Roy Smith wrote:
In article <49970ce7$0$1665$742ec...@news.sonic.net>,
John Nagle <na...@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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