The Creazyflie Packet eXchange protocol is used to send data to/from the GAP8 from/to other target systems, like the STM32, ESP32 or the host computer. For more information on the inner workings of CPX, have a look at the CPX documentation.
Using CPX
The CPX API available in the GAP8 can be viewed in the cpx.h header file. From here it’s possible to send/receive messages as well as print text to the Crazyflie client console.