ESP32-C3 `no-std` UART Logging Issue

[apollolabsdev]

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Using ESP32-C3 and no-std, attempting to log to the console using UART0 alongside println does not work. The code pauses without any output printed.

This is a follow-up to the closed issue: esp-rs/esp-hal#1531 .

For the non-Rust ESP32-C3 devkits, both UART and esp_println share the same lines, however, this behavior does not seem to reflect on Wokwi. I was not able to verify on hardware myself with a different devkit as I only have access to a Rust board.

[urish]

Thanks for reporting! If I understand correctly, the prints go to the Serial JTAG UART?

[apollolabsdev]

Correct. For the ESP32-C3s. Though the devkitM utilizes an external USB-UART bridge (schematic).

[urish]

Update: we now have support for logging to the serial JTAG UART. It can be enabled by adding an attr to diagram.json:

https://docs.wokwi.com/guides/esp32/#usb-cdc-serial-over-usb-support