[Coco] Max baud rate for 68681 in MM/1?

[Dave Philipsen]

I have personally used a 68C681 UART in a 68HC11-based system that 
transmits DMX512 theatrical standard lighting data at 250 kbps 
(RS422/485).  It is tried and proven and currently running in about 400 
different locations in the US and a few other countries.  It is using a 
4 MHz clock as the BRG.

Dave


On 1/31/2016 3:33 PM, Joel Ewy wrote:
> I read ambiguous information about the 68681 on the MM/1's I/O board.  
> Does anybody have a definitive word?  Page 2-5 of the MM/1 technical 
> manual claims that it can be run at "1 megabytes per second" 
> (seriously 8M bits/sec?), but the table on page 9-2 and the text on 
> 9-2 state that the maximum baud rate is 34,800.  Is this a pragmatic 
> maximum based on the CPU's ability to service the DUART's on-chip 
> buffers without interrupt-masking trickery, is it the real hard 
> maximum for the 68681, or is it a hard maximum imposed by the MM/1's 
> hardware?  Anybody have any insight?
>
> JCE
>
>


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