Re: Slightly unmatched UART frequencies

Hi Rick et al.,

rickman <[EMAIL PROTECTED]> wrote:
> Since the transmitter must use a full 10 bits,
> then the buffer between the receiver and transmitter will overflow at
> some point.

I'm glad someone else agrees with me!  I think we'd all agree now, then,
that either you need an adjustable output clock or the part to transmit with
a shortened stop (or start) bit, which is effectively the same thing as
adjusting your output clock rate anyway.

> This is a problem that is found in communications systems.  All units
> must run at the same rate, but may use a different reference.

> Some systems try to buffer this out, but that only postpones the
> problem.  Most systems use a common reference that is very accurate and
> stable.

...or they force the data to be encoded with its clock so that a PLL can
extract the exact frequency reference and work with that.

> In the case of the OP, the first channel can use two stop bits and the
> echo channel can use one stop bit.  This may not be pretty, but it will
> work.

It certainly will but the price is a reduction of ~10% of the average
throughput!  Of course, that may be negligible depending on the system.

---Joel