ESP32 Forum

Hello,
I have a custom board with footprints broken out for VCC, GND, TX, RX, along with USB-JTAG IO12 and IO13.

The setup:
* ESP32-C6-M1 dev board (https://espressif-docs.readthedocs-host ... matics.pdf)
* No power provided to dev board ESP32 module (there is a header you can just disconnect)
* Route IOs from this board to the custom board pads (either JTAG or UART)

The problem:
In UART mode, serial communication is working correctly, I can see the output in the console. The issue is that IO9, despite being grounded, rarely boots in DOWNLOAD mode. Sometimes does, mostly doesn't. Unfortunately, breadboard wires are used for the connection, so there's the possibility that the ground on IO9 is not great, but remember TX/RX/VCC/GND always work. Besides, reading IO9 in software reports 0.

In USB JTAG mode using IO12 and IO13 as a simple jump from the dev board to the custom board (there are reasons!), the custom board is sometimes recognized as a USB device, mostly not. It should be really straightforward, I have done my best to ensure a robust connection.

If anyone has suggestions or theories, that would be appreciated.

If possible, use debugging tools like oscilloscopes or logic analyzers to monitor the signals during the boot process. This can help identify any anomalies or timing issues. Since it's a custom board, you must check for short circuits or broken traces. You can check with a multimeter. You can make a PCB tester like this too: https://www.pcbway.com/project/sharepro ... 226d2.html

Thanks-

Turns out to have been a very mundane issue. The part making the connection to the serial / jtag pads on the board, while appearing OK, was not making good enough a connection.