[time-nuts] Rapco 1804M - serial problems?
hmurray at megapathdsl.net
Tue Oct 18 03:36:11 EDT 2011
> So, remarkable as it is, it seems that either the serial chip is bad, or
> bad data is being sent to the chip.
You might collect a pile of errors and analyze the bit level changes.
I think some of your errors were / changing to a ?. That's hex 2F changing
to 3F, or picking the 10 bit. How many of the other errors did the same
I think serial ports are least significant bit first, so a scope would see
11110100 changing to 11111100. That would be a reasonable error on a serial
port if the high-low-high transition was slow and didn't get low enough.
(But 4800 is really slow and you said the cable was short. Any problems
should be obvious on a scope.)
Do you have any other serial ports where you could try it? How about a
serial-USB dongle? Or maybe even a shorter cable?
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