Set up all internal ADCs of the efusA9X module to get it working.

  • Hello,


    I would like to test all four ADC channels (ADC_D, ADC_C, ADC_B, ADC_A) of the efusA9X module. So far I checked the adc example and the device tree. According to the example the ADC will be handled via device files (/dev/mvf_adc.?). But I could not find these in the sysfs. [1] and [2] shows some device tree nodes. [2] tells me that the ADCs are already in use for some other functions. But [1] does not create the missing decive files in the sysfs.


    What I am missing is a example of a device tree node to inform the kernel about the ADCs. Is there already an example for this or how do I get the device files into the sysfs?


    [1]:


    [2]:

  • VADC is something different, this is the analog video input (Video A/D Converter). So [2] is not relevant in this case.


    The device tree setting in [1] is actually all that needs to be set for ADC to work. There are two channels (ADC_A, ADC_B) on adc1 and two channels (ADC_C, ADC_D) on adc2. You will find the analog values in /sys/bus/iio/devices/iio\:device0 and /sys/bus/iio/devices/iio\:device1 respectively.


    BUT: On a regular efusA9X, the ADC channels are not connected. For some reason I also do not understand, a resistor network that connects the ADC channels to the connector pins is not mounted and therefore the input pins are floating. I have asked the hardware department for a reason and they will check. Maybe ADC will be available on future variants. But for now, ADC can not be used without hardware modification.


    Your F&S Support Team

    F&S Elektronik Systeme GmbH
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