Control QGC using RPI

Hi all, I am new to QGC and I would appreciate any assistance that would help me in setting up my RPI (onboard quad) to send command signal to QGC to trigger flight profile change.
I am currently using Pixracer and RPI3 and would love to use QGC to plan for my mission profile using my Macbook.
Can anyone please advise or direct me to any relevant material that would allow me to set up the communication link between a micro-controller (RPI) and QGC?

Any helps are deeply appreciated!
Thanks builders!

You can follow the link to setup mavlink communication through Rpi :