Re: Zilog 8530 maxspeed?
> hm, but what about 57600bps? modems support it, all SW also.
> Should I believe that Z8530 can do 38400, 76800 but NOT 57600bps?
> With Siemens 82532 serial controller you can do all speeds w/o
> any problem (except 76800 of course :)
The Z8530 has no problems with that, but with a clock input of 4.9152MHz
as on sparcs you can reach 57600 with 12.5% error, namely with a BRG
divider setting of 1. This will give an overall post division by
((1 + 2) * 2) = 6, yielding a bitrate of 4915200 / 16 / 6 = 51200.
Compared to that you will get 76800 with a divider setting of 0 like
this: ((0 + 2) * 2 = 4, 4915200 / 16 / 4 = 76800.
It's not only a problem of speed and fifo depth, but also a problem
of integer mathematics.
The SAB82532 has an input clock of 29.4912MHz on the Ultras, and also
a much more flexible BRG divider section, so it can hit more common
baud rates up to B921600 without problems (yes, I tested this).
Eddie C. Dost
ecd@skynet.be
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