SOLDERED 333020 / MCP2518 CAN DIAGNOSTIC EVIDENCE
Prepared 2026-09-19; tests performed 2026-09-18.

QUESTION FOR SUPPORT
SPI and internal loopback work, but external CAN reception/transmission fails.
Please advise accessible supply/standby test points or additional diagnostics.
The evidence localizes the problem toward the external CAN path; it does NOT
prove a specific IC is defective. No oscilloscope/logic analyzer is available.

SETUP AND USER-REPORTED MEASUREMENTS
LilyGo T-2CAN ESP32-S3, external Soldered 333020 board.
SCK38, MISO37, MOSI42, CS41, INT39; shared logic GND.
External regulated 5 V supply; LilyGo 5 V wire to module disconnected.
VCC/GND=5.00 V; idle CANH/GND=2.55 V, CANL/GND=2.54 V.
Bench isolated from inverter and batteries. Two 120-ohm terminations,
60 ohms measured H/L unpowered. Terminal clamps also bypassed by soldering
wires to their PCB pads. Two pinched logic wires replaced; full power cycles.
Failure initially followed PSU change/restart. Original PSU restored without
recovery. This timing does not prove the PSU caused damage.

PRIMARY LOGS (corrected nominal timing)
canb-diag3-b2s.log / canb-diag3-s2b.log:
  Native LilyGo CANB versus Soldered, both directions fail; one queued frame
  then stop on error. Soldered TX: TREC=00108800, BDIAG0=00001100,
  BDIAG1=00010000, TXSTA=00000033, peer receives no matching frame.
canable-diag5-rx-powercycle-{usb,pi}.log:
  Independent CANable B sends, Soldered receives zero; stops after first
  missing response. SocketCAN local TX echo is NOT proof of physical reception.
canable-diag5-tx-final-{usb,pi}.log:
  Soldered sends, CANable receives no new frame. Same error registers as DIAG3.
  Compare counter deltas, not pre-existing absolute peer counters.
  These were intended bounded multi-frame tests but stopped at first failure;
  do not interpret them as 20 seconds of successful transmission attempts.
extloop-diag4-r1-loop20.log:
  External-loopback mode: 20 internally returned frames, independent CANB
  observer sees zero. Controller internal return is NOT transceiver validation.
internal-diag6-usb.log:
  Internal-only mode: 20/20 exact frames, 20/20 INT transitions, 42 checks PASS.
internal-diag7-usb.log:
  Firmware summary PASS: 3000 matched frames, 3000 INT checks, 3022 health
  checks over 303061 ms. USB log has a gap after frame 1616; only 1616 complete
  RX lines retained, then final fragment/status/PASS. Final counters are from
  firmware, not an independent audit of all 3000 frames. Gap cause unknown.
lilygo-selftest-usb.log:
  30 s CPU/internal RAM test: 128 KiB, 1936 memory passes, 1936000 known-answer
  CRC calculations on core 1, heap checks pass. No unexpected reboot observed.
  Not a whole-board test; PSRAM disabled due to GPIO overlap, other core and
  external transceivers not tested. Reset reason 11 = host-initiated USB reset.

TIMING AND INTERPRETATION
Bench library initially had nominal timing fields missing minus-one encoding.
DIAG3 and later use corrected NBTCFG=003e0f0f, 500 kbit/s assuming 40 MHz.
OSC=00000460. Actual physical clock frequency has NOT been measured.
Original production Battery Emulator uses a different CAN library; this bench
bug does not by itself explain the original incident.
BDIAG1 bit16 is NBIT0ERR; low 16 bits count successful frames and are not errors.
The legacy_logs folder contains earlier/aborted/pre-correction runs for history
ONLY. Do not use their failures as independent corrected-bitrate evidence.
Zero CAN error counts without received traffic do not establish a healthy bus.

CONTENTS AND PRIVACY
Selected diagnostic logs plus diagnostic application sources and one corrected
Soldered library copy are included. Original logs retained locally; attachment
copies redact local usernames, IP/MAC addresses and adapter serial identifiers.
No flash dumps, NVS, production firmware, passwords or photos are included.
Flash progress logs omitted because they do not diagnose CAN function.
SHA256SUMS covers the attachment contents (after redaction).
Sources are provided for review, NOT as instructions to flash a live installation.
