Imp004m DFSDM functionality

As the use of DFSDM would greatly simplify (and reduce component cost) our design that needs an isolated ADC, the use of the DFSDM functionality seems very interesting. 2 questions:

  • any recommended compatible ADCs that you have tested/tried with ?
  • when is the impOS 38 going to be available to production (as the API only seems to come then)


Generally, this is intended for audio use - and hence is intended for use with digital mics. Our system test setup uses an audio ADC (so we can feed repeatable signals to DFSDM for tests) - @TheBarrelShifter can likely provide more info on that.

We have 37.x prerelease builds available now - if you would like to test, just let us know. These builds also have the BTLE API in there and the dual-PWM DAC support.

If you want to use an ADC rather than a microphone then look for parts offering DSD output - We used the TI PCM4222EVM for our system test setup (mentioned by Hugo above), which is an evaluation board based on the following part

DSD provides a stream of sigma delta data which the DFSDM input on the imp004m can process into ADC values given the appropriate filter setup. I’m happy to help should you need any further information on how to proceed with either the connectivity or filter configuration.


ImpOS 38, including the new DFSDM support, is now available as a public beta. If you’d like to have your imps updated to try it out, please send a direct message with their IDs or MAC addresses.