Protocol Decoding on a Streaming Capture

Protocol Decoding on a Streaming Capture, a forum discussion on Cleverscope Mixed Signal USB Oscilloscopes. Join us for more discussions on Protocol Decoding on a Streaming Capture on our Questions forum.

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12 Jan 2021
Posts: 3

I've watched the Cleverscope videos on streaming captures and the one on long-duration protocol decoding. What I'm trying to do is combine the two. I need to capture about 1.5 minutes of 2-way UART 4800 baud communication. I am using digital channels 1 and 2, and have protocol decoding working for each of them. It appears that the longest long-duration protocol capture I can get is 20 seconds. If I switch to a streaming capture, I can go for as long as I want, but then the decoded protocol doesn't display as I scroll through the capture.
Am I missing something to get this done, or is this beyond the present capabilities of the software?

12 Jan 2021
Posts: 477

Hello Geg0,
With Streaming capture there may be many millions of samples. We limit the decode to about 10M samples, otherwise we have memory problems. You have two options:

1. Set the streaming rate that is still useful for decoding, say 10x faster than the baud rate. In your case that would be 50k samples per second. Use Settings/Acquisition Settings/Desired Streaming Rate (the default is 1MSPS). Then the 1.5 mins will be 4.5M samples, which the decoder can cope with.
2. Maintain the high sample rate (1.5mins will be 90 MSamples), but step through the stream piecewise after you have captured it. Say a message is 10 bytes, thats about 10 x 10 (8d, 1start, 1 stop) /4800 = 21 ms. You could step through in 1 second chunks (1MSamples), and see the messages in that chunk, then step to the next.

We have two changes that we plan when we get time:
1. Make the decoding work on the tracking display, so that you can step through just by using the tracer on the Scope Display, with the tracking display set to 1 sec (or similar) wide.
2. Create an edge record on the fly that just saves edges, which will be much more compact. This will make decoding large streams easier.

I hope this helps.
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