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ZedBoard/FMCOMMS2 ADC buffer read problems

Question asked by strack on May 9, 2014
Latest reply on May 13, 2014 by dpu



I'm trying to perform some large-ish reads from the ADC buffer using the AXI DMA in the supplied demo design.  I'm using the IIO_SAMPLE command from Matlab on a Windows PC to attempt to read 2000 samples over the network, however this transfer size causes iio_cmdsrv running on the ARM to hang and the IIO_SAMPLE command fails (no data is returned). I've performed this operation many times for transfers of up to 1000 samples without issue.  A Wireshark analysis of the failed call shows that the return data is being fragmented into two UDP fragments, i.e. two packets each requiring re-assembly.  See attached screen caps for successful 1000-sample transfer and unsuccessful 2000-sample transfer.  Not sure if this related but found it curious. Have I reached some known limitation or is it possible I'm doing something wrong?