Roflin
abc61f3e66
First on-console run: the Identity suite failed with the device ID reading 00 00 00 10 instead of 04 02 02 00. Bit analysis shows that is an EXACT match for the correct stream delayed by 22 bits -- the device answers correctly, just too late for a 32-clock window to catch more than its first set bit. Not corruption, and not a broken link: response latency. At EXI index 5 (~27 MHz) 22 bit-times is ~815 ns, which is about what the CDC chain costs (rx AsyncFIFO capture->exi, register-file decode, tx AsyncFIFO exi->capture, SPI engine) at a 24 MHz exi clock. The design expects the GC to hold the clock idle between the header write and the data read so the register file can prefetch the response; libogc's inter-call overhead alone is not enough at full speed. Adds bba_gap_us (default 16 us, busy-waited with CS asserted since we hold the EXI lock) and a Gap sweep test that reports the minimum clean gap at the current speed -- which measures the latency rather than guessing at it. Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
re-bba-rb — on-console test suite (GameCube)
A .dol you run from Swiss that drives the adapter in Serial Port 1 and
reports pass/fail per test on the TV.
Build
Needs devkitPro's gamecube-dev group (devkitPPC + libogc). The devcontainer
installs it — if DEVKITPPC is unset, rebuild the container, since the
toolchain is added in .devcontainer/Dockerfile.
make # -> gc_bba_test.dol
Copy the .dol to your SD card (SD Gecko / SD2SP2) and launch it from Swiss.
Controls
| Button | |
|---|---|
| D-pad up/down | move |
| A | open a suite / rerun the selected test |
| X | run the selected suite |
| START | run everything |
| Y | clear all results |
| B | back |
What it tests
| Suite | Proves |
|---|---|
| Identity | device enumerates: 04 02 02 00, HIPR, NWAYS |
| Registers | PAR0–5, IMR writable and read back; IR is write-1-clear |
| Reset/control | NCRA RESET self-clears, SR holds |
| EXI integrity | 200 reads with no bit errors; which EXI clock indices work |
| Ethernet | MAC readback, 60-byte ARP transmit (TI), frame receive (RWP/RI) |
| SPRAM/DMA | ring descriptor is well-formed; reads ≥ 0x100 stream until CS |
Things that will bite you
The device ID is a ONE-SHOT. Address 0 returns 04 02 02 00 only until
the first NCRA reset clears id_phase in the gateware; after that it reads
back NCRA. That is correct — it matches the GC's own init order — but it means
the Identity test can only pass once per console power cycle. Run it before
the Reset suite. On a re-run the app reports SKIP with an explanation rather
than a misleading failure.
TI is not proof of transmission. It only means TXFrameDrain handed the
frame to the W5100. A frame can set TI and never reach the wire. The TX test
says so; to confirm the wire, capture on a PC or watch the RX test pick up a
reply.
The RX test needs traffic. It waits ~2 s for any frame. On an isolated
link with nothing talking it will fail legitimately — give the PC an address on
the same subnet (the ARP the TX test sends is aimed at 10.0.0.50, so
sudo ip addr add 10.0.0.50/24 dev <nic> makes the PC answer it and both tests
pass together).
Never over-clock a register read. Asking for N bytes and clocking more
leaves stale prefetched bytes queued and desynchronises the next transaction
— a deterministic every-Nth-read corruption that looks like a signal-integrity
fault. bba_read() clocks exactly len; don't "round up" for convenience.
TXDATA takes one byte per transaction. The register file's effective
address auto-increments per data byte, so a 4-byte write to 0x48 would spill
into 0x49–0x4B. bba_tx_bytes() does it correctly.
Build status
Builds clean (no warnings) with devkitPPC 16.1.0 / GCC 16 in the devcontainer:
gc_bba_test.dol, ~172 KB, entry 0x80003100.
.gitignore excludes the build products — run make to produce the .dol.