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howto capturing edge until the last one

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howto capturing edge until the last one

Postby pupillo » Fri Feb 23, 2018 6:02 pm

Hi, I've a digital signal which at a certain point stops working (it doesn't change anymore) and I'd like to capture the latest period of time (let's say 10 microsec) until the last edge, in order to see what happened before it stopped. I tried with "repeat" trigger mode but I'm not sure it does what I need. I want to be sure that what I see in the waveform is the latest part, without missing anything.
How should I do?
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Pupillo
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Re: howto capturing edge until the last one

Postby Martyn » Fri Feb 23, 2018 7:07 pm

It would be helpful to see what the signal looks like, a sketch will do, if you can't capture with the scope.

Please let us know which scope you have as well.
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Re: howto capturing edge until the last one

Postby pupillo » Sat Feb 24, 2018 4:17 pm

Hi,
it's a simple MOSI output from an SPI bus with a clk running at 12Mhz. So, 0 / 3.3v . Very good signal, no noise. As the clk is at 12mhz, my signal can change as often as 1/12Mhz.
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Re: howto capturing edge until the last one

Postby pupillo » Sat Feb 24, 2018 4:19 pm

Sorry, I was forgetting, my scope is a 3206D
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Re: howto capturing edge until the last one

Postby Martyn » Sat Feb 24, 2018 8:22 pm

Sounds like you need to use one of the two Dropout triggers from the Advanced Trigger menu.
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