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fmcadc2 - iio scope

Question asked by Pablo.Leyva on Apr 2, 2015
Latest reply on Apr 13, 2015 by Pablo.Leyva


I am working with an ad9625 ADC in a development board (not fmcadc2), to test the board I am using the fmcadc2 reference design, just to be sure that everything is working and be able to use de iio-scope to adquire the data.

The problem is that I can run linux and change the configuration of the core (SPI and AXI) but I am not able to see a correct waveform in the oscilloscope.


To see the values of the sampled data I am working with the ILA core and I reconstruct the samples manually. For this test the input signal is a half LVDS clock (just the 'p' part); Square, 300mv, 2Mhz.


The blue signal is the LVDS input, and the green one the signal at the end of the Front-end (input of the ADC).




This first capture was made after the configuration of the core with the no-OS code. and everything seems to be working, until now this was the only way I can work, but thanks to mhennerich now I am able to use the linux system.




After running Linux (same input) the reconstructed signal is significantly different.




And if I launch the iio-scope to save the data for some postprocessing... this is what I am getting:




To be sure that the communication with the ADC is working I change the output mode to test_mode: RAMP




And in the ILA core we can see a really nice sawtooth wave:




But in the scope...




I have tried with different wave frequencies, shapes, etc.. but the results are always similar to this ones.

Do you have any idea of what could be the problem?


Thanks in advance


- Pablo