Attaching a USB to Serial Adapter

  1. Solder in the UART debug header, using one that matches the specifications of the UART debug header given in the Hardware Reference.
  2. Attach the USB to Serial Adapter to the header.
UART pinout (click to enlarge)

UART pinout

PIN Color Function
1 black GND
2   NC
3   NC
4 green TX
5 white RX
6   NC

PIN 1 is the one closest to the volume button while PIN 6 is the one closest to the power button. The pin functions are documented from the perspective of a USB to serial adapter – the devkit receives serial input on pin 4 and transmits serial output on pin 5.

The board can be powered in the usual way with the serial adaptor connected to your workstation. Depending on your operating system and any other USB devices you have connected, a serial console should appear as a device file such as /dev/ttyUSB0. Connect to this using picocom using this device file instead of the one you would use for a serial connection to the board’s USB C port:

picocom -b 115200 /dev/ttyUSB0

Use the relevant device file instead of ttyUSB0 as necessary.