The APU boards have a COM2 port on them, which I believe is 3V3. I was wondering of the serial console messages are also sent to that port along with the main DB9 port ?
I was wondering if one can use a ESP-01 on this port for remote serial debug.
I have successfully added a ESP-01 on the AP (Comfast). I have flashed ESPTerm on the ESP-01, can can do serial debug on that board.
Any second port should be available for applications as for example /dev/ttyS1. The kernel will have opened only the first port for logs and console access.
Since a TTL style port idles with the TX line high, you can measure the voltage at the TX pin to determine the logic level needed.
