On 03/30/2011 06:58 AM, Chris Albertson wrote:
On Tue, Mar 29, 2011 at 7:30 PM, Lenny Story<[email protected]> wrote:
All,
Ok... so i'll just make it a rising edge pulse of ~500ms. That should be
enough time for a linux box to detect it.
I would vote for a non-symetric waveform so you can see if it is inverted.
I've found 200 ms high, 800 ms low quite useful for scopes. :)
For other signals I do just 50% and it works well, but sometimes you can
see reversed polarity and you have to spend time to figure out if it is
inverted or not. Wastes a lot of time.
I don't think the pulse is detected by software. It's an interrupt.
The Linux PPS handler reads the clock and stores it. Latter software
that "reads" the PPS is given the stored time tag. I'm pretty sure the
interrupt hardware is trigged by the edge. Choose the length so a
human (you) can detect it
Agree.
Cheers,
Magnus
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