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Altera_Forum's avatar
Altera_Forum
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8 years ago

Continuous signal tap capture?

Hi,

I am wondering if there is a way to continuously get data from probes in signal tap.

I have explored the mex matlab signal tap functionality in a loop but I lose samples.

I have briefly tried tcp/ip tcl server and signal probes functionality and I lose samples.

Are there double buffering schemes in signal tap?

Do I need to implement my own system (double buffered memory) to not lose samples?

The signal I am hoping to capture continuously is a 16 bit word updating at 56khz.

Thanks!

2 Replies

  • Altera_Forum's avatar
    Altera_Forum
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    8 years ago

    I think Signaltap is going to struggle. JTAG has a lot of overhead associated with it and you're trying to recover @ 1Mbsp of raw data.

    If you're not already you could try running your JTAG chain faster. See: "how do i change the clock frequency of the usb-blaster ii download cable? (https://www.altera.com/support/support-resources/knowledge-base/solutions/rd06242013_922.html)".

    Beyond that, I think you're going to have to come up with a more ingenious solution. Buffering - yes. But for how long do you want to "continuously get data"? JTAG will remain a bottleneck (assuming that's the issue) in a continuous scenario, regardless of any buffering.

    Cheers,

    Alex
  • Altera_Forum's avatar
    Altera_Forum
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    8 years ago

    Instead of trying to overcome the limitations of the JTAG, you could make changes to how the SignalTap capture buffer is set up. Choose to capture more samples, or segment the buffer to capture repeating events. You can also use sample filtering along with these features to capture only the samples you are interested in, making more efficient use of buffer space.