allow to switch between USB_CDC and UART for ESP32C3 boards

[MaBecker]

'DEFINES+=-DUSB_CDC', # Disable this line to use serial interface

Tested with both ESP32C3 boards. Please let me know if this is ok or you want me to change anything.

[gfwilliams]

Looks great - thanks!

[SimonGAndrews]

hi @MaBecker , I'm curious how the uart knows what pins to use for tx and rx. I can see in jshardwareUart.c , in the case where serial device is EVSERIAL1, line 65 that inituart() is being called with tx and rx gpio set to -1. Is that the way the tx and rx are disabled ? That may have been the desired state when using the usb.

(the screen shot shows this call and the inituart() function on line 34. )

[gfwilliams]

Espruino tries to search for supported UART pins if none are specified, so it might come from: https://github.com/espruino/Espruino/blob/master/boards/ESP32C3_IDF4.py#L162-L163