tools/examples/basics/blinky_nonblocking/readme.txt

   1 Causes the LED to blink once per second using a non-blocking delay, as well
   2 as constantly checking the UART or USB CDC buffer for incoming data to be
   3 passed to the CLI.  You can connect to the CLI using UART or USB, send and
   4 receive commands, and the LED should continue blinking (as long as a command
   5 is not using the MCU).