AVR-Chat

One technique I've used with great success in RC
oscillator Nitron devices is  to use the target to
itself calibrate the half-bit delay loop.I get the
target to send $7F to the micro at the start of the
serial session. The serial line is low for exactly
one-bit period, which is used to set the internal
delay count variable (in EEPROM). Then the micro will
send at the detected bit-rate.
Note that this also gives auto-baud detect including
for non-standard baud rates.

Cheers,
Samir.

--- David VanHorn <microbrix@gmail.com> wrote:
> Generally speaking, you need at least a resonator,
> or crystal, to do accurate baud rates.
> You have to factor in ALL the error sources.  First
> you have to allow the other device at least half
> of the error budget,then figure your
> divisor error, then min and max tolerance on the
> clock. When you add it all up, the internal RC
> isn't good enough for serial.



       
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