Okays, well I would do this, except whatever I try to send, the
computer only recieves lots and lots of ones, which it decodes as 03h
(111), and FF (11111111).  I think there's probably some other problem
than the baud rate.

On 5/2/05, Russell McMahon <apptech@paradise.net.nz> wrote:
> > I know nothing about the IDC2, but I *do* know that an RC-osc
> > will have a hard time to give you any relailable serial
> > communication.
> > You need *some* crystal (or maybe resonator) based osc to be able
> > to use the UASRT (or maybe the prec internal osc block on newer
> > devices).
> 
> You need about 50/N% clock stability overall for async operation.
> better is better.
> So for 1+8+1=10 bits you need 50/10%=5% accuracy.
> 
> If your PC end crystal is approaching 0% in error then you get most of
> that 5% at the microprocessor end. Some (but by no means all) RC
> clocks will give you that sort of accuracy across voltage, temperature
> and time.
> 
> But, as Jan-Erik says, something better than RC is a really good idea
> if you can manage it. A resonator is fine.
> 
> If you aren't at all sure what your baud rate is then Murphy says it's
> almost certainly wrong.
> (If you ARE sure then Murphy says it may be wrong :-) ).
> 
> If you have a scope then the shortest bit length will tell you what
> the baud rate is if you send anything with a 010 or 101 sequence in
> it.
> 
> No scope?
> Set data to, say, $00, with a good gap between bytes.
> If you can send individual characters without CRLF it's ***MUCH***
> easier to work out what's happening.
> If you are sending slower than you think then the receiving routine
> will see an $00 followed by a second character with b0xxxxxxx. ie
> 01111111 or 00111111 or 00011111 etc depending how slow. if reaaally
> slow it will se several $00's followed by a b0xxxxxxx.
> Having your PC end able to display the result of receiving $00 helps a
> lot here :-)
> 
> So, if you send 1 character from the uP and see several characters,
> odds are it's too slow. Double sending data rate and try again?
> See $00 - it works.
> Still see 2+ characters, double clock rate again.
> 
> If you are sending faster than you think the PC will see N 0's and M
> 1's / 1<=N<=7, M=8-N.
> Decode the displayed character and you can see how much faster it is
> than you expected.
> 
> Using a scope is much easier.
> 
> 
>         RM
> 
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