Verifying memory size of logic analyzer?

Discussion in 'Embedded Systems and Microcontrollers' started by spinnaker, Jan 28, 2014.

  1. spinnaker

    Thread Starter AAC Fanatic!

    Oct 29, 2009
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    I am supposed to have a 256K logic analyzer. How can I verify that it is really 256k?

    Would I just connect a known frequency square wave to one channel and see how long it samples? But how do I know how much memory is taken per transition?
     
  2. spinnaker

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    Or would I simply use my internal clock and see how long I can sample?


    This is what I get with 100KHZ clock

    Memory Sample Time
    2K 10.25ms
    16K 81.9ms
    32K 163.85ms
    64K 327.69ms
    128K 655.37ms
    256K 1.31s
     
  3. Brownout

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    Jan 10, 2012
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    The sample time should be memory_depth/(sampling_frequency*number_channels) Thus, for 100K samples/sec, you should get 262144/100K = 2.62S for single channel.

    That is, if the memory size is given in units of samples, which is usually the case.
     
    Last edited: Jan 29, 2014
  4. spinnaker

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    Look at my table above. Looks like I am getting about half of that.
     
  5. Brownout

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    Are you sampling only one channel? Maybe you inadvertently have a scond channel active???
     
  6. spinnaker

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    I see the issue. There is a setting called Page. By default it is set to 1. I have choices 1-15. If I set it to anything but 1 I get twice the sample period.

    I know Page has something to do with the trigger, but I have no idea what. The help file does not seem to explain it.
     
  7. spinnaker

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    Oh I am only measuring one channel too. But strange if I add a channel and I have page set to something other than one, I still get 2.61s for 128k. It almost seems like memory setting is per channel?
     
  8. Brownout

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    I've never seen this option on any LA I've used. Sorry, can't help there.


    That could very well be.
     
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