FPGA-Neural/docs/PINOUT.md

FPGA-Neural V3 — Consolidated Pinout Reference

Single-source pinout for the custom PCB (bare XC7A100T-CSG324-2, no dev board). This is a flattened, board-layout-ready extract of docs/PHYSICAL_REALIZATION.md §2 — that document remains the authoritative, narrated source (it explains why each pin was chosen and every real conflict/fix found along the way); this file is the quick reference for schematic capture. Every pin below comes from a real routed design (originally n2_system_ddr3_top_routed.dcp, EXP-0086; the same real pin set — DDR3/SPI/flash/config are all package-level, unaffected by internal core count — was re-confirmed real and unchanged in n8_system_ddr3_top.v's own real routed signoff, EXP-0095/0096, now the current definitive deployment target, see docs/PHYSICAL_REALIZATION.md §3) or the MIG-generated mig_7series_0.xdc — none of it is guessed. Re-generate this file if docs/PHYSICAL_REALIZATION.md §2 ever changes.

Bank summary

Bank	Voltage (VCCO)	Standard	Used for
0	per board config rail	LVCMOS (per UG470)	FPGA configuration control (PROGRAM_B/INIT_B/DONE/mode pins/CFGBVS)
14	2.5V	LVDS_25	clk_ref_p/n only (differential IDELAYCTRL reference clock)
15	3.3V	LVCMOS33	Management SPI (ESP32↔FPGA), sys_rst, data_ready_n
16	3.3V	LVCMOS33	Config flash SPI (FPGA↔flash)
34	1.5V	SSTL15 / DIFF_SSTL15	DDR3 addr/ba/control/ck, sys_clk_p/n
35	1.5V	SSTL15 / DIFF_SSTL15	DDR3 dq/dqs/dm

DDR3 (bank 34/35 — two MT41J128M16JT-125:K chips in parallel, 32-bit channel)

Address/command/control fan out identically to BOTH chips (not duplicated per chip); DQ/DQS/DM are split 16 bits per chip.

Signal	Pin	Signal	Pin	Signal	Pin
ddr3_dq[0]	C5	ddr3_dq[16]	F4	ddr3_addr[0]	U3
ddr3_dq[1]	B7	ddr3_dq[17]	F3	ddr3_addr[1]	U4
ddr3_dq[2]	B6	ddr3_dq[18]	E2	ddr3_addr[2]	V1
ddr3_dq[3]	D8	ddr3_dq[19]	D2	ddr3_addr[3]	U1
ddr3_dq[4]	C7	ddr3_dq[20]	C1	ddr3_addr[4]	L5
ddr3_dq[5]	E6	ddr3_dq[21]	H1	ddr3_addr[5]	L6
ddr3_dq[6]	E5	ddr3_dq[22]	G1	ddr3_addr[6]	L4
ddr3_dq[7]	E7	ddr3_dq[23]	F1	ddr3_addr[7]	K5
ddr3_dq[8]	B4	ddr3_dq[24]	F6	ddr3_addr[8]	M2
ddr3_dq[9]	A4	ddr3_dq[25]	G4	ddr3_addr[9]	M3
ddr3_dq[10]	A3	ddr3_dq[26]	G3	ddr3_addr[10]	L3
ddr3_dq[11]	B3	ddr3_dq[27]	J3	ddr3_addr[11]	K3
ddr3_dq[12]	B2	ddr3_dq[28]	J2	ddr3_addr[12]	M1
ddr3_dq[13]	D5	ddr3_dq[29]	K2	ddr3_addr[13]	L1
ddr3_dq[14]	D4	ddr3_dq[30]	K1	ddr3_ba[0]	V5
ddr3_dq[15]	E3	ddr3_dq[31]	H6	ddr3_ba[1]	V2
ddr3_dm[0]	C6	ddr3_dm[2]	C2	ddr3_ba[2]	U2
ddr3_dm[1]	C4	ddr3_dm[3]	G6	ddr3_cas_n	R3
ddr3_dqs_p[0]	A6 (DIFF)	ddr3_dqs_n[0]	A5 (DIFF)	ddr3_cke[0]	P2
ddr3_dqs_p[1]	B1 (DIFF)	ddr3_dqs_n[1]	A1 (DIFF)	ddr3_cs_n[0]	T5
ddr3_dqs_p[2]	H2 (DIFF)	ddr3_dqs_n[2]	G2 (DIFF)	ddr3_odt[0]	R2
ddr3_dqs_p[3]	J4 (DIFF)	ddr3_dqs_n[3]	H4 (DIFF)	ddr3_ras_n	V4
ddr3_ck_p[0]	N2 (DIFF)	ddr3_ck_n[0]	N1 (DIFF)	ddr3_we_n	T3
ddr3_reset_n	D7 (LVCMOS15)
sys_clk_p	N5 (DIFF_SSTL15)	sys_clk_n	P5 (DIFF_SSTL15)	real, required freq 310.077 MHz

Reference clock (bank 14)

Signal	Pin	Standard	Notes
clk_ref_p	T14	LVDS_25 (2.5V)	required freq 200 MHz, differential
clk_ref_n	T15	LVDS_25 (2.5V)

Bank 14 hosts ONLY clk_ref_p/n — the config-flash bus was moved out of this bank (to bank 16, see below) specifically because it can't share a VCCO with this signal (EXP-0084).

Management SPI — ESP32 ↔ FPGA, FPGA is slave (bank 15, 3.3V)

Signal	Pin	Direction (FPGA side)	Notes
sclk	A15	input
mosi	B16	input
miso	B17	output
cs_n	A16	input
sys_rst	G13	input	tentative pin, not yet a final board decision (§7 of PHYSICAL_REALIZATION.md)
data_ready_n	D14	output	active-low sticky IRQ (EXP-0085); tentative pin, same caveat as sys_rst

Config flash SPI — FPGA ↔ Winbond W25Q32JVSSIQ, FPGA is master (bank 16, 3.3V)

Signal	Pin	Direction (FPGA side)	Notes
flash_mosi	D9	output	connects to flash DI
flash_miso	D10	input	connects to flash DO
flash_cs_n	C9	output	connects to flash /CS
(CCLK)	E9	output	not a top-level RTL port — internally driven via STARTUPE2; wire the flash's own CLK pin directly to package pin E9

No direct ESP32↔flash connection exists by design — the ESP32 can only reach the flash by relaying bytes through the FPGA over the management SPI bus (FLASH_XFER opcode 0x40, see §5/§6 of PHYSICAL_REALIZATION.md).

FPGA configuration control (bank 0, fixed by the device, not negotiable)

Signal	Pin	Purpose
PROGRAM_B	P9	pulse low to force reconfiguration from flash
INIT_B	P7	low during config; re-asserting can indicate a config error
DONE	P10	goes high once configuration succeeds — good status-LED candidate
M0	P12	mode select — tie per the Master SPI boot setting below
M1	P13	mode select
M2	P11	mode select
CFGBVS	P8	tie to match bank 0's own VCCO logic level (see UG470)

Master SPI boot mode pins: M[2:0] = 001 — tie via pull-up/pull-down resistors on the board (static, not driven dynamically).

JTAG (bank 0, always available)

Signal	Pin
TCK	E10
TDI	E11
TMS	E12
TDO	E13

Intended to be driven by the ESP32 bit-banging the TAP state machine (factory programming, recovery, development) — see §5.1 of docs/ARCHITECTURE_ANALYSIS.md; that firmware doesn't exist yet.

Reserved / do-not-use (bank 14)

L16 (EMCCLK), R16 (RDWR_B), V15 (CSI_B) — config-mode-reserved, PROHIBITed in the project XDC (via get_sites -of_objects, not directly on the package_pin objects — a real Vivado property gotcha, see CLAUDE.md). Kept clear for any future Quad-SPI/BPI expansion; not used by this design's own Master-SPI-only configuration scheme.

Open items (not yet finalized — do not treat as final for PCB layout)

• sys_rst (G13) and data_ready_n (D14) are real, verified-free pins chosen only to unblock P&R — not yet a final board decision pending the rest of the layout (reset circuit, status LEDs).
• Bank 15/16 VCCO is assumed 3.3V in this pinout — confirm against the real board power plan before finalizing.
• sys_clk_p/n and clk_ref_p/n oscillator part selection (real, in-stock candidates) is tracked in docs/BOM.md.