AVR-Chat

John Samperi wrote:
> At 12:27 PM 17/12/2005, you wrote:
> 
>>RS485 requires three wires but rs232 only needs two.
> 
> ??? How do you figure that? Let's see RS232 minimum Tx,Rx and
> return ground.

Uni-directional or half-duplex (with tristate TX) only needs two wires.
Full duplex requires three.

 > RS485 data+, data-  and return ground. If you
> use a transformer coupled RS485 you don't need ground (2 wires)