Reading packets?

[osnap]

Hello, i have a question for anyone that can help:

I have an ATmega88 and im suppose to receive a 3-byte packet and each byte is 8 bits. This packet is going to be sent to a single pin, but i have limited knowledge of packets, i now i can read a pin's state high/low. But how do i read a byte? does it alternate high/low or something?

Thanks for help 

[Admin]

Hmmmm what is sending the data?

I would assume the data is being sent to the UART of your ATmega88.

Im using AVRlib's rprintf code to do it . . .
http://www.mil.ufl.edu/~chrisarnold/components/microcontrollerBoard/AVR/avrlib/



edit: I cant spell 'sending' . . .

[osnap]

Its a PS/2 mouse, i wanna use its sensor

idk what UART is im going to read the datasheet about that, thank you <3