[Coco] 6551 at 115200 bps

Mike Pepe lamune at doki-doki.net
Sun Jan 18 21:35:45 EST 2009


The TxC and RxC pins (5 & 12) are independent of the crystal oscillator
and internal baud rate generator.

The way to accomplish my original design would be to use an external
1.8432MHz oscillator and feed it to TxC, RxC, and the XTAL1 pin. It's a
pretty simple mod. Actually I may just have to try this one out myself
and see if it works like the datasheet says it should.

> -----Original Message-----
> From: coco-bounces at maltedmedia.com [mailto:coco-
> bounces at maltedmedia.com] On Behalf Of Roger Taylor
> Sent: Sunday, January 18, 2009 4:35 PM
> To: CoCoList for Color Computer Enthusiasts
> Subject: Re: [Coco] 6551 at 115200 bps
> 
> At 05:49 PM 1/18/2009, you wrote:
> >At 05:20 PM 1/18/2009, you wrote:
> >>Roger,
> >>
> >>If you were to take the 1.8432MHz clock and feed it right into the
> >>6551's TxC and RxC (clock) pins and set the chip to external clock
> mode,
> >>you'd get 115,200 bps out of it.
> >
> >With the 1.8432 mhz crystal connected at XTAL1 and XTAL2 where it's
> >supposed to be, setting the baud rate to 0000 achieves the same
> >thing, or am I missing something?
> >
> >Are you saying the E signal could be sent to TxC and RxC to achieve
> >57600 bps and 115200 bps based on whether the CoCo is at normal or
> >double speed?
> 
> Scratch that last question.  E wouldn't be 1.8432 mhz either way.  I
> guess TxC/RxC has a different function than XTAL1/XTAL2. I don't know.
> 
> --
> Roger Taylor
> 
> http://www.wordofthedayonline.com
> 
> 
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