Hi,

beware! There is normally no such thing as "Start Byte" on the ISO Layer
2. I guess you meant start bit. It is, of course, better to use an ISR to
receive a complete byte if you have time enough to spend for the
ISR. However, you should implement either some hand shaking mechanism or a
ring buffer, if there are more bytes to come. Polling is simpler, but a
pain in ass if there is a probability to break the line.

Regards,
Imre


On Wed, 10 Jan 2001, Freddie Leaf wrote:

> I'm interested in bit banging Asynchronous Rx and Tx serial communications
> on a PIC16F84.  I understand the serial protocol, but need some advise on
> the Rx implementation algorithm.  Here are a few questions..  If anyone
> has done this and would share their code I sure would appreciate it.
>
> 1)For the Rx algorithm, what is the best was to watch for the Start Byte?
> Is it best to use an interrupt or to keep polling the line for a
> transition.
> 2) Once you think the start byte is coming, what is the best way to be
> sure.  ie, do you look for a pulse that is equal to 1/baud rate? or do you
> assume that any transition is the beginning of the Start Byte?
>
>
>
> =====
>
>
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