Waveform SDK setting AnalogIn Filter

[alpanth]

	int st = 0;

    int fsfilter;
    st = FDwfAnalogInChannelFilterInfo(DWF.hdwf, &fsfilter);
    assert(st);

    if(IsBitSet(fsfilter, filterAverage))
    { 
        st = FDwfAnalogInChannelFilterSet(DWF.hdwf, 0, filterAverage);
        assert(st);

        FILTER filter;
        st = FDwfAnalogInChannelFilterGet(DWF.hdwf, 0, &filter);
        assert(st);

        assert(filter == filterAverage);
    }

Hi,

I am using ADP3450, where I am trying to set the average filter on channel 0 (first thing after opening the device).

It is always failing at the last assert when comparing the filter. Where it should be set to average but it is set to normal.

Is there something wrong with the code or what could be the problem here?

 

Best regards, Alex

 

 

[attila]

Hi @alpanth

Probably the sample rate (FDwfAnalogInFrequency) is at maximum, = system frequency (100MHz), and due to this decimate sampling is used instead of decimate. With external sampling clock (FDwfAnalogInSamplingSource) averaging is similarly changed to decimate.

[alpanth]

Indeed thank you is there some indicator that i missed which would have pointed me to this? Or did I just miss it in the documentation?
Because just from the API calls / checking if it was set with the get method as recommended in the doc I could not know that the sample rate is initially at max. In turn "blocking" the average filter.

Edited August 1, 2023 by alpanth

[alpanth]

Similar problem with "FDwfAnalogInChannelRangeSet" and Get.

I used the provided "analogin_acquisition.cpp" example and just called "FDwfAnalogInChannelRangeGet" after the Wait(2) to check if the range on channel 0 is actually set to 5 V.

But the range I get back is always 54.49315154 V.

Below part of the example with the get method added.

    // enable channels
    for(int c = 0; c < cChannel; c++){
        FDwfAnalogInChannelEnableSet(hdwf, c, true);
    }
    // set 5V pk2pk input range for all channels
    FDwfAnalogInChannelRangeSet(hdwf, -1, 5);
    
    // 20MHz sample rate
    FDwfAnalogInFrequencySet(hdwf, 20000000.0);
        
    // get the maximum buffer size
    FDwfAnalogInBufferSizeInfo(hdwf, NULL, &cSamples);
    FDwfAnalogInBufferSizeSet(hdwf, cSamples);
    
    rgdSamples = new double[cSamples];

    // configure trigger
    FDwfAnalogInTriggerSourceSet(hdwf, trigsrcDetectorAnalogIn);
    FDwfAnalogInTriggerAutoTimeoutSet(hdwf, 10.0);
    FDwfAnalogInTriggerChannelSet(hdwf, 0);
    FDwfAnalogInTriggerTypeSet(hdwf, trigtypeEdge);
    FDwfAnalogInTriggerLevelSet(hdwf, 1.0);
    FDwfAnalogInTriggerConditionSet(hdwf, trigcondRisingPositive);

    // wait at least 2 seconds with Analog Discovery for the offset to stabilize, before the first reading after device open or offset/range change
    Wait(2);

    double range = 0;
    FDwfAnalogInChannelRangeGet(hdwf, 0, &range);
	printf("range: %f\n", range);

 

[attila]

Hi @alpanth

Yes, the range and offset get returns the actually available full scale ADC range and the configured offset DAC voltage.
This is useful to know the reading resolution, where does the signal clip, to convert the samples to voltage units in case the 16bit data function is used...

[alpanth]

Hi @attila,

right so in case of the ADP3450 there are only two ranges (~2V and ~50V), so two possible return values from the "FDwfAnalogInChannelRangeGet"?

Meaning there is no actual difference in setting a range of 5 or 50 V?

[attila]

Hi @alpanth

Yes.

[alpanth]

Okay thank you!