[time-nuts] TIC232 Detailed Operation
Glenn
glenn at net127.com
Sun Aug 13 18:58:36 UTC 2006
I've never programmed a PIC, nor do I know much about TI measurements.
But, if you wanted 100 ps resolution, would it make sense to average five
125 samples?
thanks,
glenn
Richard H McCorkle wrote:
>By selecting a known sample time for the XO speed used, the LSB
>of the displayed data has a known time value. By default the 60-second
>sample period gives an LSB of 1.04ns. No dividing by the sample time
>or other scaling needs to be done to the count displayed, it is already
>scaled by the XO speed and sample time used. By changing the
>sample time to calibrate the reading, the count can be scaled to read
>directly. For instance, accumulating 625 samples with a 16 MHz XO
>speed would result in a count with an LSB of 100 ps. Since the Simple
>Time Interval Counter only goes to 256 samples, averaging 250 samples
>would give an LSB of 0.25ns and an output count displayed once every
>4:10. An LSB value of exactly 1ns would require 62.5 seconds per
>update. Because partial sample times aren't allowed, a 60-second
>value was chosen as default giving an LSB of 1.04ns and an output
>count displayed once per minute.
>
>
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