Can Python serial support run at 45.45 baud?

John Nagle nagle at animats.com
Sat Feb 14 22:25:37 CET 2009


Roy Smith wrote:
> In article <49970ce7$0$1665$742ec2ed at news.sonic.net>,
>  John Nagle <nagle at animats.com> wrote:
> 
>> At the hardware level, there's a clock rate, a counter, and a divisor, 
>> so arbitrary baud rates can be set.
> 
> Is that really true of modern hardware?  The last time I looked at serial 
> port hardware, UARTs took a base clock rate and divided it sequentially 
> with flip-flops to get all the possible rates (they usually had some ugly 
> logic to generate 110).  You were limited to the specific rates the 
> hardware gave you.  Is that no longer the case?

    It is, but the traditional serial clock rate is 115200 Hz, so you can use
any subdivision of that as a baud rate.  The divisor for 45.45 baud is
something like 2535.

    Some exotic serial port devices use a 16MHz clock; I've used those for
supporting SICK LMS laser rangerfinders at 500,000 baud.

					John Nagle



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