Description
SOTACAT modules based on the Seeed Studio ESP32C3 MCU causes KX2/KX3 radios to lock up if the SOTACAT is connected to the radio when booting.
It appears that the ESP32C3 is emitting a bunch of boot messages into the KX via the UART and that these random characters get the KX into a locked state that can only be fixed by a KX power cycle.
- If the ESP32C3 is booted first, and then attached to the KX radio there is no problem.
- The problem does not seem to happen on Wemos LOLIN32 Lite based ESP32 boards
- I tried using the PlatformIO / Espressif "Run MenuConfig" tool and tried changing "Bootloader Config -> Bootloader Log verbosity -> None" and other variations and this did not solve the issue.
- There are two active UARTs in SOTACAT: the one connected to the USB connector which are sent to the host computer when debugging, and the UART connected to the KX radio. I expect boot messages to go to the USB UART and not the KX UART, especially since the KX UART is not configured in the Firmware to send anything until after booting. So I'm confused what is happening.
If turning off bootloader messages doesn't solve the issue, then I am confused why the KX is locked up. We may want to attach a serial port sniffer between the radio and the KX.