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Both directions proven on hardware: 60-byte ARP out, DHCP frame in

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TX: the TWD fix lands a full 60-byte ARP on the wire, byte-for-byte correct
(previously truncated at 16).  TI sets.

RX: a real 342-byte DHCP broadcast from the PC was received in MACRAW mode,
assembled into the SPRAM ring and DMA-read back over EXI.  The descriptor
length 0x015A cross-checks exactly against the frame's own IP total-length
field plus the ethernet header, so the assembler's length is confirmed, not
merely plausible.

Also replaces the full-path probe's 'is 08 and 06 somewhere in the buffer'
guess with a real descriptor decode -- it called a DHCP frame an ARP reply.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
This commit is contained in:
Dennis Brentjes
2026-09-30 18:59:26 +00:00
parent d156df1dda
commit 6621ce9d0d
2 changed files with 25 additions and 2 deletions
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CLAUDE.md
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@@ -277,6 +277,22 @@ Pi over J4 with the board on 12 V — device ID `04 02 02 00`, NCRA reset
self-clearing, PAR0–5, MAR0–7, ANALOG, NWAYC, IMR `0x86` readback, NCRA SR,
and NWAYS `0x17`. See `hardware/re-bba-rb/exi_fullpath_rpi.py`.
✅ **BOTH DIRECTIONS PROVEN ON HARDWARE 2026-09-30 — the BBA data path works.**
*GC → wire* (after the TWD fix below): a full **60-byte ARP request**, captured
on the PC byte-for-byte correct — broadcast dst, `00:09:bf:00:00:01` source,
ethertype 0806, sender 10.0.0.99, target 10.0.0.50, padded to 60. TI sets.
*wire → GC*: a real **342-byte DHCP broadcast** from the PC was received by the
W5100 in MACRAW mode, assembled into the SPRAM ring by `RXFrameAssembler`, and
DMA-read back over EXI from 0x100. RI set. The ring descriptor read
`00 00 01 5A` = 346 = 342 + 4, and the frame's own IP total-length field (328)
+ 14 bytes of ethernet header = 342 — so the assembler's length is
independently confirmed correct, not just plausible.
Together: EXI ↔ BBARegisterFile ↔ {tx_bytes→TXFrameDrain, SPRAM ring} ↔
W5100ParallelMaster ↔ PHY, in both directions, on silicon.
✅ **GC→wire TX REACHES THE WIRE — the full path is proven.** A frame written
over EXI to TXDATA and triggered via the NCRA ST bits was captured on a PC:
`ff ff ff ff ff ff | 00 09 bf 00 00 01 | 08 06 | 00 01` — broadcast dst, our