Mr. mattew zac:

You wrote:
does anyone know if it is possible or someone already did it (wrote serial software for 8051)?

The answer is yes. It was done way back in May 17, 1994, by Dave Dunfield. He wrote some assembly software entitled "Bit-bang" serial I/O functions for the 8051. You can get it at the below site.

I have used it for years and it works well.

http://www.code.archive.aisnota.com/downloads...t-bang.asm

Good luck,

Charles Bannister