To demonstThis little sample program demonstrates sending and receiving UART data on the AtomS3U Grove connector by looping back the two data pins, configured and transmit and receive pins.

To demonstrate that it is working, a random number is sent and when received used to change the colour of the LED. Note that the UART number used is UART1. UART 2 has also been tested and works. UART 0 is presumably used for the USB communication and didn’t work in this program.