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Ross Arnott

Analog Discovery 2 buffer size change

Question

Hi,

I'm trying to capture a 400kHz I2C waveform for a second or two using the logic analyzer function. Because the AD2  buffer size is small I am using record mode.  When I do this with the default device configuration in the device manager (option 1 16x4k for Logic) I get the error "Samples were lost! Reduce sample rate".  If I reduce the buffer dize and the sample rate I can change the message to "Samples could be lost! Reduce sample rate".

My understanding is that I should be able to operate at 1-2MHz and that it's the USB bandwidth in conjunction with the buffer size that is the limitation. I tried to use the device manager to increase the buffer memory allocated to the logic analyser on the AD2, trying to change to option 4 16x16k, however whenever I do that the AD2 stops capturing data altogether.  When I press record it goes to the "armed" state, but the acquisition doesn't trigger.  I can change back to option 1 and it captures data again.  

This seems like a bug to me, unless I am missing something.  Any suggestions? 

2MHz capture should be sufficient for me and was the reason I bought the device.  Less than that isn't much good for my application.

Thanks,

Ross

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@Ross Arnott,

I asked around and it sounds like the update will be scheduled to release sometime next month. As for the reason why it seems so late in relation to this thread, perhaps there's something else that Digilent is planning to coincide with the update ;).

Thanks,
JColvin

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Yeah, I was a little bummed myself when I learned that is was decided to not release an intermediate solution to address this problem in the mean time. AFAIK, the mid-February timeframe should still be accurate though. 

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