fix: chunk SLIP frame writes for USB CDC compatibility#16
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jgangemi wants to merge 1 commit intotinygo-org:mainfrom
Open
fix: chunk SLIP frame writes for USB CDC compatibility#16jgangemi wants to merge 1 commit intotinygo-org:mainfrom
jgangemi wants to merge 1 commit intotinygo-org:mainfrom
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The ROM bootloader's CDC implementation on chips like ESP32-S3 drops packets when large SLIP frames (1KB+) are written in a single call. Write in 64-byte chunks to match the USB CDC endpoint max packet size. Tested on ESP32-S3 (T-Dongle S3) — two successful 1MB firmware flashes with zero timeouts (previously failed consistently around 45-300KB). Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
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Problem
The ROM bootloader's USB CDC implementation on chips like the ESP32-S3 drops packets when large SLIP frames (1KB+) are written in a single call. This causes firmware flashes to timeout or fail partway through the upload process.
Solution
Modified
sendCommand()inpkg/espflasher/protocol.goto write SLIP frames in 64-byte chunks, matching the USB CDC endpoint max packet size. This ensures the ROM bootloader's CDC driver can handle the data reliably.Testing
Tested on ESP32-S3 (T-Dongle S3):
Note
This fix applies only to the ROM bootloader path. The stub loader path is unaffected.
Co-Authored-By: Claude Opus 4.6 noreply@anthropic.com