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Staale

Significance of gray blocks in signal grid?

Question

Getting acquainted with WaveForms and my new Digital Discovery. I'm looking at SPI signals and see gray blocks in the signal plots. (See enclosed images.) What is the significance of these blocks? Too fast oscillation vs sampling rate? However, mouse-over doesn't show any change in values across the block.

Sorry if this is an obvious question. :)

Thanks for any input.

Staale

Overview:

gray-blocks.png.72d7e6485bafe2b1a43f9607c72f709d.png

Same grid, max zoom:

max-zoom.png.3885c11080a2f0b67791bb566c818dd8.png

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3 answers to this question

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Hi @Staale

Beside the normal samples given by the sample rate, noise samples are also stored to indicate glitches, more than one transition between two acquired samples.

This seems to be an issue with noise detection on sample rates which are not divisions of 100MHz, like 57.14MHz

Until this is fixed please ignore (uncheck) this noise option or select 800, 400, 200, 100, 50, 33.3, 25... MHz sample rates.

i1.png

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Hi @Staale,

I have tagged the engineer that will have the best response to your question( @attila). I don't believe scrolling over this portion of Waveforms will not have a specific value. Looking at the your screen shots it looks like the hardware you are scoping is in a meta-stable state. I know that different hardware can have unique situations like our PmodAD3 has Digital-to-analog glitch impulse that is talked about in this forum thread. What hardware are you looking at?

cheers,

Jon

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Hi @jpeyron,

Thanks for your reply. The master generating the serial signals in the images is an i.MX6 ARM CPU.

I'm away from my desk right now so I can't verify, but could it simply be that I've managed to disconnect the ground connection between the Digital Discovery and the board without noticing? Would a missing gnd connection result in signal behavior like what I'm seeing?

Thanks,

Staale

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