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[DPRG] serial baudrate converter

Subject: [DPRG] serial baudrate converter
From: Ted Larson ted at larsonland.com
Date: Wed Sep 8 18:29:49 CDT 2004

Bob and I have been cranking hard, daily on the Robomagellan entry....still
lots of work to be done, and only a couple of weeks left until the contest.
I am hoping to put some pics of it on the website in the next week or so.
It is a monster.  I'll bet it is the largest robot in the contest...we are
very close to the 50 pound limit.  I plan on doing some field trials out at
the local soccer field next week too, so hopefully I can shoot some video of
it roaming around looking for cones using GPS to navigate.

- Ted

-----Original Message-----
From: David P. Anderson [mailto:dpa at io.isem.smu.edu] 
Sent: Wednesday, September 08, 2004 11:45 AM
To: ted at larsonland.com
Cc: dprglist at dprg.org
Subject: Re: [DPRG] serial baudrate converter

Hello Ted, Ed,

"...size of your thumb" sounds good!  

The host needs to send a one byte query and then receive 4 bytes of data, at
around 100 Hz, so a 4 byte fifo (maybe in the uart?) would do it.  I was
hoping for an off-the-shelf solution, Joe's Serial-Converters-R-Us, just add
water?  No?

Ted, how's your Robomagellan comming?  Any pictures?


> Dave,
> Although I am not sure it is the "easiest" method, you could easily do 
> this with a cheap PIC chip with a UART like a 16F628A.  The ideal 
> scenario would be to use a chip with dual UART's on it, but most of 
> them are larger packages and above $10 in price. You would need to 
> code up a FIFO inside, or you would risk loosing data when going from the
19.2k side to the 9.6k side.
> I would hook the 19.2k side to the UART, and then use the interrupt 
> pin B0 on the 9.6k side.  If you have a 'C' compiler for the PIC with 
> a good serial library, then the whole project wouldn't take more than 
> an hour or two to build and test.  If you used SM parts you could 
> probably get the whole thing onto a PCB the size of your thumb. Only 
> thing I would recommend for sure, is use a xtal oscillator, and not a 
> resonator or RC clock...the serial timing in software will be highly
sensitive to how good your clock is.
> Hope this helps,
> - Ted
> -----Original Message-----
> From: David P. Anderson [mailto:dpa at io.isem.smu.edu]
> Sent: Wednesday, September 08, 2004 10:37 AM
> To: dprglist at dprg.org
> Subject: [DPRG] serial baudrate converter
> Howdy
> I have a device that only speaks 19200 baud serial that needs to talk 
> to a device than only speaks 9600 baud, no handshaking either way.
> Is there some easy way to do this?  Maybe with a PIC or such?  Needs 
> to be physically small.
> best,
> dpa
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