This firmware translates a PS/2 mouse to a USB mouse. The translator firmware is entirely interrupt driven (with the exception of sending the data via USB to the host.) An interrupt is generated when the PS/2 start bit is received, at which time the firmware will begin its receive routine. In addition to this interrupt, every 168ms a timer overflow interrupts the main program and implements one state of the mouse state machine. This state machine handles sending bytes to and translating bytes received from the PS/2 mouse automatically. All of this is done in the background while the main program runs in the foreground. The only operation that the main program implements is sending mouse data to the PC via USB.
