two oldest queue entries don't share w_base/n_tiles, the Director
stalls (never mis-pairs) -- a disclosed scope limitation, not hidden.
Isolated testbench with behavioral per-slot stubs (same DEC-0007 scope
decision as tb_neural_director.v). First run: 3/7 tests failed --
investigated each, root-caused as testbench timing bugs (checking
dispatch state before the Director's own FSM had caught up, and a
held-too-long job_in_valid making push counts ambiguous), not Director
bugs. Fixed the testbench, re-verified: 8/8 PASS, 0 errors.
Full writeup in hardware/v2/logs/experiments.log EXP-0064.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01MUG92aM9m68TRc4rG55BcC
New hardware/v3/rtl/np_packed_weight_reuse_top.v: flat structural
synthesis wrapper around the EXP-0062-verified module chain (real SDR
SDRAM controller -> layer_prefetch_ctrl.v -> layer_weight_buffer.v ->
weight_tile_gather.v -> neural_processor_packed.v).
Real Vivado post-route: 8/240 DSP48E1 (unchanged, memory path uses
zero DSPs), WNS -2.502ns @ 200MHz -> Fmax ~133.3MHz, only -1.2% vs
the isolated single core (134.9MHz, EXP-0059). Real memory-path
control logic adds negligible Fmax cost at this scale.
Full writeup in hardware/v2/logs/experiments.log EXP-0063.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01MUG92aM9m68TRc4rG55BcC
New hardware/v3/sim/tb_np_packed_layer_reuse.v: real SDR SDRAM ->
layer_prefetch_ctrl.v -> layer_weight_buffer.v -> weight_tile_gather.v
-> neural_processor_packed.v, ALL real synthesizable RTL (unlike
EXP-0058, which still had a testbench-only gather step).
First run: 15/16 PASS, 1 FAIL. Root-caused (not re-run away): a
testbench handshake bug, not a DUT bug -- operand_valid was held one
extra clock edge after each accepted tile, double-consuming stale
data every tile on every pair. 15 of 16 "passed" only because this
test's saturating outputs happened to clamp to the same value whether
or not the accumulator was inflated -- disclosed as a real methodology
risk, not swept under the rug. Fixed by dropping operand_valid the
same delta the handshake is observed.
Re-verified after the fix: 16/16 PASS, 0 errors, bit-exact against an
independent golden model, through the complete real RTL path.
Full writeup in hardware/v2/logs/experiments.log EXP-0062.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01MUG92aM9m68TRc4rG55BcC
Closes the gap EXP-0058 left testbench-only: assembling P_IN
sequential layer_weight_buffer.v byte reads into one weight_data
tile bus, as real RTL instead of a testbench driver task. Avoids the
runtime-indexed-part-select anti-pattern already found and fixed once
in neural_director.v (ERR-0027-class Fmax collapse) by using a fixed
shift-concat instead.
Verified in isolation against a real, unmodified layer_weight_buffer.v:
37/37 tests, 0 errors, bit-exact across sequential, back-to-back, and
non-sequential/repeated (real reuse-position-style) access patterns.
Full writeup in hardware/v2/logs/experiments.log EXP-0061.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01MUG92aM9m68TRc4rG55BcC
New hardware/v3/rtl/np_packed_array.v: flat array of 8 unmodified
neural_processor_packed.v instances, fully independent I/O, zero
shared arbiter/Director logic -- isolates exactly one variable
(DSP/placement density) from EXP-0059's single-core baseline.
Real Vivado post-route: 64/240 DSP48E1 (26.67%), WNS -2.592ns @
200MHz -> Fmax ~131.7MHz, only -2.4% vs the single-core 134.9MHz.
Placement density alone is NOT the main driver of the ECP5-era gap
between isolated-core and full-system Fmax -- narrows the question
for the still-unbuilt real Director/arbiter/memory integration.
Full writeup in hardware/v2/logs/experiments.log EXP-0060.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01MUG92aM9m68TRc4rG55BcC
Real Vivado 2026.1 run (not estimated) confirms the DSP48 packing
survives actual Xilinx synthesis: mac2_dsp_packed.v uses exactly 1
DSP48E1, and the full neural_processor_packed.v pipeline uses 8
DSP48E1/240 for 2 jobs -- half the DSP of two separate V2 cores for
the same work.
Post-route (real place_design+route_design, not synthesis-only):
WNS -2.414ns @ 200MHz -> Fmax ~134.9MHz, within 0.5% of the
post-synthesis-only estimate. This is the isolated compute core,
out-of-context -- not yet a real N-core system number, flagged as
such in the log entry.
Full writeup, including the two real toolchain fixes needed to get
Vivado running on this machine (CRLF line endings in installLibs.sh,
missing libncurses.so.5 on Ubuntu 26.04), in
hardware/v2/logs/experiments.log EXP-0059.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01MUG92aM9m68TRc4rG55BcC
New hardware/v3/ (Artix-7 port, branch v3-artix7): the compute engine
that makes the 100x-vs-ESP32 target theoretically reachable on
XC7A100T's 240 DSP48E1 budget.
mac2_dsp_packed.v: packs 2 INT8 MACs sharing one resident weight into
a single DSP48-shaped 25x18 multiply, exploiting this project's own
weight-stationary reuse pattern (layer_weight_buffer.v, EXP-0057/0058)
where one weight is genuinely multiplied against many different
activations. Verified exhaustively: 16,777,216/16,777,216
(weight,x0,x1) combinations, 0 errors.
Two real bugs found and fixed during that verification (both purely
arithmetic/RTL, not toolchain-related):
1. An off-by-one in a declared wire width caused Verilog's part-select
unsigned-by-default rule to corrupt sign extension on the upper
product field -- ~50% of vectors failed.
2. After fixing (1), still ~50% failed: concatenating two independently
sign-extended fields ({sext(x1,9), sext(x0,16)}) is NOT equivalent
to the real arithmetic sum x1*2^16+x0 whenever the lower field is
negative (its own two's-complement encoding "bleeds" an extra 2^16
into the concatenated value). Fixed by building the packed operand
with an explicit arithmetic shift-and-add instead of concatenation.
neural_processor_packed.v: full port of hardware/v2/rtl/
neural_processor.v's pipeline (same stage count/structure), doubled on
the accumulator/bias/activation/saturation side to process two
weight-reuse positions per weight-tile stream. Verified against TWO
real hardware/v2/rtl/neural_processor.v instances (job A / job B, same
shared weight, independent activations) -- 18/18 PASS, 0 errors,
covering the functional sweep, INT8 extremes, and back-to-back jobs.
A third real bug found in the process (in the new testbench, not the
RTL): clearing operand_valid/tile_last in the same simulation delta as
the handshake edge that should register tile_last=1 races against the
DUTs' own FSM evaluation of that same edge -- the same pulse-clearing
race class found three times already today in hardware/v2/sim (EXP-0058
and its follow-up commits). Fixed the same way: hold the pulse past the
edge with a real time delay (#1) before clearing.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01MUG92aM9m68TRc4rG55BcC
Real nextpnr-ecp5 resource data shows the ECP5 family (45F: 72
MULT18X18D, 85F: 156) cannot reach the 20x-1000x speedup targets
discussed today with this or any redesigned architecture -- N=16 was
already near the 85F's absolute physical ceiling of 19 cores. User
made an informed decision to pause the project rather than chase a
target this hardware family cannot physically deliver.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01MUG92aM9m68TRc4rG55BcC
Same class of testbench-vs-DUT scheduling race documented in EXP-0058
(tb_layer_prefetch_ctrl.v, tb_neural_processor_layer_reuse.v) was also
present here on ctrl_req/fill_done/consume_done: clearing a one-cycle
pulse on the very next @(posedge clk) let the clear land in the same
active-region pass as the edge the DUT needed to sample it at, so the
pulse could be silently missed. Confirmed via direct state tracing:
sdram_controller_openrow.v sat in S_IDLE with busy=0 forever after the
first burst, never latching req_pending for the second -- this is why
the file hung indefinitely rather than completing. Fixed with the same
#1-before-clear hardening as the other files.
Honesty note: fixing this hang exposed a SECOND, still-unfixed bug in
prefetch_layer's own fill_addr sequencing (real data-correctness
failures once the run actually completes, not just a hang) -- so
EXP-0057's own headline "7.16x real measured speedup" number is NOT
re-verified by this commit and should not be treated as confirmed. Not
pursued further -- see decisions.log for why (project paused).
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01MUG92aM9m68TRc4rG55BcC
New tb_neural_processor_layer_reuse.v wires the real SDRAM controller,
layer_prefetch_ctrl.v and layer_weight_buffer.v into a real
neural_processor.v compute engine: one resident filter is fetched once
and reused across 8 independent jobs per layer, verified bit-exact
against an independent golden dot-product model (32/32 PASS).
Also found and fixed a real testbench-vs-DUT scheduling race present in
tb_layer_prefetch_ctrl.v (and hardened in the new file): clearing a
one-cycle control pulse on the very next clock edge lands the clear in
the same active-region pass as the edge a receiving module's own
synchronous logic reads it at, so the pulse can be silently missed
depending on implementation-defined process ordering. This had been
silently preventing tb_layer_prefetch_ctrl.v's own claimed 8192/8192
result from ever actually being observed; fixed by holding the pulse
past the edge with a real time delay before clearing, and the
8192/8192 result is now genuinely reproducible (5/5 consecutive runs).
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01MUG92aM9m68TRc4rG55BcC
Per explicit instruction: when a bug/fix found in an experimental fork
also applies to the production file it was forked from, apply it
there too, not just in the fork.
dependency_manager.v: swaps in priority_encoder_lsb.v for the
first_ready_idx scan (was: serial O(N_NODES) for-loop). Bit-exact
equivalent, correctness-neutral by construction.
nms_activation_fill_ctrl_v3.v: adds the missing N_SLOTS==16 balanced
max-tree case (was: silently falling back to the slow flat scan for
any N_SLOTS not in {1,2,4,8}) -- this was the real cause of N_SLOTS=16
failing timing closure (23-24MHz vs 64MHz target), fixed to 71.01MHz
PASS in the experimental fork.
Verified on the REAL, unmodified production top (fpga_neural_v2_top.v,
N_SLOTS=4 default): tb_dependency_manager.v 4/4 PASS, board smoke test
11/11 PASS, D-Stress N=4 total_cycles=49927 (bit-exact, IDENTICAL to
the pre-fix baseline -- zero functional regression, as expected from a
pure combinational-depth change). Real nextpnr-ecp5 P&R (LFE5U-45F,
seed 1): 97.36MHz, PASS at 64MHz -- BETTER margin than the pre-fix
baseline's own 76.80-88.25MHz seed range, not just neutral.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01MUG92aM9m68TRc4rG55BcC
Built the real FSM version of EXP-0057's own task-based prefetch
pattern (bulk-sequential layer fetch via sdram_controller_openrow.v
into layer_weight_buffer.v), so it's an actual instantiable module,
not just a simulation convenience.
Found and fixed a real bug in the process: cur_fill_addr's own address
arithmetic bit-sliced BYTES_PER_BURST down to too few bits
(BYTES_PER_BURST[BIDXW-1:0]), silently truncating 16 to 0 -- every
burst's bytes landed at fill offset 0-15 instead of their real
position, overwriting each other (only each layer's last burst
survived). Root cause: misapplied a widening idiom used safely
elsewhere in this codebase to a case where the target width was
actually too small. Found via a standalone control-flow debug test
first, then tracing data once control-flow was cleared.
Verified: 8192/8192 bit-exact, 0 errors (was 512/8192 before the fix)
through the real controller + SDRAM model, 16 layers.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01MUG92aM9m68TRc4rG55BcC
EXP-0056: N_SLOTS=16 failed timing on LFE5U-85F (23-24MHz vs 64MHz
target). First hypothesis (dependency_manager.v's serial ready-scan)
was wrong but real -- built and verified priority_encoder_lsb.v (a
generic recursive tree encoder) and dependency_manager_fast.v, bit-
exact equivalent to the original, but integrated it made no real
difference (24.26MHz). The real cause, found from nextpnr's own
critical-path report: nms_activation_fill_ctrl_v3.v's balanced max-
tree was only ever extended to N_SLOTS in {1,2,4,8}, silently falling
back to the original slow scan for 16. Added the missing case
(nms_activation_fill_ctrl_v3_n16.v), verified isolated (10017/10017)
and functionally (D-Stress N=16 still 256/256 bit-exact). Real result:
71.01MHz, PASS at 64MHz (single seed so far).
EXP-0057: built layer_weight_buffer.v, a double-buffered per-layer
weight scratchpad (fill one buffer in the background from SDRAM while
compute reads many times from the other -- weight-stationary reuse,
as opposed to D-Stress's own deliberately zero-reuse pattern). Wired
to the real sdram_controller_openrow.v + sdram_model.v, no new
hardware. For the same 32768 bytes of useful data: zero-reuse costs
27048 real cycles, reuse costs 3777 -- 7.16x real measured speedup on
the SAME SDR SDRAM, no DDR3, no clock change. This is the answer to
whether DDR3 is necessary for a workload class that actually has
reuse (e.g. conv-style face recognition, unlike D-Stress) -- it isn't,
at least not for this reason.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01MUG92aM9m68TRc4rG55BcC
SPI+board-level smoke test: 11/11 PASS, matching the unmodified
production top exactly. 8-seed nextpnr-ecp5 P&R sweep (N=4, real
v2_board_top.lpf pins, 64MHz target): 8/8 PASS on both, open-row
variant has BETTER margin than baseline (worst 83.34 vs 76.80 MHz,
mean 90.40 vs 82.53 MHz) -- not just no regression, a real improvement.
Not yet promoted over the production fpga_neural_v2_top.v (that swap
is still pending an explicit go-ahead); this commit only adds the
verified fork + its own smoke test, additive only.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01MUG92aM9m68TRc4rG55BcC
EXP-0053: sdram_cdc_bridge.v decouples the SDRAM clock (115.2MHz, real
value derived from the board's own existing PLL VCO=576MHz, verified
via ecppll) from the 64MHz compute domain. Isolated: 137/137 tests, 0
errors, but real measured speedup is only 1.095x (not the naive 1.8x
clock-ratio estimate) -- the CDC handshake's own synchronizer
round-trip is a fixed per-transaction tax.
EXP-0054: sdram_controller_openrow.v implements the page-hit/
keep-row-open optimization sdram_controller.v's own header had always
deferred. weight_prefetch_engine_wide.v's real production traffic is
strictly sequential per job and mostly stays within one SDRAM row --
closing/reopening it every tile (today's fixed auto-precharge policy)
wastes tRP+tRCD for no reason. Isolated: 154/154 tests, 0 errors, 0
protocol violations (including the new refresh-while-row-open hazard,
fixed via an explicit precharge-before-refresh path). Real measured
speedup on the actual sequential access pattern: 1.141x.
EXP-0055: composed both, then integrated into the real D-Stress
benchmark (N=4/N=8, 256/256 bit-exact in every config). Result:
open-row ALONE gives a real, consistent ~5% cycle-count improvement
(47445/47468 vs baseline 49927/49909). CDC alone is a real ~8%
REGRESSION. Combined is still a ~4% regression -- the CDC's fixed tax
is paid on every transaction regardless of row-hit, and real D-Stress
traffic interleaves weight-fetch/activation-result access far more
than the isolated same-row test exercised, so open-row's real saving
doesn't offset it. Decision: do not adopt the CDC approach; open-row
alone is the disclosed, real win worth considering for production
next, pending an explicit go-ahead (not applied to the real board top
in this commit -- all additive, existing production RTL untouched).
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01MUG92aM9m68TRc4rG55BcC
Follow-up to EXP-0051: built sdram_controller_pipelined.v, remapping
addr->bank to low-order bits (today's weight region always maps to bank
0) and adding a shadow-slot ACTIVATE lookahead so a different-bank
request can start its tRCD wait during the current transaction's tail.
Phase A (isolated tb_sdram_controller_pipelined.v, 38/38 bit-exact,
independently re-verified this session): mechanism works, saves exactly
2 cycles (tRCD) per different-bank back-to-back pair, matching the
theoretical ceiling derived before measuring (CAS_LATENCY+BURST_LEN are
serial on the shared data bus regardless of bank, so more than tRCD/tRP
was never on the table).
Phase B (integration, tb_nms_dstress_sdram_pipelined.v, independently
rebuilt/rerun): N=4 49760 cycles (-0.33% vs baseline), N=8 49755
(-0.31%) -- both 256/256 bit-exact. Root cause of the gap: the W port's
request/ready protocol is one-at-a-time, so a second, different-bank
request is essentially never already pending while the first is still
in flight, so the mechanism rarely triggers in the real system even
though it's correct when directly stimulated. Not integrated into
production; kept as additive reference for a possible future
arbiter/backend pipelined-dispatch rewrite (out of scope here, larger
and riskier).
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01YHENedK76onD2Vtc2CMjej
Forked nms_neural_multiprocessor_sdram_unified.v + its D-Stress testbench
into a dual-bank variant (two independent sdram_unified_backend.v
instances, one for weight-fetch, one for activation+result) to test the
Fase-3 memory-bound hypothesis ahead of Phase 2. Simulation-only: the
real board (v2_board_top.lpf) still wires exactly one physical chip,
per STEP19's governing single-SDRAM mandate.
Result is honest but not the hoped-for one: splitting by traffic class
only cuts D-Stress cycles ~8-10% (N=4: 49927->45724, N=8: 49909->44980),
because the AR (activation+result) path was already lightly loaded
(~12% busy) even alone. The real ceiling is the weight-fetch channel
itself, which stays ~77-78% busy even with its own dedicated bank and
zero cross-traffic. Full writeup in experiments.log EXP-0051, including
the refined next-step options this suggests instead of a straight
2-bank board revision.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01YHENedK76onD2Vtc2CMjej
N=8 baseline (EXP-0050, real fpga_neural_v2_top + v2_board_top.lpf, fresh
8-seed sweep): 8/8 PASS at 64MHz, worst 80.97MHz, mean 84.62MHz. DSP
64/72 (88.9%) confirms real N_SLOTS=8. This directly contradicts the
brief's own premise (N8 expected to collapse to ~31MHz) and the project's
historical numbers (3-5/8 pass, worst ~55-67MHz) despite bit-identical
RTL.
Investigated and closed the same discrepancy already flagged for N=4:
logs/experiments.log:2563 explicitly tags historical Fmax numbers as
measured on "Yosys 0.68+"; this session's toolchain is Yosys 0.69+59, a
nightly dated the same day as the session -- a confirmed ~59-commit
version gap. Critical-path inspection on both N=4 and N=8 confirms the
underlying RTL congestion the project diagnosed is real and still
present (same bottleneck locations as previously documented) -- the
newer toolchain just places it well enough to still clear 64MHz.
Decision: this session's numbers are adopted as the operative baseline
for Phase 1+ (see timing.log for the full writeup). Also found, not yet
applied: slot_mem_arbiter.v/slot_mem_arbiter_wide.v both still have the
runtime-indexed-crossbar anti-pattern already fixed in neural_director.v,
sitting right on the arbiter<->backend boundary the brief names -- a
concrete Phase 1 candidate.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
New brief (N=8 timing closure, LFE5U-85F retarget, 4/8/16 x 1/2-bank SDRAM
sweep). Phase 0: no RTL changes, only measure the current baseline.
ERR-0030: constraints/v2_unified.lpf's FREQUENCY PORT "clk" was still 80MHz,
a leftover from the STEP19 freeze, never updated to the project's real
64MHz target -- fixed (LPF only, zero RTL/datapath effect).
ERR-0031 (bigger one): the first two synthesis attempts targeted
nms_neural_multiprocessor_sdram_unified.v, which is NOT the real
board-level top -- it's an obsolete wrapper only exercised by one
testbench now. The real target is fpga_neural_v2_top.v (adds the real
PLL, reset_sync, spi_host_bridge, and a second arbitration level), which
is what actually goes through synthesis+P&R for hardware. Re-targeted
correctly, matched against constraints/v2_board_top.lpf (all 17 ports
real-ball-assigned).
An N_SLOTS=8 P&R attempt against the WRONG (wrapper) target ran for 2h42m
without converging on a single seed; discarded rather than trusted.
N_SLOTS=8 baseline deferred by explicit user request until N_SLOTS=4 is
fully understood -- re-attempt against the correct fpga_neural_v2_top
target with an agreed time budget.
Result (EXP-0049, fresh 8-seed nextpnr-ecp5 P&R, real pins): N_SLOTS=4
8/8 PASS at 64MHz, worst-seed 81.20MHz, mean 91.05MHz. Higher than
DEC-0042's historical worst/best (64.55/77.21MHz) despite identical RTL --
disclosed, unresolved (leading hypothesis: nextpnr-ecp5 build/version
difference), adopted as the operative baseline for this session's
toolchain going forward. Full writeup in errors.log/timing.log/
experiments.log (EXP-0049).
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
The repository had accumulated multiple, contradictory "current state"
documents for V2 hardware: an old V1 IT/EN datasheet copy nested inside
hardware/v2/docs/datasheet/, a stray untracked duplicate at repo root
(docs/DatasheetLatex/), and a second, much older documentation track
(hardware/v2/docs/*.md: PRE_PCB_VERIFICATION.md, PRE_PCB_CLOSURE_4POINT.md,
MEMORY_UPGRADE_64MB_N8.md, and 10 more) describing an earlier PSRAM/
N_SLOTS<=2 milestone alongside the real, current SDRAM/N_SLOTS=4 board.
The LaTeX datasheet's own front matter (features/pinout cover pages) and
chapter 9 (benchmarks) were themselves still describing that obsolete
architecture, contradicting the real, current chapters 5/7/10 elsewhere
in the same document.
This commit:
- Flattens hardware/v2/docs/datasheet/files/docs/datasheet/v2-en/* up to
hardware/v2/docs/datasheet/ (was 4 levels of redundant nesting).
- Removes the old V1 IT/EN LaTeX copies and the stray root-level
duplicate entirely (recoverable from git history, not from disk).
- Preserves the real component reference PDFs (ECP5 eval board, ISSI
PSRAM, programming cables) under datasheet/references/.
- Removes 13 superseded hardware/v2/docs/*.md status documents after
folding every real, unique fact they contained into the datasheet:
SPI max verified clock (12MHz, exact 12.8MHz CDC edge), SDRAM directed
boundary test (21/21 PASS), 16MHz oscillator MPN (ECS-3225MV-160-BN-TR),
and the real FPGA<->SDRAM ball mapping cross-check.
- Rewrites the datasheet's own front matter, ch.4 (parameters), ch.8
(top-level module -- was documenting the wrong, non-physical top
entirely), and ch.9 (benchmarks) to describe the current, real SDRAM/
N_SLOTS=4 production board, while keeping the real PSRAM-era chapters
as clearly-labeled history rather than deleting correctly-measured
work.
- Fixes a title-page tikzpicture that was clipped off the page edge
(pre-existing, unrelated to this change) by scaling it to fit.
Net: 85 files changed, -8814/+498 lines. hardware/v2/docs/ now contains
exactly one current datasheet plus FIRST_POWER_ON.md (a bring-up
runbook, not a duplicate spec).
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_013xXuuRUWZScuo1DeYJxs3v
Removed session-log/conversational register leftover from the
interactive drafting process ("the user's own suggestion", "user
confirmed", "user-authored schematic", "user-requested optimizations",
etc.) and replaced with neutral, factual engineering-document
phrasing. No technical content changed -- attribution language only.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_013xXuuRUWZScuo1DeYJxs3v
Exported the schematic (kicad-cli sch export pdf) and BOM (kicad-cli sch
export bom) directly from the real KiCad source instead of relying on
pasted screenshots/CSVs, then updated ch.10 accordingly:
- New "Real KiCad schematic capture" section embeds the two live sheets
(FPGA, UnusedBank) as vector figures pulled straight from the project
file, plus a note on the three sheet files not reachable from the
root hierarchy.
- Boot-flash net-name mismatch finding confirmed resolved: FPGA_SPI_*
labels now match exactly on both the flash chip and the ECP5's
dedicated MSPI pins.
- FPGA grade fix (8BG381I -> 8BG381C) now verified directly in the
source file's Value field, not just as a stated intent. Real package
geometry added: 0.8mm pitch, 20x20 array, 17x17x1.76mm body.
- New minor finding: U2's footprint library folder is still named
..._8BG381I even though the Value field is corrected -- not
board-affecting (identical physical footprint across grades), but
flagged for a future rename.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_013xXuuRUWZScuo1DeYJxs3v
User confirmed LFE5U-45F-8BG381C (commercial) is the intended part,
matching every other reference in this project. Also corrects this
chapter's own earlier temperature figures: commercial grade is real
TJ 0 to +85C, industrial is TJ -40 to +100C (an earlier draft of this
section had the industrial range wrong at -40/+85C). Same "-8" speed
grade in both -- the letter suffix only changes the characterized
temperature range. KiCad library still needs the part number itself
corrected from ...381I to ...381C.
Compiled clean (47 pages, 0 errors).
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_013xXuuRUWZScuo1DeYJxs3v
User confirmed TLV62568 (U1) outputs 1.1V, explaining the +1V1 label
found near the VCCAUX ferrite (L2) during the schematic review: it
belongs to U1's own real output net, merely nearby on the page layout,
not routed through the ferrite. VCCAUX remains 2.5V as required by the
real Lattice datasheet.
All three schematic "open items" from the earlier review are now
resolved: TLV62568 EN (R3=499k, confirmed via BOM), the +1V1 label
(false alarm, explained above), and the JTAG pull-up array (confirmed
8 discrete 0402 parts via BOM, not a bussed package -- no polarity
limitation). Only the boot-flash net-name typo (FGPA/FPGA + SCLK/CLK)
remains as a real, open schematic fix, and the FPGA grade discrepancy
(8BG381I vs 8BG381C) remains to be confirmed.
Compiled clean (47 pages, 0 errors).
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_013xXuuRUWZScuo1DeYJxs3v
User confirmed the real schematic has SDRAM CAS#=F7/WE#=F9 -- matches
this chapter exactly. The earlier review's "appear swapped" finding
was a misread of the schematic image, not a real error; moved from
"real findings" to a cleared checked-item note.
TLV73325's EN pin resolved: direct wire to +3.3V (VIN), always-enabled
-- no soft-start timing requirement like TLV62568's own R3 pull-up (a
plain LDO, no sequencing note in TI's own datasheet), and no dynamic
enable/disable control exists elsewhere in this design.
Remaining real, open finding: the boot-flash net-name mismatch
(FGPA/FPGA typo + SCLK/CLK) still needs a schematic fix.
Compiled clean (47 pages, 0 errors).
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_013xXuuRUWZScuo1DeYJxs3v
Real KiCad-exported BOM added to the hardware chapter, cross-checked
against every component value this chapter already specifies -- most
match exactly (R1/R2 feedback divider, L1/L2, ferrite part number, all
three real ICs). One real discrepancy found: U2 is captured as
LFE5U-45F-8BG381I (industrial grade) while every other reference in
this project uses the C (commercial) grade part -- flagged, not
resolved, needs explicit confirmation.
Also resolves three earlier open items from the schematic review:
R3=499k confirms TLV62568's EN is populated; R5-R12 being 8 discrete
0402 resistors (not a multi-resistor array) confirms the JTAG
pull-up/down polarity concern doesn't apply; U5 confirms the
previously-missing 16MHz oscillator is now present.
Compiled clean (47 pages, 0 errors).
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_013xXuuRUWZScuo1DeYJxs3v
Adds a dated review section recording today's actual schematic check
against every real ball assignment in this chapter: confirmed-correct
items, two real findings needing correction (boot-flash net-name
mismatch FGPA/FPGA typo + SCLK/CLK label mismatch that would leave the
flash electrically disconnected from the ECP5's config engine; SDRAM
CAS#/WE# appearing swapped vs. the verified F7/F9 assignment), and
open items not resolvable from the schematic image alone (regulator EN
pins, a stray +1V1 label near the VCCAUX ferrite, JTAG pull-up/down
array polarity).
Also reserves a "PCB module form factor" section (castellated-edge SMD
module, ~50x25mm) for the future physical layout.
Compiled clean (46 pages, 0 errors).
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_013xXuuRUWZScuo1DeYJxs3v
Datasheet and pinouts.md updated to the current, real state after
today's session: flash #1 was implemented then removed (user's own
MHz-over-persistence priority call), the clock-closure table now
shows the post-revert, post-DEC-0042 numbers (N_SLOTS=4 @ 64MHz 8/8,
worst 64.55MHz/best 72.37MHz; N_SLOTS=8 deferred by explicit user
request), and the FPGA_DATA_READY any_pending formula is updated to
the real counter-based implementation (credited to the user's own
diagnosis) that fixed the last failing N=4 seed.
Compiled clean (45 pages, 0 errors).
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_013xXuuRUWZScuo1DeYJxs3v
Real critical-path trace after the flash #1 revert showed a NEW
bottleneck (neural_director.job_out_slot -> dependency_manager.
node_resolved/node_state, 76-84% routing) distinct from every prior
fix this session -- already a flat, parallel 64-way compare, not a
serial chain, so the established restructuring fix class doesn't
apply. Root cause: any_pending (added for FPGA_DATA_READY) reads
node_state[0:N_NODES-1] combinationally every cycle, adding real
fan-out onto the same congested signal.
User's own suggestion: replace the combinational scan with a
synchronous up/down counter. pending_count +1 on registration
acceptance, -1 on dispatch acceptance; any_pending = (pending_count
!= 0) -- mathematically identical (DEC-0008: nodes never reclaimed
mid-run) but reads one small register instead of scanning a 16-wide
array every cycle.
Verified: D-Stress N=4 bit-exact (49927 cycles, data_ready PASS).
Fresh 8-seed P&R: N_SLOTS=4 @ 64MHz now 8/8 PASS (was 7/8 after the
flash revert), worst seed1 64.55MHz, best seed0 72.37MHz.
See decisions.log DEC-0042.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_013xXuuRUWZScuo1DeYJxs3v
Closes the flash #1 RTL gap flagged in DEC-0041: real, unmodified V1
subsystem (flash_slot_manager.v/flash_copy_engine.v/spi_flash_master.v/
crc32.v) now instantiated in fpga_neural_v2_top.v, bridged to the AR
memory bus via a new flash_mem_adapter.v (byte<->word, matches
nms_memory_manager_stream_wide.v's own real masking convention), and
commandable over SPI via a new spi_host_bridge.v opcode (OP_FLASH_CMD,
0x30) using the same byte-counting idiom as OP_WRITE_JOB. Real balls
now in the LPF: flash_sclk=B2, flash_mosi=E2, flash_miso=F2,
flash_cs_n=F3.
New tb_flash_integration_smoke.v: real SPI-triggered OP_FLASH_READ_BLOCK
verified bit-exact (64/64 bytes) against a real V1 flash_model.v
instance, through the new adapter and the widened (2->3 port) host-arb
arbiter; WRITE_JOB regression confirms the new 3rd port doesn't disturb
existing traffic. Full existing regression re-run clean: D-Stress N=4/
N=8 (bit-exact + data_ready PASS), board-level smoke test (11/11),
isolated spi_host_bridge test (18/18).
Honest, disclosed finding: a full 8-seed P&R re-verification shows
N_SLOTS=4 @ 64MHz regressed from 8/8 to 3/8 PASS (worst 60.18MHz).
Root cause traced via the real critical-path report: the SAME
pre-existing arbiter-to-sdram-backend bottleneck already documented all
session, made worse by flash's added die-area placement pressure --
not a new path through the flash logic itself. N_SLOTS=8 essentially
unchanged (6/8, was 5/8). See decisions.log DEC-0042 for full detail
and open decision points.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_013xXuuRUWZScuo1DeYJxs3v
Found while helping verify the user's own schematic: clk_sys (the PLL-
generated 64MHz system clock) was purely internal to
fpga_neural_v2_top.v -- never reached a physical output pin. The real
external SDRAM chip cannot function without its own CLK input driven
from the board; this was missing from every prior P&R run this
session, none of which ever routed a real clock to the SDRAM interface.
Added `sdram_clk` output port (driven directly by clk_sys), assigned
to J4 (bank 6, GR_PCLK6_0 -- a real clock-capable ball, confirmed free
via Trellis iodb.json). Verified via real synthesis (0 errors) and
nextpnr-ecp5 place&route: the pad-forwarded clock merges with the
existing internal clock net (as expected, both are the same clk_sys
signal), achieving 66.61 MHz post-route -- PASS at the 64 MHz target
(the pre-route estimate of 49.73 MHz was a placement-only pessimistic
number, superseded by the real post-route result). Smoke test
re-verified (tb_fpga_neural_v2_top_smoke.v, 11/11 PASS).
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_013xXuuRUWZScuo1DeYJxs3v
Adds a real, dated section to ch.10 (Hardware and board) covering the
two-independent-flash architecture (neural-network data vs. boot
bitstream), the ESP32<->ECP5 JTAG-only link, and the real CABGA381
ball assignments (JTAG/PROGRAMN/INITN/DONE/CFG[2:0]/MSPI dedicated
pins), matching decisions.log DEC-0041.
Also closes ch.7's (Host interface) own long-standing "still needed"
list: the physical transport (spi_host_bridge.v) and the completion-
notification path (FPGA_DATA_READY) it used to flag as missing are
both now real -- described with the same system-idle-detector formula
implemented in the RTL.
Compiled clean (44 pages, 0 errors).
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_013xXuuRUWZScuo1DeYJxs3v
Establishes the real ESP32<->ECP5 programming architecture: flash #1
(neural-network data, existing V1 subsystem, ball reserved not yet
wired into V2) stays separate from flash #2 (boot bitstream, MSPI
auto-boot, CFG[2:0]=[0,1,0]); ESP32 talks JTAG only (bit-banged, no
hardware JTAG-master peripheral on S3/C6), updating flash #2 through
the ECP5's own internal sysCONFIG-to-SPI bridge, never driving the
flash pins directly -- zero bus contention, confirmed against the real
Lattice hardware checklist and sysCONFIG user guide.
Adds real, verified ball assignments (official Lattice CABGA381 CSV +
Project Trellis iodb.json) for JTAG, PROGRAMN/INITN/DONE, CFG[2:0],
and the MSPI dedicated pins -- all written to docs/pinouts.md.
Implements FPGA_DATA_READY as real RTL: a system-idle detector
(dependency_manager's any_pending OR neural_director's !queue_empty OR
any active slot), sticky on the busy->idle edge, self-clearing on new
work -- not a per-neuron completion pulse, which was confirmed too
fine-grained. Bit-exact regression re-verified at N_SLOTS=4 and 8
(zero cycle-count change), new explicit data_ready assertion check
added to the D-Stress testbench (PASS both configs), and a fresh
Yosys+nextpnr-ecp5 placement check (0 errors, data_ready placed at G3).
Also fixes a real, independently-found bug while editing an adjacent
file: nms_neural_multiprocessor_sdram_unified.v's own sdram_a port was
still [11:0] (12 bits), stale from before the 64MB/13-bit memory
upgrade. Not exercised by the real board-level top (which wires SDRAM
directly, bypassing this wrapper) but WAS silently truncating A12 in
every D-Stress simulation this session, including today's earlier
ERR-0029 verification runs. Assessed impact: all D-Stress test
addresses used this session decode to rows under 4096 (bit 12 never
actually needed), so no false-positive PASS is believed to have
resulted -- but the full 64MB space was never actually exercised
through this wrapper. Fixed; re-verified bit-exact with identical
cycle counts.
See decisions.log DEC-0041 for full detail.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_013xXuuRUWZScuo1DeYJxs3v
hardware/v1/ was created (dc0b331) as a frozen snapshot of the V1
project that then lived at the repo root (rtl/, sim/, synth/, tools/,
docs/). Root received zero further commits to those files after the
freeze -- confirmed byte-identical to the hardware/v1/ copy for every
file removed here. Root was the "before", hardware/v1/ is the
curated, canonical "after".
Removed (all verified exact-hash duplicates of hardware/v1/ content):
- rtl/ (20 files, 100% covered by hardware/v1/rtl/)
- tools/{netasm,pinout,run_regression.py,flash_catalog,validation,
fpga_benchmark.py} (19 files, 100% covered by hardware/v1/tools/;
tools/neural_sim/ kept -- unique, post-freeze, no counterpart)
- sim/*.v (47 testbenches, 100% covered by hardware/v1/sim/; the
~38 remaining sim/ entries are compiled binaries and .vcd
waveform dumps, left as a separate cleanup decision)
- synth/ecp5/{p2,p4,p8,post_fix_verify} (25 files, exact duplicates
of hardware/v1/synthesis/; the other ~84 synth/ecp5/* experiment
build directories are historical artifacts never carried into the
freeze, left as a separate decision)
- WORKLOG.md (duplicate of hardware/v1/docs/WORKLOG.md)
- docs/{FPGA-Neural-Datapatch-Benchmark,FPGA-Neural-Hardware-Design,
FPGA-NeuralNetwork-Engine}.md, docs/validation/*.md (18 files),
docs/FPGA-Neural-Datasheet-{EN,IT}.pdf -- all exact duplicates of
hardware/v1/docs/ content
- hardware/v1/docs/DatasheetLatex/ (24 files) -- exact duplicate of
hardware/v2/docs/datasheet/files/docs/datasheet/en/ (discovered
during this audit; not the same DatasheetLatex already removed
from hardware/v2/docs/ in an earlier commit)
Moved (genuine, unique, post-freeze V2 content -- not duplicated
anywhere, just living in the wrong/legacy root docs/ location):
- docs/architecture/*.md -> hardware/v2/docs/architecture/
- docs/pinouts.md, docs/FPGA_NEURAL_V2_DATASHEET.md,
docs/FPGA_NEURAL_V2_SCHEMATIC.md,
docs/FPGA-Neural-V2-Datasheet-EN.pdf -> hardware/v2/docs/
Left untouched (separate decisions, not part of this cleanup):
- docs/FPGA-Neural-Flash-Subsystem-Verification.md, docs/
v2-description.md -- orphaned root-only content, no duplicate
found anywhere, but also not part of the reviewed plan
- synth/ecp5/* experiment dirs and sim/*_sim + sim/*.vcd build
artifacts -- not literal duplicates, flagged as candidates for a
future, separate cleanup pass
Verified no functional breakage: grepped all remaining scripts/docs
for references to every removed path -- only prose/comment mentions
found, no executable imports or build-script paths broken.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_013xXuuRUWZScuo1DeYJxs3v
Replaced by the just-versioned hardware/v2/docs/datasheet/ (the
project's real, maintained IT+EN LaTeX datasheet, now including the
2026-09-07 SDRAM upgrade addendum). DatasheetLatex/ was a separate,
differently-structured, stale LaTeX document living in the same
location -- removed to avoid two competing datasheets under
hardware/v2/docs. hardware/v1/docs/DatasheetLatex/ is untouched (V1
scope, not part of this request).
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_013xXuuRUWZScuo1DeYJxs3v
Was a separate, untracked directory (DataSheet/) outside the repo.
Renamed to lowercase and moved in as hardware/v2/docs/datasheet/, with
its own .gitignore for LaTeX build byproducts (compiled PDFs stay
tracked, .aux/.log/.toc/etc do not). Now versioned and shares this
repo's own remote instead of living untracked on disk.
Content: IT+EN LaTeX chapter sources, reference manufacturer PDFs, and
compiled datasheet PDFs including the 2026-09-07 SDRAM upgrade
addendum (AS4C32M16SB-7BIN part/pinout/timing) in the v2-en chapters.
Note: hardware/v2/docs/DatasheetLatex/ (and the v1 sibling) is a
separate, already-tracked, differently-structured LaTeX document that
predates this move -- left untouched, not merged, since its chapter
set and content differ and merging was not requested.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_013xXuuRUWZScuo1DeYJxs3v
Replace the serial "last-match-wins" priority-scan hit-index encoder
with a flat one-hot compare + single-level priority encode, breaking
the serially-dependent PFUMX/OFX cascade real P&R showed dominating
the N_SLOTS=8 @ 64MHz critical path (55.84MHz worst, 4/8 seeds PASS).
Real nextpnr-ecp5 re-verification (32-run matrix, 4 configs x 8 seeds):
N_SLOTS=8 @ 64MHz improves to 5/8 PASS (worst 60.12MHz, up from
55.84MHz). N_SLOTS=4 @ 64MHz stays 8/8 PASS but with reduced worst-case
margin (WNS +0.605ns, down from +2.143ns) as the critical path
relocates to a different, previously-second-worst path in the same
module -- a real, disclosed trade-off, not hidden. 80MHz remains NO-GO
at both processor counts (re-confirmed on the fixed RTL).
Bit-exact, zero functional regression: isolated
tb_sdram_unified_backend.v (40/40) and full D-Stress N=4/N=8 (both
256/256 neurons bit-exact vs golden model).
See errors.log ERR-0029 and decisions.log DEC-0040 for full root-cause
writeup and MEMORY_UPGRADE_64MB_N8.md section 10 for the complete
measured data set and AS4C32M16SB-7BIN pinout tables.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_013xXuuRUWZScuo1DeYJxs3v
Adds the consolidated, authoritative record for the 64MB memory
upgrade and N_SLOTS=8 investigation (real datasheet family comparison,
RTL changes, both timing fixes with real P&R data, honest N=8 clock-
closure status, real DigiKey availability for the frozen part).
Marks HARDWARE_FREEZE.md/MEMORY_ARCHITECTURE.md/PRE_PCB_VERIFICATION.md/
PRE_PCB_CLOSURE_4POINT.md's own SDRAM-specific sections as superseded
(they describe the previous 8MB AS4C4M16SA-6TIN part) with pointers to
the new document, rather than rewriting each individually.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_013xXuuRUWZScuo1DeYJxs3v
Memory upgrade, at the user's own explicit request: Alliance Memory
AS4C4M16SA-6TIN (64Mbit/8MB) -> AS4C32M16SB-7BIN (512Mbit/64MB, 54-ball
TFBGA), the largest same-family SDR SDRAM Alliance Memory offers.
Real-datasheet-driven (whole AS4C4M16SA/AS4C8M16SA/AS4C16M16SA/
AS4C32M16SA family investigated): 13 row bits (was 12, one new FPGA
pin sdram_a[12]/ball F1), 10 column bits (was 8), real -7-grade AC
timing (tRCD/tRP improved to 15ns, tREFI halved to 7.8us for the
doubled row count). sdram_controller.v and sdram_model.v gained real
ROW_BITS/COL_BITS/BANK_BITS parameters (was hardcoded 12/8/2).
ADDR_WIDTH widened 23->26 bits across the live instantiation tree.
This required a real SPI protocol change (spi_host_bridge.v): a 26-bit
byte address no longer fits in 3 bytes -- every address field widened
3->4 bytes (WRITE_JOB 15->18 payload bytes, WRITE_MEM/READ_MEM header
5->6 bytes).
Found and fixed two real timing regressions via nextpnr-ecp5 P&R
(not assumed): neural_director.v's own runtime-indexed demux write
(ERR-0027, was silently synthesizing an extra MULT18X18D) and
nms_activation_fill_ctrl_v3.v's own linear N_SLOTS-wide max-scan
(ERR-0028, became dominant at N_SLOTS=8) -- both replaced with
constant-indexed/tree-based equivalents, bit-exact same behavior,
confirmed via full D-Stress N=2/4/8 regression (identical cycle
counts). N_SLOTS=4 now fully closes timing at 64MHz (8/8 seeds);
N_SLOTS=8 significantly improved but not yet fully reliable (5/8
seeds) -- honestly disclosed, not claimed complete.
Full regression re-verified: sdram_controller (461/461, 18 configs),
tb_sdram_boundary (21/21), D-Stress N=2/4/8 (bit-exact), spi_host_bridge
(18/18), board-level SPI smoke test (11/11), unified backend (40/40).
See hardware/v2/docs/MEMORY_UPGRADE_64MB_N8.md for the full
investigation, and errors.log/decisions.log (ERR-0027, ERR-0028,
DEC-0039) for the complete root-cause writeups.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_013xXuuRUWZScuo1DeYJxs3v
Adds tools/neural_sim/, a NumPy-based reference implementation of the
FPGA-Neural V2 numeric model (INT8 in/weight, 32-bit wraparound
accumulation, ReLU+saturate out), derived directly from
hardware/v2/rtl/neural_processor.v (not assumed) and reusing
tools/validation/mac_oracle.py's own pre-existing, hand-verified
two's-complement primitives rather than duplicating them.
Provides: neuron/layer/network models, a logical memory model of the
real V2 SDRAM map (weights/activations/results), deterministic
test-vector generators (simple/signed/extremes/zero/random/D-Stress
256x128) with JSON golden-vector export, an FPGA-vs-Python bit-exact
comparison utility, four example networks, a CLI
(`python -m tools.neural_sim ...`), and a 96-test pytest suite (all
passing) covering signed-arithmetic edge cases (including a direct
32-bit wraparound proof), scalar-vs-vectorized neuron cross-checks,
layer/memory/vector/comparison tests.
This is a golden functional reference (bit-exact numeric result),
explicitly NOT a cycle-accurate FPGA simulator -- see
tools/neural_sim/README.md for the full scope statement.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_013xXuuRUWZScuo1DeYJxs3v
PRE-PCB CLOSURE Point 1: adds tb_sdram_boundary.v, a directed (not
randomized) regression covering address 0/1/last/last-1, an explicit
row-boundary crossing, all 3 inter-bank boundary crossings, the real
V2 memory-map region boundaries (weights/activations/results), and
every DQM byte-mask combination with explicit read-after-write.
21/21 PASS at both 64MHz and 166MHz, zero bugs found.
PRE-PCB CLOSURE Point 2: adds tb_spi_freq_sweep.v, a reproducible SPI
bit-rate sweep against the real fpga_neural_v2_top (osc_clk driven at
the real 64MHz clk_sys rate via the SIM PLL bypass). Found and fixed a
race in the new test harness itself (a fixed-time wait before reading
a WRITE_MEM/READ_MEM response, too short whenever a periodic AUTO
REFRESH delayed the backend) -- not a spi_host_bridge.v defect,
confirmed against tb_spi_host_bridge.v's own isolated regression.
Determined the real, deterministic CDC margin: the synchronizer
requires >=5 system-clock cycles per SPI bit (exactly 64MHz/5 =
12.8MHz); recommends SPI_MAX_VERIFIED=12MHz with real margin below
that hard edge.
Full writeup: hardware/v2/docs/PRE_PCB_CLOSURE_4POINT.md.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_013xXuuRUWZScuo1DeYJxs3v
Adds hardware/v2/docs/PRE_PCB_VERIFICATION.md as the single
authoritative pre-schematic verification record: RTL/ERR-0025/
regression re-verification, clock/reset, synthesis/P&R re-audit,
setup/hold timing status, the real SDRAM datasheet-parameter audit
table (Alliance Memory AS4C4M16SA-6TIN Table 17), SPI host bridge
protocol documentation, FPGA power/pinout tables, first-board bring-up
and benchmark status, and cross-domain consistency audit.
Freezes the FPGA configuration flash: Winbond W25Q32JVSSIQ (32Mbit,
SOIC-8, 2.7-3.6V, standard SPI, ECP5 Master-SPI-boot compatible) --
this was the one section-11 item the governing mandate required not
be left OPEN.
Marks CHIP_READINESS.md/OPEN_ITEMS.md/PINOUT.md/CLOCK_ARCHITECTURE.md/
POWER_ARCHITECTURE.md/SCHEMATIC_READINESS.md as superseded (they
predate the SPI host bridge, PLL, and this session's SDRAM datasheet
audit) with pointers to the new consolidated document, rather than
rewriting each individually.
Updates the V2 LaTeX datasheet's status/roadmap chapter to reflect the
SDRAM datasheet audit and configuration-flash decisions, rebuilds the
PDF (clean compile, 16 pages).
Classification: PRE-PCB VERIFIED. Schematic and PCB implementation
remain user-owned and not started.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_013xXuuRUWZScuo1DeYJxs3v
Real Alliance Memory AS4C4M16SA-6TIN datasheet (Rev 5.0, Table 17)
specifies tMRD as a fixed 2-tCK cycle count, not an ns value.
sdram_controller.v modeled it via ns_to_cycles(12), which rounded to
2 cycles by coincidence at every previously-tested frequency
(100/133/166MHz) but rounds to only 1 cycle at the real 64MHz board
target -- an under-provisioned one-time init sequence. Fixed by
hardcoding T_MRD=2, matching how CAS_LATENCY is already modeled.
Verified zero regression: full 9-config legacy sweep + a new
dedicated 64MHz config (461/461 PASS each), N=2/N=4 D-Stress
(identical cycle counts), board-level smoke test (11/11 PASS).
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_013xXuuRUWZScuo1DeYJxs3v
Real synthesis and place-and-route of the actual final board-level
top (fpga_neural_v2_top.v -- SPI bridge, real EHXPLLL, reset_sync,
compute+memory core), against a real, fully ball-assigned LPF. Also
ports the V2 datasheet to LaTeX using V1's own preamble/macros/
typography, and records a real (non-ESP32, honestly labeled) software
reference comparison.
Synthesis (Yosys, real run): 0 CHECK-pass problems, 38 unique warnings
(43 total), all matching this project's own previously-reviewed benign
set (neural_processor.v's known genvar multi-driver artifact, small-
array-to-register unrolling, the real SDRAM DQ tristate bus) -- no new
warnings from the SPI bridge, PLL, or reset synchronizer.
TRELLIS_FF=6322, TRELLIS_COMB=7084, MULT18X18D=32, EHXPLLL=1 (real PLL
confirmed present), DP16KD=0 (all small SRAMs -> distributed RAM).
Place-and-route (nextpnr-ecp5, real runs, 8 seeds, new
v2_board_top.lpf with all 44 top-level signals ball-assigned from the
official Lattice pinout CSV -- no placeholders): 8/8 PASS at 64MHz.
Worst 68.51MHz (seed 4), best 74.17MHz (seed 7), mean 71.16MHz. Zero
unrouted nets, zero placement/routing errors, TRELLIS_IO=44/245 (17%).
Critical path alternates between dependency_manager's own priority
encoder and sdram_unified_backend's own weight-cache hit-index logic,
matching this project's own prior documented timing investigations --
not a new defect.
New: hardware/v2/constraints/v2_board_top.lpf (final LPF, supersedes
v2_unified.lpf for the board-level top), hardware/v2/reports/
step_final_{synthesis,pnr_worst_seed4,timing}.* (raw evidence),
hardware/v2/docs/DatasheetLatex/ (V2 datasheet, real LaTeX build,
16 pages, visually inspected, ported from hardware/v1/docs/
DatasheetLatex/'s own preamble and macros).
Real, honestly-labeled software baseline: the D-Stress arithmetic
(256 neurons x 128 INT8 MACs) compiled and run on THIS development
machine (Apple M4, arm64, NOT an embedded target, NOT ESP32) --
1.28us/inference, included in the datasheet with an explicit
disclosure that no physical ESP32 hardware was available for a real
embedded-target comparison.
Remaining, disclosed, NOT-yet-closed items (this commit does NOT
claim silicon readiness): real KiCad schematic + ERC, PCB layout,
sourced BOM, real power current-budget estimate, SDRAM-datasheet-
parameter cross-check, configuration-flash selection, and (necessarily)
physical fabrication/bring-up. See hardware/v2/docs/DatasheetLatex/
chapters/08-status-roadmap.tex for the complete, itemized checklist.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_013xXuuRUWZScuo1DeYJxs3v
Root-causes and fixes the real, disclosed defect left open at the end
of the previous STEP20 commit: the board-level SPI host interface
produced wrong compute results when jobs were dispatched with
realistic (widely time-separated) pacing, even though job registration
itself was already confirmed correct at the dependency_manager
handshake.
Root cause: nms_weight_packed.v and nms_activation_replicated.v both
used a REGISTERED SRAM read (rd_data_reg <= mem[addr], one full clock
of latency), but nms_memory_manager_stream_wide.v's own read-ahead
pipeline (its `rd_pending` bit) is designed around a COMBINATIONAL
read -- a request issued this cycle produces data already valid to
capture the very next cycle. A busy, multi-tile job (e.g. the STEP19
D-Stress regression, 16 tiles/neuron) never exposes the mismatch,
since its own weight/activation prefetch always runs far enough ahead
that any given tile has been sitting stable in the SRAM for many
cycles by the time it's actually consumed. An uncontested single-tile
job has zero such margin: its one tile's read fires on the exact edge
the data nominally becomes ready, landing squarely on the missing
cycle and permanently latching stale/zero data.
Fixed by making both SRAMs' reads combinational, with an explicit
same-cycle fill/read address-match bypass for the one hazard a plain
combinational read alone would still miss. No FSM, arbiter, or SDRAM
controller logic was touched.
Verified (Verilator, per this project's own standing DEC-0004
protocol):
- tb_fpga_neural_v2_top_smoke.v: 11/11 PASS -- single job, back-to-back
jobs, a realistic ~85us-gap job pair, and a parametric sweep of
inter-job gaps (100ns/5000ns/50000ns).
- STEP19 D-Stress N=2: 49788 cycles, 256/256 bit-exact -- identical
cycle count to before this fix (zero regression).
- STEP19 D-Stress N=4: 49771 cycles, 256/256 bit-exact -- identical
cycle count to before this fix (zero regression).
- tb_sdram_unified_backend.v (40/40) and tb_spi_host_bridge.v (18/18)
reconfirmed unaffected.
The physical SPI host interface is now verified correct end-to-end.
Real synthesis/P&R of the board-level top (fpga_neural_v2_top.v) is
the deliberate next step, not yet performed this round.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_013xXuuRUWZScuo1DeYJxs3v
STEP20 work toward the V2 hardware release gate. Adds real new RTL
implementing the three pieces the previous freeze (V2.0.0) explicitly
left open, plus real, disclosed verification findings. Does NOT
declare hardware release complete -- see below.
New RTL:
- spi_host_bridge.v: real SPI slave protocol engine (WRITE_JOB/
WRITE_MEM/READ_MEM/STATUS/RESET opcodes), replacing the 110-pin
reg_* testbench bus as the intended physical host interface.
Isolated regression 18/18 PASS (tb_spi_host_bridge.v); two real
MISO-timing bugs found and fixed during its own development (see
the module's header for the root-cause writeup).
- ecp5_pll_sys_clk.v: real, tool-generated (Project Trellis ecppll)
EHXPLLL wrapper, 16MHz oscillator -> 64MHz system clock, with a
declared (not fabricated) simulation-only PLL bypass.
- reset_sync.v: standard async-assert/sync-deassert reset bridge
gating on external POR and PLL lock.
- fpga_neural_v2_top.v: board-level top wiring the above around the
STEP19 compute+memory design's own already-frozen submodules
(zero modification to neural_processor.v, dependency_manager.v,
sdram_unified_backend.v, or any other previously-frozen file).
Real findings from this step's own re-verification (both logged in
full in hardware/v2/logs/errors.log):
- ERR-0024: the current Icarus Verilog v13.0 install (updated since
the last freeze) gives WRONG bit-exact results for the
already-committed STEP19 regression. Cross-checked against
Verilator per this project's own standing protocol (DEC-0004) --
the STEP19 baseline (single SDRAM, N=2/N=4, raw reg_* interface) IS
bit-exact correct, reconfirmed today, matching the historical cycle
counts exactly. Two provably-zero-behavior-change declaration-order
fixes were required just to get the current toolchain to elaborate
the already-shipped STEP19 files at all.
- ERR-0025: a real SPI-bridge protocol race (fixed) plus a SEPARATE,
real, UNRESOLVED defect -- two jobs dispatched through the real SPI
path with realistic pacing produce wrong compute results, even
though job registration itself is confirmed correct at the
handshake. Root cause not yet isolated. Committed as a known-failing
regression (tb_fpga_neural_v2_top_smoke.v) documenting the gap
honestly rather than hiding it.
Given ERR-0025 Part B is real and unresolved, synthesis/P&R of the new
board-level top was deliberately not attempted this round, and V2
hardware release is NOT declared complete. See decisions.log DEC-0036
and hardware/v2/docs/{CHIP_READINESS,OPEN_ITEMS}.md for the full,
itemized status.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_013xXuuRUWZScuo1DeYJxs3v
FASE #1 hardware freeze for FPGA-Neural V2, N4/P8, single external
SDRAM (Alliance Memory AS4C4M16SA-6TIN) serving weights, activations,
and results through one physical sdram_controller.v instance. Removes
the PSRAM dependency (hardware/v1/rtl/psram_controller.v +
memory_interface.v) from the V2 physical path entirely -- V1 itself
remains fully unmodified, the golden reference.
New RTL: sdram_unified_backend.v (2-way W/AR arbitration over one
SDRAM controller, real per-byte DQM write masking added to
sdram_controller.v for correct single-byte result writes with no
read-modify-write), nms_neural_multiprocessor_sdram_unified.v (the
frozen top-level). Two real bugs found and fixed via full-system
testing before being accepted (ERR-0023): a deadlock and an off-by-one
data-shift bug in the new arbitration logic.
Real results: N=4 and N=2 D-Stress bit-exact (256/256 neurons), 40
real AUTO REFRESH events interleaved with zero corruption, real
Yosys+nextpnr-ecp5 synthesis/P&R for LFE5U-45F-8CABGA381 (149/245
TRELLIS_IO, a real 45-pin reduction from the prior dual-memory
design). Timing is MARGINAL (1/8 P&R seeds >=80MHz), reported honestly
rather than masked by the best seed.
Real, sourced ball-level pinout for the SDRAM bus + clk/rst (39/149
signals, P&R-verified) using the official Lattice ECP5U-45 pinout CSV
found on disk during this step's own pre-commit review -- corrects an
earlier draft that wrongly assumed no real pinout data was available.
Chip readiness: NO. Real, disclosed blockers remain (no physical host
interface exists yet -- the RTL's own reg_* ports are a 110-pin raw
test-harness bus; clock source/PLL decision; power/configuration
component selection) -- see hardware/v2/docs/{HARDWARE_FREEZE,
CHIP_READINESS,OPEN_ITEMS}.md for the complete, itemized status.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_013xXuuRUWZScuo1DeYJxs3v
Implements optimization #2 from the final benchmark campaign's own
recommendation, on top of DEC-0015's word-level burst rewrite: a new
shared activation_cache.v module fetches a given activation (X)
vector from PSRAM once instead of once per neuron sharing it - the
exact redundant traffic pattern the dense-layer workloads in this
project's benchmark suite exhibit.
Each memory_manager's own prefetch_engine now fetches WEIGHTS only;
the activation half is requested from the shared cache instead
(single-tag, tile-granular, N_SLOTS request ports, its own real
word-level PSRAM backend via a new dedicated arbiter port).
dataflow_core.v/slot_mem_arbiter.v/neural_multiprocessor.v widened to
N_SLOTS+1 ports to arbitrate the cache's traffic alongside each
slot's weight traffic.
Two real bugs found and fixed during implementation (ERR-0010): a
target-bank/pending-bank race in memory_manager.v's activation-cache
wiring (the same bug class ERR-0006 already fixed once for
pf_target_bank - a later handoff's queued request can overwrite which
bank an earlier, still-in-flight request's ack applies to), and a
repeat of ERR-0009's N_SLOTS=1 zero-width replication bug in
activation_cache.v itself.
Real, measured results: the full final-benchmark campaign (24/24
workload/config combinations) re-verified bit-exact. D-Stress cycles
fall a further 1.66-2.00x on top of DEC-0015 (~4x combined vs the
original byte-level baseline). But the cache's real Fmax cost is much
steeper than DEC-0015's own: N_SLOTS=2 (the recommended default,
DEC-0014) drops from 133.58 to 87.72 MHz (-34%, margin over 80MHz
shrinks from +67% to +9.7%), and N_SLOTS=4 drops to 65.01 MHz - now
FAILING the 80MHz target it previously passed. Combined real
wall-clock speedup vs the original baseline: N=1 3.86x, N=2 2.45x
(both real net wins); N=4 is a real regression once its own now-failing
Fmax is honestly used, though N=4 was never the recommended
configuration.
N_SLOTS=2 remains the recommended default (DEC-0014 unaffected) with
a thinner but still real Fmax margin. Cache hit-detection pipelining
is flagged as concrete follow-up work if N_SLOTS>2 is ever needed with
the cache active - not attempted this round.
Logged: simulation/synthesis/timing/benchmark/decisions (DEC-0016)/
experiments (EXP-0016)/errors (ERR-0010)/development.log, ROADMAP.md
updated.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_013xXuuRUWZScuo1DeYJxs3v
Implements optimization #1 from the final benchmark campaign's own
recommendation: exploit psram_controller.v's already-implemented
page-mode support (confirmed present by direct inspection) by
fetching multiple bytes per real backend transaction instead of one
at a time.
Root cause addressed: int8_memory_access.v (the byte-level backend
prefetch_engine.v originally sat on) already converts every 8-bit
logical request into a full 16-bit PSRAM word access internally
(mem_addr <= addr >> 1), discarding half of every word it already
paid for. prefetch_engine.v/memory_manager.v now speak
memory_interface.v's own 16-bit word protocol directly, bypassing
int8_memory_access.v entirely - which remains untouched, still frozen
V1 (§1/§34); V2 simply reuses the lower layer of the same frozen
chain instead of the byte-splitting layer on top of it, the same
"reuse what fits" precedent slot_mem_arbiter.v already set.
slot_mem_arbiter.v and neural_multiprocessor.v widened to match
(lb_n/ub_n added, master port wired directly to memory_interface.v).
Real, measured results: M4's own single-job testbench shows 49-56%
fewer cycles (166->84, 446->204, 728->322, all still bit-exact). The
full final-benchmark campaign (24/24 workload/config combinations)
re-verified bit-exact with D-Stress's real wall-clock time (cycles /
real POST-P&R Fmax) improving 2.24-2.37x across every N_SLOTS tested,
against a small real Fmax cost (unchanged at N=1, -6.2% at N=2, -1.2%
at N=4).
tb_neural_multiprocessor.v (M8) and tb_benchmark_suite.v (final
campaign) needed zero changes - both treat neural_multiprocessor.v as
a black box. Only tb_memory_manager.v (M4, rewired to skip
int8_memory_access.v) and tb_dataflow_core.v (M7, behavioral model
widened to word-level) needed updates.
The "real parallel scaling is flat beyond N_SLOTS=2" finding (DEC-0014)
still holds - this optimization made the shared PSRAM port more
efficient per transaction, not multi-ported - so N_SLOTS=2 remains
the recommended default.
Logged: simulation/synthesis/timing/benchmark/decisions (DEC-0015)/
experiments (EXP-0015)/development.log.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_013xXuuRUWZScuo1DeYJxs3v
Post-M10, user-requested final benchmark campaign: 6 realistic
workloads (16-256 independent neurons in a shared-input dense-layer
shape, a random-seeded 2-layer network with real cross-node PSRAM
forwarding, and a 6-node 2-hop dependency diamond) x 4 concurrency
levels (N_SLOTS=1/2/4/8) through the real, full neural_multiprocessor
system (real V1 PSRAM chain, real slot_mem_arbiter). 24/24 runs PASS
bit-exact against a software golden model (11,520 individual neuron/
node checks, zero mismatches).
Three real bugs found and fixed during the campaign itself (ERR-0009):
1. neural_director.v (M5) had a real RTL bug at N_SLOTS=1
($clog2(1)=0 makes a replication expression illegal) - never
caught because M5-M10 only ever tested N_SLOTS=2/4/8. Fixed with
a width-agnostic '0 literal; M5's own testbench re-verified
unaffected.
2/3. Two testbench sizing bugs in tb_benchmark_suite.v itself
(psram_model DEPTH too small for the Large workload's address
range; N_NODES too small for the Stress workload's node-id range,
causing a real deadlock via node-id wraparound colliding with an
already-DISPATCHED node - a real, honest consequence of DEC-0008's
own "no node-slot reclamation" design choice).
Headline finding: real parallel scaling is essentially flat beyond
N_SLOTS=2 - the single shared PSRAM port saturates at ~91%
utilization regardless of slot count, so memory-bound workloads gain
only 1.05-1.06x real speedup from N=1 to N=8. Once real POST-P&R Fmax
degradation is also factored in, N_SLOTS=4 is measurably 21% SLOWER
in real wall-clock time than N_SLOTS=1 for the largest workload
tested. N_SLOTS=2 is recommended as the default (DEC-0014,
superseding DEC-0012's resource-only "N_SLOTS=8 ceiling" framing for
general use).
Full 21-section report (every number classified THEORETICAL/
SIMULATED/POST-P&R MEASURED/DERIVED, per the user's own
methodology requirements): hardware/v2/docs/benchmarks/
final-benchmark.md
Logged: simulation/synthesis/timing/benchmark/decisions (DEC-0014)/
experiments (EXP-0014)/errors (ERR-0009)/development.log,
ROADMAP.md updated.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_013xXuuRUWZScuo1DeYJxs3v
Final milestone of docs/v2-description.md's §33 roadmap, scoped
exactly to its own mandate: optimize only on data already gathered in
M1-M9, across the pipeline/P_IN/processor-count/scheduling/memory
axes - no speculative new features.
Three concrete, data-driven results:
1. N_SLOTS=8 (numero processor axis): real synthesis + nextpnr-ecp5
P&R for dataflow_core at N_SLOTS=8, extending M7's N_SLOTS=2/4
sweep to the real DSP ceiling DEC-0005 predicted. 92.63 MHz
POST-P&R, PASS at 80MHz, DSP 64/72 (88.9%). DEC-0012 recommends
N_SLOTS=8 as the practical ceiling for P_IN=8 on the
LFE5U-45F-8BG381.
2. ACC_WIDTH 24 vs 32 (pipeline axis): a real 6-seed nextpnr-ecp5
placement sweep (reusing already-synthesized netlists, no new
synthesis needed) resolves EXP-0002's single-seed
inconclusiveness. ACC_WIDTH=24 wins on both mean Fmax (+6.2%,
180.71 vs 170.12 MHz) and seed-to-seed variance (~3.4x tighter),
on top of its already-known resource advantage. DEC-0013
recommends ACC_WIDTH=24 as the new default.
3. Stall %/utilization (scheduling/memory axes): testbench-only cycle
counters added to tb_neural_multiprocessor.v (no RTL touched)
close DEC-0011's deferred measurement gap with real data - shared
PSRAM port 81.7% utilized, slot 0 95.2%, slot 1 65.2%, no
conclusive evidence of harmful fixed-priority starvation at this
scale.
The 10-milestone V2 roadmap (docs/v2-description.md §33) is now
complete end-to-end: real Verilator simulation, real Yosys synthesis,
real nextpnr-ecp5 place & route for every milestone, fully logged
(EXP-0001..EXP-0013, DEC-0001..DEC-0013, ERR-0001..ERR-0008) with no
invented results (§30) and V1 kept frozen and untouched throughout
(§1/§34).
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_013xXuuRUWZScuo1DeYJxs3v
Consolidates real, already-measured data from hardware/v1/ (frozen,
pre-certified) and V2's own M1-M8 logs into the §32-mandated
comparison table, on an apples-to-apples basis: both full systems
(V1's spi_neuron_top post_fix_verify vs V2's neural_multiprocessor
N_SLOTS=2), both PARALLEL=8/P_IN=8, both using the real unmodified V1
PSRAM backend.
Headline, all real measurements: V2 full-system Fmax 142.45 MHz
POST-P&R (PASS at 80MHz) vs V1's 68.65 MHz (FAIL at 80MHz); 166 vs 209
real simulated cycles for one neuron's 8-input dot product through the
same real PSRAM chain (2.6x wall-clock speedup); peak MAC/cycle 16
(N_SLOTS=2 concurrent slots, real contention already demonstrated in
EXP-0009) vs V1's 8 (single sequential core); lower LUT/FF despite V2
already including full dependency-graph scheduling that V1 has none
of.
9 of the table's 12 rows carry real sourced numbers; stall %/memory
utilization/processor utilization are reported as NOT MEASURED rather
than approximated (DEC-0011) - a real number needs dedicated
cycle-accounting instrumentation neither system has had built for it
yet, and approximating from partial data would violate §30's "no
invented results" rule. Deferred to M10, which needs exactly this
data to decide what to optimize.
No new RTL this milestone - pure data consolidation, logged as
EXP-0010.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_013xXuuRUWZScuo1DeYJxs3v
neural_multiprocessor.v wraps dataflow_core.v (M7, unmodified) around
the real, unmodified V1 PSRAM backend chain (int8_memory_access ->
memory_interface -> psram_controller), funneling N_SLOTS independent
Memory Backend Interface ports through a new generic N-port arbiter
(slot_mem_arbiter.v) inspired by (not copied from) V1's own
mem_arbiter.v.
Real concurrent-slot simulation immediately surfaced a genuine bug
(ERR-0008): memory_manager/prefetch_engine's byte-level backend
protocol is fire-and-forget (a single-cycle mem_req pulse with no
accept handshake) - correct for M4's direct 1:1 connection, but a
naive arbiter silently drops a pulse arriving while the shared bus is
owned by another slot, hanging that slot forever. Fixed with a
per-port pending-request latch, the same "queue, don't drop" idiom
already used by memory_manager's own pf_pending register (ERR-0006).
Verified (Verilator): 4/4 PASS with 2 slots genuinely contending for
one real PSRAM port (444 cycles). No regression on M4's own
testbench. Real synthesis + nextpnr-ecp5 P&R (no harness needed - real
PSRAM pins keep the top-level at 157 pins): 0 problems, Fmax 142.45
MHz, PASS at 80MHz.
Arbitration policy is fixed lowest-index priority, not fairness-
balanced (DEC-0010) - consistent with every other "simplest correct
policy first" scheduling choice in this roadmap, revisited only if
M9's real measurement shows starvation matters.
Logged: simulation/synthesis/timing/benchmark/decisions (DEC-0010)/
experiments (EXP-0009)/errors (ERR-0008)/development.log, ROADMAP.md
updated.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_013xXuuRUWZScuo1DeYJxs3v
dataflow_core.v integrates dependency_manager (M6) -> neural_director
(M5) -> N_SLOTS x (memory_manager (M4) + neural_processor (M1)) for
the first time. A slot's completion (via neural_director's new
slot_node_id tracking, an additive port) feeds back as a
producer_done event to dependency_manager, waking up any node that
depended on it - closing the dataflow loop without external glue.
Verified end-to-end (Verilator) on a 3-node DAG: two independent
nodes plus a third depending on both, confirmed to dispatch only
after both genuinely complete via real neural_processor computation.
4/4 PASS.
Real synthesis + nextpnr-ecp5 P&R via a synthesis-only timing harness
(bare per-slot backend ports exceed the LFE5U-45F's TRELLIS_IO
budget, same pattern as ERR-0005): N_SLOTS=2 -> 165.15 MHz,
N_SLOTS=4 -> 133.19 MHz, both PASS at 80MHz, 0 synthesis problems.
Scope explicitly deferred to M8 (DEC-0009): M3's BRAM buffers not
wired in yet, per-slot Memory Backend Interface ports not arbitrated
to one shared PSRAM master yet - both need real measured data before
committing to a design, not guessed at here.
Logged: simulation/synthesis/timing/benchmark/decisions (DEC-0009)/
experiments (EXP-0008)/errors (ERR-0007, a Yosys chparam-ordering
build quirk, not an RTL bug)/development.log, ROADMAP.md updated.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_013xXuuRUWZScuo1DeYJxs3v
Implements M6: dependency_manager.v tracks a table of node
descriptors (node_id/state/required_dependencies/resolved_
dependencies/producer_ids -- §10's exact field list), incrementing a
waiting node's resolved count whenever one of its listed producers
completes, transitioning it to READY once resolved==required, and
dispatching ready nodes to the Neural Director (M5) one at a time via
a backpressure-safe valid/ready interface.
Verified with Verilator on a small hand-built DAG: node0/node1 have no
dependencies (dispatch immediately); node2 depends on BOTH node0 AND
node1 ("dipendenze multiple") and stays WAITING until both complete,
confirmed via an explicit negative check after only one resolves;
node3 depends on node0 ALONE, demonstrating a single producer
("node0") satisfying two different consumers' dependencies
("risultati condivisi... piu' consumer") -- node3 fully, node2
partially. 4/4 tests pass.
Scope for this milestone (decisions.log DEC-0008): dependency
COUNTING/readiness only, no direct producer-to-consumer value
forwarding (§11 frames that as a "quando possibile" optimization, not
a correctness requirement -- deferred until real bandwidth
measurements justify it) and no node-slot reclamation after dispatch
(not exercised by any scenario built so far).
Real synthesis: 0 CHECK problems, 763 LUT4/474 FF/0 DSP/0 CCU2C. Real
place&route (module fits the TRELLIS_IO budget as a bare top-level
this time, no harness needed): Fmax 155.30 MHz, PASS at 80MHz.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_013xXuuRUWZScuo1DeYJxs3v
Implements M5: neural_director.v dispatches job descriptors to
whichever of N_SLOTS (memory_manager, neural_processor) pairs is
currently free (first-free scheduling per §9's initial policy), with
a parametric-depth ready-queue FIFO for jobs arriving faster than
slots can absorb them.
Scope for this milestone (see decisions.log DEC-0007): a reduced
4-state FSM (DIR_IDLE/SCAN_READY/ALLOCATE/ERROR) rather than §9's full
8-state baseline -- dependency tracking, the waiting queue, and
wake-up are §10's explicit responsibility (Dependency Manager, M6, not
yet built), and slot-completion detection runs as an always-active
per-slot tracker rather than a dedicated FSM state, for the same
reason DEC-0002 already gave for the Neural Processor's own FSM
(gating concurrent per-unit progress behind one shared state kills
throughput).
Verified with Verilator (N_SLOTS=2, each slot backed by its own
independent behavioral memory rather than sharing V1's real PSRAM --
M4 already proved that path for one slot; this milestone's own concern
is scheduling across multiple slots): 4/4 tests pass -- 3 jobs
submitted to 2 slots (first two dispatch immediately, third correctly
queues until a slot frees), and a deliberate burst that forces the
ready queue to genuinely fill and recover.
Real synthesis: 0 CHECK problems, 382 LUT4/366 FF/4 CCU2C/0 DSP. Real
place&route (via a synthesis-only timing harness, same TRELLIS_IO
pin-budget reason as M2/M4): Fmax 250.50 MHz, PASS at 80MHz.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_013xXuuRUWZScuo1DeYJxs3v
Implements M4: memory_manager.v (arbitration/buffering/forwarding/
latency hiding/double buffering, §12) + prefetch_engine.v
(double-buffered tile fetch, §13), sitting on the REAL, UNMODIFIED V1
PSRAM backend chain (int8_memory_access.v -> memory_interface.v ->
psram_controller.v, per §15's explicit mandate not to touch the
controller).
Verified fully end-to-end with Verilator: real neural_processor (M1)
fed entirely by memory_manager, computing against PSRAM-resident X/W
tiles (double-buffered prefetch across up to 5 tiles) and writing its
result back to PSRAM -- checked via an independent PSRAM read-back,
with poison bytes around the operand regions to catch addressing
errors. 3/3 jobs pass (1/3/5-tile configurations).
Three real RTL bugs found and fixed during integration (full
diagnostic trail in errors.log ERR-0006): prefetch_engine had no
single-in-flight-request discipline, letting a queued request corrupt
the bank bookkeeping of a fetch already running; the fix's own
!pf_busy guard had a one-cycle blind spot (pf_busy lags pf_start by a
clock) that needed an explicit !pf_start term; and a state-based mux
for the shared backend port was off by one cycle, silently dropping
the PSRAM result write entirely.
Real synthesis: 0 CHECK problems, 851 LUT4/789 FF/108 CCU2C/0 DSP
(expected, no multiplication in this module). Real place&route (via a
synthesis-only timing harness, needed for the same TRELLIS_IO pin-
budget reason as M2's array): Fmax 165.86 MHz, PASS at 80MHz.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_013xXuuRUWZScuo1DeYJxs3v
Implements M3: three parametric dual-port buffers for the §12
data-plane (Input/Weight/Result), reusing the proven BRAM-inference
idiom from the frozen hardware/v1/rtl/act_buffer.v (synchronous write,
synchronous REGISTERED read, no reset on the read register -- keeps
Yosys off the LUT-RAM path).
Verified with Verilator: 10/10 tests pass (write-then-read
correctness, extreme INT8 round-tripping, weight_buffer's full 64-bit
tile width round-tripping, undisturbed re-reads).
Real synthesis at two depths per module (6 configs total): 0 CHECK
problems, every configuration correctly infers DP16KD (never
LUT-RAM). Non-obvious real finding: weight_buffer's BRAM cost is
driven by its P_IN*DATA_WIDTH tile width, not its DEPTH -- an 8x depth
reduction (512->64) left DP16KD usage unchanged at 2, while
activation_buffer/result_buffer (byte-wide) scale as naively expected
(2->1). All default-depth configs PASS at 80MHz with large margin
(287-367 MHz) via real nextpnr-ecp5 place&route.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_013xXuuRUWZScuo1DeYJxs3v
micheleandClaude Sonnet 5