Files
FPGA-Neural/hardware/v2/logs
micheleandClaude Sonnet 5 9dead54ebf feat: real 32-bit DDR3 channel widening - functionally complete, timing NOT yet closed (EXP-0084)
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
2026-09-20 16:28:44 +02:00
..

Formato dei log V2

Regola non negoziabile (docs/v2-description.md §25-29): ogni attività significativa (modifica, simulazione, sintesi, benchmark, decisione, errore) deve essere registrata. Nessun log viene mai sovrascritto o troncato — solo append. Nessun ID esperimento (EXP-XXXX) o decisione (DEC-XXXX) viene mai riutilizzato, anche se il risultato è un FAIL.

File

  • development.log — log principale di sviluppo, un'entry per ogni sessione di lavoro/milestone (creazione file, refactor, avanzamento roadmap).
  • architecture.log — decisioni e note di architettura a grana fine (non scelte finali — quelle vanno in decisions.log — ma esplorazioni, alternative considerate, vincoli scoperti).
  • simulation.log — ogni run di simulazione (Icarus/Verilator): test, vettori, cicli, PASS/FAIL, confronto bit-exact con V1, stall/memory-wait.
  • synthesis.log — ogni run Yosys: LUT/FF/DSP/BRAM, warning, problemi CHECK.
  • timing.log — ogni run nextpnr-ecp5: Fmax, percorso critico, WNS/TNS se disponibili. Fmax "ufficiale" di una configurazione = solo da qui, mai da simulazione o stima.
  • benchmark.log — tabelle di confronto per configurazione (Fmax, MAC/cycle, cycles/neuron, utilization, ecc.), sempre con etichetta THEORETICAL/SIMULATED/SYNTHESIZED/POST-P&R.
  • decisions.log — decisioni architetturali importanti, formato DEC-XXXX (vedi docs/v2-description.md §27).
  • experiments.log — registro principale, un EXP-XXXX per ogni esperimento end-to-end (config → sim/synth/timing → risultato), rimanda a reports/experiments/EXP-XXXX/.
  • errors.log — errori/bug/regressioni incontrati durante lo sviluppo V2 stesso (non i bug V1, già chiusi in hardware/v1/docs/validation/bugs.md).

Campi minimi per entry (§26)

timestamp, experiment_id (se applicabile), git_commit, session/agent,
module, configuration, action, reason, command, result, errors, decision,
next_action

Per synthesis/timing aggiungere: LUT, FF, DSP, BRAM, Fmax, critical path, WNS/TNS. Per simulazione: test, vectors, cycles, PASS/FAIL, bit-exact result, stall cycles, memory wait, utilization.