If you don’t know what your sending and receiving over an interface, then other than through pure luck, or an extended integration phase composed of ‘tiger teams’ and an infinite budget, don’t expect the problem solved quickly. In today’s market, the once simplistic embedded processor with a few interrupts now has every interface conceived to man compressed into a single microchip no bigger than your thumbnail. Without a strategy to attack this problem, the harsh reality is that your project is doomed to fail.