Jim Jackson wrote:
>I've found the free running timers on the ts7200 allow my box to keep an
>accuracy of the order of 1 sec in a couple of days.
>
>
I have not experience (yet, waiting...) on ts72xx, but the average
crystal found from standard x86 PCs is a better thermometer than a time
keeping device. (crystall oscillators have quite large temperature
cofficient). If you have (inter)net available, you can use NTP protocol
to syncronise clocks, you get some 1-10 ms accaracy that depends quite
much on network and end system load.
If you need more accurate clock, then you need to use GPS (or CDMA, if
you are in US) clock that can provide you a pulse-per-second output and
maybe 10 MHz clock too. Note, that a handheld navigation GPS does not
provide accurate time output, so you need some real clock unit. Of
course, you could also use some stabile oscillator, but those are not
cheap either.
Accurate (i.e. microsecond-level) time-keeping in Linux (or some other
general OS) is a quite demanding task because of various asyncronous events.
Markus | <>
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