solarwind wrote:
>> :) been explained in some posts.
>
> Yeah, well, I'm confused. People say listen to your own transmission.
> Then they say it wont work. What do I do?

People who say you can't listen to your own transmission, are trying to 
confuse you. :) Yes, it can be a problem, but for now assume that you can 
tell a "1" from a "0".

So, how do you detect a collision*? Like this:

- Assume that "1" is recessive, and "0" is dominant. When both are 
transmitted, "0" always wins.
- Transmit a "1"
- Wait a short time (say, 1/10 of a bit)
- Read the output (the assumption here is that your Rx pin is connected to 
your Tx pin).
- If the output is "0", you lost arbitration. Stop transmitting, and wait 
until the bus is idle again.

Vitaliy

*In this case, there really is no collision, we just say that you "lost 
arbitration". A collision implies that the message is destroyed (like it is 
in Ethernet, for example). 

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