Re: [linux-delhi] 75baud, baudot, 1.5 stop bits

[mukund <betacomp@xxxxxxxxxxxxxxxx>]

Raj Mathur wrote:
> 
> >>>>> "Prasad" == prasad  <prasadb@xxxxxxxxxxxxxxx> writes:
> 
>     Prasad> Actually, I have used 1 or 2 stopbits, when 1.5 was
>     Prasad> required.  One or the other works , don't remember which.
>     Prasad> Worth giving it a try anyways (no kernel hacking involved
>     Prasad> , and no suggestions boomeranging on me! :-) ).
> 
> I was reading some UART specs yesterday, and apparently you have to
> shove a 0 or a 1 into a specific bit in a specific register in the
> UART to tell it to use 1 or 2 stop bits respectively.  The nice part
> /appears to be/ that if the character size has been set to 5 bits the
> UART automatically uses 1.5 stop bits if programmed for 2 stop bits.
> 
> Can some hardware guru kindly validate this, especially in the context
> of Linux?
> 

Long back (about 8-10 years back) I did lots of experiment with serial
ports and was able to capture teleprinter data to a PC. The teleprinter
(mostly used on news service) requires a 50 baud, 5 data bits and 2 or
1.5 stop bits. In those days also 50 baud was not available (110 was
minimum) so I reprogrammed the clock divider register in 8253 (don't
remember the IC number) and finally could get the teleprinter data in to
the PC. The trick is to set the the divisor in such a way that you get a
error free reception. Then 1.5 stop bit does not matter. The entire
exercise was done in gwbasic with mem and i/o instructions.

In case you need further assistance please let me know. I will again
brush and give you complete solution. 


- -- 
Best Wishes.
- -mukund
http://members.theglobe.com/betacomp/default.html
http://members.xoom.com/BETACOMP/index1.htm



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