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SubjectRe: Serial custom speed deprecated?
linux@horizon.com wrote:
>> Or we could just add a standardised extra set of speed ioctls, but then
>> we need to decide what occurs if I set the speed and then issue a
>> termios call - does it override or not.
>
<snip>
> Alternatively, you could observe that asynchronous communications only
> requires agreement withing 5% between sender and receiver, so specifying
> a baud rate to much better than 1% is not too important.

To nitpick.
For a 10 bit long word, if the receiver syncs to within 1/8th of the
middle of a bit-time at the start, you've got 2/8th of a bit-time of
disagreement possible, before you are likely to get errors, especially
on limited slew-rate signals. (more modern chips will likely sample faster)
Or 3/80, or 2.5%. If the other side has made a similar calculation, then
you should only really rely on 1%.
5% is the best possible case - that will in most circumstances cause errors.
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