I observe JLS GPIO inputs ringing quite often, here is example screenshot. [image] In most cases it is not much of a problem, since ringing lasts few usec and I can filter it out in digital post-processing. But sometimes when I’m trying to capture short pulses, like one that marked by double-circ…

Hi @inlevis ! I have a few questions to help figure things out: Are you using a Joulescope JS110 or JS220? Am I right in estimating that you want to measure a pulse that only lasts for under 10 µs?

This is JS220. No, I’m not measuring short pulses. I use pulse as substitute to an edge, just as a mark on a time line. I measure time between edges which is much longer than 10us. However, if I was measuring pulse duration, then it might be difficult to do if pulse is shorter 10us.

Thanks for the info. With the JS220, are you connecting both the Vref and at least one GND signal to your target board? The JS220 uses the external Vref by default, which must be connected. Note that the Joulescope UI 0.10.x does not yet have full support for the JS220. We are working on a versi…

I connected both GND wires but did not connect Vref, my bad. With Vref wire connected to +3.3V on my board I still observe ringing, though not as bad as without Vref connected. Here is example screenshot [image]

Hi @inlevis - It does not look like connecting Vref made much difference. It tends to get very, very weakly pulled to 3.3V, so it was probably working correctly originally. Summary The JS220 FPGA packs bits in a little-endian order, but the host software (as of Joulescope UI 0.10.13) unpacks bits …

Ringing GPIO in0 and in1

Technical Discussion

mliberty June 15, 2023, 5:57pm 7

Hi @inlevis - This should be fixed in Joulescope UI 1.0. Please post again if you continue to see the issue!

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Ringing GPIO in0 and in1

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