Need guidance for layer1 and layer 2 connection in firmware

i am trying to port mobile app on phone it self as a firmware but unable to find out how exactly L1 on phone communicate with L2 L3 on pc. please help me with that. -- Akib Sayyed Matrix-Shell akibsayyed@gmail.com akibsayyed@matrixshell.com Mob:- +91-966-514-2243