Adds FPGA-exclusive access to the onboard W25Q128JV SPI NOR flash for
weights/bias/network persistence, layered as spi_flash_master (raw SPI,
USRMCLK-driven) -> flash_copy_engine (flash<->PSRAM streaming, erase-
before-write, Page Program loop) -> flash_slot_manager (16-slot catalog
with CRC32), exposed via 8 new SPI opcodes (0x40-0x47). Fixes two
pre-existing bugs found during bring-up: a psram_controller.v request
lost during power-up, and a one-cycle-pulse race in the PSRAM arbiter
request handshake. Full simulation + real Yosys/nextpnr-ecp5 synthesis
verification (0 errors, Fmax 66.68MHz) in WORKLOG.md and
docs/FPGA-Neural-Flash-Subsystem-Verification.md.
Also updates docs/pinout to reflect the 56-signal real .lpf (3 new
flash pins) and documents the WRITE_RAM/READ_RAM host backpressure
risk found while testing this subsystem.
Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_013xXuuRUWZScuo1DeYJxs3v
micheleandClaude Sonnet 5
97a21be240