Hi there,

If you are confirming the link between the input and output data stream then to decode the input data stream you have to:

1) take the current bit and add with the previous bit by module 2 (in other words, logical exclusive OR, i.e. 0+0=0, 0+1=1, 1+0=1, 1+1=0);

2) put the resulting bit into the output data stream;

3) repeat items 1) and 2) for the next input bit.

About 5 years ago I wrote the real coding and decoding programs for i80C85 microprocessor. I suppose it is easy to rewrite them for 8751 microcontroller.

By the way, the coding method above is named relative phase modulation. It was offered by Russian radioengineer Petrovitch and since it is used in communication technics.

Good luck,

Igor