EVAL-AD1938AZ Communication with SigmaStudio Software and MCHStreamer


My team and I recently purchased an EVAL-AD1938AZ board and we are having trouble connecting it to our DSP.

Our DSP is the MCHStreamer from miniDSP. The goal right now is to have an analog signal as an input to the EVAL-AD1938 via one of the 3.5mm audio jacks and then have the converted digital signal sent to a PC via the MCHStreamer.

Right now, every time we try to write to the EVAL-AD1938AZ using the SigmaStudio software, it seems as if the write was successful, but then when we pull the current settings from the board, it seems to have reverted back to its default state.

Does this behavior sound correct or when we get the current state of the board should we be able to see the same values that we wrote to the board?

As far as we can tell we have the EVAL-AD1938 configured the way we would need it to be in order for the MCHStreamer to be the master and the AD1938 to be the slave, but we aren’t getting any audio from the ADC output.

Thanks for any input.

One should generally be able to read back written values; an inability to do so suggests a failure of the write process, or erasure in between the write and read operations. I see little in the way of non-volatile memory on the board, so a reset or power cycle of some sort could account for the latter.

An inability to successfully read back register settings is a fair indication that the device is not, in fact, getting correctly configured. You’d probably want to focus on sorting that part out first.

After that, there are questions of:

  • whether your chosen register settings actually -are- correct for your intended purposes
  • whether or not the hardware settings on the '1938 board are correct
  • whether the connections to your interface device are correct
  • whether the software component of your interface device is in proper order

Every link in the chain needs to be intact in order for the whole to function. Look at each in turn, compare result against expectations for the inputs provided, and if you’re not getting what you’re expecting, look for explanations, with the understanding that wrong expectations or mistaken beliefs (ex. “the power supply is turned on”) are among the most common.

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