Enable in-container USB flashing + flash-re-bba-rb skill; find U7 EEPROM undersized
Devcontainer now grants libusb access to the FT2232H so iceprog (bitstream) and pyftdi (FT2232H EEPROM) run inside the container: - devcontainer.json: --privileged + /dev/bus/usb bind mount - Dockerfile: sudo (NOPASSWD for vscode; USB nodes are root-owned), libusb-1.0-0, libftdi1-2, pyftdi Add the flash-re-bba-rb skill documenting the procedure (bitstream via best swept seed, optional EEPROM string, troubleshooting, guardrails) and flash_ftdi_eeprom.py (pyftdi, backup-first, dry-run default) + ftdi_eeprom.conf value spec. Bring-up on the repaired V1 unit: bitstream flash VERIFY OK (iceprog build/seed4/top.bin, capture 58.36 MHz). EEPROM product string CANNOT be programmed on V1 — U7 is a 93LC46B (128 B), too small for the FT2232H, which needs a 93LC56B (256 B); the 128 B chip mirrors and the config write fails verify. This overturns the old REVIEW note "93LC46B = correct for FT2232H" (that only checked ORG, not size). Board still works blank -> ROM defaults; iceprog + UART unaffected. Documented in REVIEW.md + TODO.md (swap U7->93LC56B for V2); flash_ftdi_eeprom.py detects the mirroring and refuses the write. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
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@@ -74,8 +74,23 @@ datasheet extraction, WebSearch/WebFetch for parts and reference designs.
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change); TEST→GND, AGND→GND.
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- **EEPROM 93LC46B (U7)**: interface **was wrong** (DO+DI both direct to
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EEDATA) → fixed per DS Table 3.4: EE_DO net, R30 2.2k (C25879) to EE_DATA,
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R31 10k (C25744) pull-up to 3V3, DI direct. 93LC46B = fixed 16-bit org =
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correct for FT2232H. Verified in netlist.
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R31 10k (C25744) pull-up to 3V3, DI direct. 93LC46B = fixed 16-bit org (that
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part of the earlier verdict stands). **Interface wiring verified in netlist.**
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- **⚠️ U7 PART IS UNDERSIZED — found at bring-up 2026-08-22 (overturns the old
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"93LC46B = correct for FT2232H" note, which only checked ORG, not size).**
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The 93LC46B is **1 Kbit = 128 bytes**; the FT2232H addresses a **256-byte**
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EEPROM (`max_eeprom_size=256`) and its config does not fit in 128 B. FTDI
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specs a **93LC56B (256 B)** or 93LC66B for the H-series — the 93LC46 is for the
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FT232R / FT2232**D**. Empirical evidence (pyftdi on the repaired V1 unit): the
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128-byte chip mirrors into the upper half (`has_mirroring=True`); a config
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write mirror-clobbers word 0x80→0x00 and **fails verify at word 0x02**; and
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`set_property` indexes past byte 128. **Consequence:** the "re-BBA-rb" product
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string CANNOT be stored on V1. **Not a functional defect** — with U7 left
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blank the FT2232H uses ROM defaults ("Dual RS232-HS", 0403:6010), and iceprog
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(bitstream flash — verified OK on this unit) + the channel-B UART work
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normally. **Fix for a future rev:** fit a 93LC56B at U7 (same SOIC-8, fixed
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16-bit org, pin-compatible). Tooling: `hardware/re-bba-rb/flash_ftdi_eeprom.py`
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detects the mirroring and refuses the write; `--erase` blanks U7.
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- **EE_CS pull-down (R43, 10 kΩ) — ADDED 2026-07-31.** FT2232H DS Table 3.4
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states EECS/EECLK/EEDATA are all **"Tri-State during device reset"**, so CS
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floats while the FT2232H is in reset. The Microchip 93LC46B DS is explicit:
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@@ -102,7 +117,10 @@ datasheet extraction, WebSearch/WebFetch for parts and reference designs.
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CDONE=ADBUS6, CRESET=ADBUS7 (verified against iceprog.c; old ADBUS3/ACBUS0/
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ACBUS1 now NC). R11/R12 10k pull-ups on CRESET/CDONE intact.
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- **EEPROM contents decision**: ship blank (default 0403:6010 = what iceprog
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opens). Documented in TODO.
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opens). Documented in TODO. **Update 2026-08-22:** on V1 this is now *forced*
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blank, not just a choice — U7 (93LC46B) is too small to hold an FT2232H config
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(see the U7-undersized note above), so the product string can't be programmed
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until a 93LC56B is fitted. Blank is the correct, working state.
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## 4. FPGA sheet (`Fpga.kicad_sch`) — FULLY REVIEWED, PASS
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@@ -358,6 +358,15 @@ Major work this session:
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## Minor / BOM
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- [ ] **U7 EEPROM undersized — swap 93LC46B → 93LC56B for V2 (found at bring-up
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2026-08-22).** The 93LC46B is 128 B; the FT2232H needs ≥256 B (93LC56B /
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93LC66B) to hold its config, so the "re-BBA-rb" USB product string can't be
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programmed on V1 (write mirrors + fails verify — see REVIEW.md "U7 PART IS
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UNDERSIZED"). **Not a functional blocker:** V1 ships with U7 blank → FT2232H
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ROM defaults ("Dual RS232-HS", 0403:6010); iceprog bitstream flash (VERIFY
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OK on the repaired unit) and the channel-B UART are unaffected. 93LC56B is
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the same SOIC-8 / fixed-16-bit-org, pin-compatible drop-in. Pick a JLC part
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(e.g. 93LC56BT-I/SN) when respinning.
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- [x] RSET_BG 12.4 k — ACCEPTED 2026-07-18 (closed, no change): datasheet
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says 12.3 kΩ, but that is an E192 value with no JLC Basic part —
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WIZnet's own reference synthesizes it as 12 k + 300 Ω. The 0.8 %
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@@ -0,0 +1,183 @@
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#!/usr/bin/env python3
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"""Program the re-bba-rb FT2232H EEPROM so the unit enumerates as "re-BBA-rb".
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Uses pyftdi (libusb) — the in-container tool, since debian's libftdi1-2 ships
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only the runtime lib, not the `ftdi_eeprom` binary. The intended descriptor
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values mirror hardware/re-bba-rb/ftdi_eeprom.conf.
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SAFE BY DESIGN:
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* Keeps the stock VID/PID 0403:6010 and the dual-channel config, so iceprog
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(MPSSE on channel A) and the channel-B UART keep working unchanged — only
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the descriptor STRINGS change.
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* DRY-RUN BY DEFAULT: prints the diff and writes a raw backup, but does NOT
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touch the EEPROM unless you pass --commit.
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* Always dumps the current EEPROM to a backup file first.
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Usage (inside the rebuilt devcontainer, FT2232H usbipd-attached):
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sudo /opt/venv/bin/python hardware/re-bba-rb/flash_ftdi_eeprom.py # dry-run + backup
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sudo /opt/venv/bin/python hardware/re-bba-rb/flash_ftdi_eeprom.py --commit # write strings
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sudo /opt/venv/bin/python hardware/re-bba-rb/flash_ftdi_eeprom.py --erase --commit # blank U7
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⚠️ re-bba-rb V1 HARDWARE LIMITATION: U7 is a 93LC46B (128-byte / 1 Kbit) EEPROM,
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which is TOO SMALL for the FT2232H — the H-series needs a 93LC56B (256 B) or
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93LC66B (the 93LC46 is for the FT232R / FT2232D). The FT2232H config mirrors in
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the 128-byte chip and the string write fails verify, so the "re-BBA-rb" product
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string CANNOT be programmed on V1. This script therefore REFUSES the write when
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it detects mirroring (use --force to override, --erase to blank U7). The board
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is fully functional without it: it enumerates on ROM defaults ("Dual RS232-HS",
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0403:6010) and iceprog + the channel-B UART work normally. Fix in a future rev
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by fitting a 93LC56B at U7.
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Flash the FPGA bitstream FIRST and confirm iceprog works — the string is purely
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cosmetic. Do NOT rely on reset_device(): it re-enumerates the FT2232H and drops
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the usbipd attachment on WSL2 — re-attach with usbipd instead.
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"""
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import argparse
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import sys
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from pathlib import Path
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VID = 0x0403
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PID = 0x6010
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URL = f"ftdi://0x{VID:04x}:0x{PID:04x}/1"
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MANUFACTURER = "hashru"
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PRODUCT = "re-BBA-rb"
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SERIAL = "RBBARB001"
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BACKUP = Path(__file__).with_name("eeprom-backup.bin")
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def main() -> int:
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ap = argparse.ArgumentParser(description=__doc__)
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ap.add_argument("--commit", action="store_true",
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help="actually write the EEPROM (default: dry-run only)")
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ap.add_argument("--erase", action="store_true",
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help="blank U7 to 0xFF (FT2232H falls back to ROM defaults)")
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ap.add_argument("--force", action="store_true",
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help="attempt the string write even if U7 reports mirroring "
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"(undersized 93LC46B) — will likely fail/corrupt")
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ap.add_argument("--url", default=URL, help=f"pyftdi device URL (default {URL})")
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args = ap.parse_args()
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try:
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from pyftdi.eeprom import FtdiEeprom
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except ImportError:
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print("pyftdi not installed. In the devcontainer it is preinstalled; "
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"otherwise: pip install pyftdi", file=sys.stderr)
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return 2
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eeprom = FtdiEeprom()
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try:
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eeprom.open(args.url)
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except Exception as exc: # noqa: BLE001 - surface the real libusb error
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print(f"Could not open {args.url}: {exc}", file=sys.stderr)
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print("Is the FT2232H usbipd-attached, and are you running under sudo?",
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file=sys.stderr)
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return 1
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# 1) Backup the current EEPROM image before any change.
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try:
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BACKUP.write_bytes(bytes(eeprom.data))
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print(f"Backed up current EEPROM ({len(eeprom.data)} bytes) -> {BACKUP}")
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except Exception as exc: # noqa: BLE001
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print(f"WARNING: could not write backup ({exc}); aborting.", file=sys.stderr)
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eeprom.close()
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return 1
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# --- Erase mode: blank U7 back to 0xFF (FT2232H then uses ROM defaults). ---
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if args.erase:
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return _erase(eeprom, args.commit)
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# ------------------------------------------------------------------
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# HARDWARE NOTE — U7 on re-bba-rb V1 is a 93LC46B (1 Kbit = 128 bytes).
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# The FT2232H addresses a 256-byte EEPROM and its config does NOT fit in
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# 128 bytes: pyftdi sees the 128-byte chip mirror into the upper half
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# (has_mirroring=True), the config write mirror-clobbers word 0x80->0x00,
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# and verify fails. FTDI specs a 93LC56B (256 B) / 93LC66B for the H-series
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# (the 93LC46 is for the FT232R / FT2232D). So the product string CANNOT be
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# stored on V1 — the board still works fine on ROM defaults ("Dual RS232-HS",
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# 0403:6010; iceprog + the UART are unaffected). Refuse rather than
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# half-write (which corrupts U7 and needs an --erase recovery).
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# ------------------------------------------------------------------
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if eeprom.has_mirroring and not args.force:
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print("\nREFUSING: U7 reports EEPROM mirroring — it is a 128-byte chip "
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"(93LC46B), too small for the FT2232H's 256-byte config.\n"
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"The 're-BBA-rb' product string cannot be stored on this board "
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"(see the header comment / REVIEW.md). The board works fine on ROM "
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"defaults. Use --erase to (re)blank U7; --force to attempt anyway.",
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file=sys.stderr)
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eeprom.close()
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return 3
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# Stage a COMPLETE FT2232H default config, then overlay our strings.
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print(f"\nEEPROM currently blank: {eeprom.is_empty} — staging FT2232H defaults.")
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eeprom.initialize()
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cfg = eeprom._config # decoded config dict (no public accessor in pyftdi 0.57)
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print("\nCurrent (staged-base) descriptors:")
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print(f" vendor_id = 0x{cfg.get('vendor_id', 0):04x}")
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print(f" product_id = 0x{cfg.get('product_id', 0):04x}")
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# Stage the new strings (VID/PID/channel config untouched).
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eeprom.set_manufacturer_name(MANUFACTURER)
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eeprom.set_product_name(PRODUCT)
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eeprom.set_serial_number(SERIAL)
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print("\nStaged descriptors:")
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print(f" manufacturer = {MANUFACTURER!r}")
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print(f" product = {PRODUCT!r}")
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print(f" serial = {SERIAL!r}")
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if not args.commit:
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print("\nDRY-RUN — nothing written. Re-run with --commit to program.")
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eeprom.close()
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return 0
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try:
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eeprom.commit(dry_run=False)
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except Exception as exc: # noqa: BLE001
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print(f"\nWRITE FAILED ({exc}). U7 may be partially written — run with "
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"--erase to blank it back to ROM-default fallback.", file=sys.stderr)
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eeprom.close()
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return 1
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eeprom.close()
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# NOTE: do NOT call reset_device() — it re-enumerates the FT2232H, which
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# drops the usbipd attachment on WSL2. Re-plug / re-attach manually instead.
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print("\nEEPROM written. Re-attach USB (usbipd) so the host shows 're-BBA-rb'.")
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return 0
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def _erase(eeprom, commit: bool) -> int:
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"""Blank U7 to 0xFF so the FT2232H falls back to ROM defaults.
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On the mirrored 128-byte chip pyftdi's 256-byte verify trips even though the
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0xFF writes land, so we loop and check the actual content instead of trusting
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commit()'s verify.
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"""
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if not commit:
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print("\n--erase DRY-RUN: would write 0xFF over U7. Add --commit to do it.")
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eeprom.close()
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return 0
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for attempt in range(5):
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data = bytes(eeprom.data)
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nonff = sum(1 for b in data if b != 0xFF)
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print(f"erase attempt {attempt}: non-0xFF bytes = {nonff}")
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if nonff == 0:
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print("U7 is fully blank — FT2232H will use ROM defaults.")
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eeprom.close()
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return 0
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eeprom.erase(0xFF)
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try:
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eeprom.commit(dry_run=False)
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except Exception as exc: # noqa: BLE001 - mirrored-chip verify trips; writes still land
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print(f" (commit verify raised, expected on mirrored chip: {exc})")
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# Re-read fresh next loop without reset_device() (which drops usbip).
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eeprom.sync()
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print("Could not fully blank U7 after retries — re-run --erase after re-attach.",
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file=sys.stderr)
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eeprom.close()
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return 1
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if __name__ == "__main__":
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raise SystemExit(main())
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@@ -0,0 +1,45 @@
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# FT2232H EEPROM config for the re-bba-rb board (libftdi `ftdi_eeprom`).
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#
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# NOTE: the devcontainer does NOT ship the `ftdi_eeprom` binary (debian's
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# libftdi1-2 is the runtime lib only). Inside the container program the EEPROM
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# with the pyftdi script instead — it applies the SAME values as this file:
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# sudo /opt/venv/bin/python hardware/re-bba-rb/flash_ftdi_eeprom.py --commit
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# This .conf remains the value spec, and works as-is with `ftdi_eeprom` on a host
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# that has the libftdi tools, or as a reference when using FT_PROG on Windows.
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#
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# Purpose: give the on-board FT2232H a product string so the unit shows up as
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# "re-BBA-rb" instead of the generic "Dual RS232-HS".
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#
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# SAFE BY DESIGN — this KEEPS the stock VID/PID (0403:6010) and the default
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# dual-channel config, so `iceprog` (MPSSE on interface A) and the channel-B
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# UART keep working exactly as before. Only the descriptor strings change.
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#
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# ⚠️ Before writing: back up whatever is there (it should be blank/default):
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# ftdi_eeprom --device i:0x0403:0x6010 --read-eeprom --to-file eeprom-backup.bin
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# Then flash the bitstream FIRST and confirm iceprog works; program this
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# EEPROM only after that's proven (the string is cosmetic).
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#
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# Program with:
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# ftdi_eeprom --device i:0x0403:0x6010 --flash-eeprom ftdi_eeprom.conf
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# (re-plug the USB afterwards so the host re-reads the descriptors.)
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vendor_id=0x0403 # KEEP 0403 — iceprog/D2XX look for this
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product_id=0x6010 # KEEP 6010 — FT2232H default; iceprog looks for this
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max_power=500 # mA; board draws well under this over USB
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manufacturer=hashru # <- your name/org; free text
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product=re-BBA-rb # <- this is what makes it show as "re-BBA-rb"
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use_serial=true
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serial=RBBARB001 # <- optional; bump per unit if you want unique serials
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# Bus-powered while flashing over USB (GC not attached). If you ever program
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# it while powered from SP1 only, this is still fine — it's a hint to the host.
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self_powered=false
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remote_wakeup=false
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# Leave the two channels at their FT2232H defaults (UART/serial). MPSSE (used
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# by iceprog) is a runtime mode on interface A and works regardless, so there
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# is no need to set cha_type/chb_type here.
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filename=re-bba-rb-eeprom.bin # ftdi_eeprom writes the built image here too
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Reference in New Issue
Block a user