In order to build it, you need ChibiOS with the ST libraries in the ext directory, which you can download here:
Update: The ST libraries are no longer required, but you can still use the ChibiOS-version above if you’d like. It should work just as well with the official version.
In this example, there are two threads that send and receive RF packets between two RF boards. If this program is uploaded to two RF boards, the red LED on each board should blink because the other board sends packets to switch it on and off and vice versa. The green LED is on as long as the board receives acks from the other board. Auto-ack can also be switched off – then the green LED should be on all the time.
This example also emulates an USB modem when the USB cable is plugged in, so you can use you favourite serial terminal to connect to it. The baudrate is ignored and does not matter. On Ubuntu, it will show up as something like /dev/ttyACM0 (or 1 or n) depending on whether you have other USB modems.