Re: Why should I (not) use an internal oscillator for 8-bit micros

From: Neil Bradley (nb_no_spam_at_synthcom.com)
Date: 08/16/04 

Date: Sun, 15 Aug 2004 17:17:50 -0700

"Doug Dotson" <dougdotson@NOSPAMcablespeed.NOSPAMcom> wrote in message
news:ismdnTKuDKd_T4LcRVn-hQ@cablespeedmd.com...
>I believe that UART stands for "Universal ASYNCRONOUS Receiver
> Transmitter". You need to go back and study the difference between
> sync and async.

Nope, I understand the concept perfectly. When using a UART, it's required
that both sides of the serial transmission be synchronized. If you don't
believe me, try using a crystal at a low baud rate with a 20% tolerance.
Devices won't be able to talk to it. When the byte comes is the asynchronous
part, and that wasn't even the topic being discussed.

The question was in reference to the baud rate generating clock, not when
the data comes in. For the period of the byte transmission, both sides must
be synchronized. There is no common clock between them. If you have separate
clock and data lines, the clock can vary wildly with no adverse effect on
communication. No synchronization between devices needed. Is this a hard
concept to grasp?

You do know that the words synchronous and asynchronous can mean different
things depending on the context, right?

-->Neil

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