Pang wrote:

> I need to implement a single wire communication between
>  two modules with uC. The data transfered at any one time
> is just a High or Low. Since the data transfered is just one
< state ( high or low ),...

   Why not use 4 levels (0 - 4 - 8 - 12V) to transmit / receive?
A schematic is rather simple.
   Or usual telephone idea as described in AN854 Connecting
a PICmicro Microcontroller to a Standard Analog Telephone
Line?

   Good Luck,
   Mike.

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