Hardware considerations for an NRF5340 BLE Audio Application using the built-in PDM Peripheral with no audio codec - is it feasible?

[los45]

I am working with the NRF5340 to develop a BLE audio streaming application using a PDM MEMs microphone.

I have played around with the NRF5340 Audio DK and got PDM audio recording to an SD card (as a WAV file) using an external PDM microphone hooked up straight to the NRF5340 GPIO (bypassing the audio codec).

For the application, I am hoping to avoid using an additional audio codec and instead use the built-in PDM peripheral as the performance is suitable for my use case.

This is an educational project and I am on quite a tight schedule, so I am moving to hardware development before prototyping the full application/ embedded software on the NRF5340 Audio Development Kit. My eventual plan is to adapt the demo audio application to use the PDM driver I have written instead of the I2S driver and configure it as a headset.

I have a few questions relating to the hardware considerations for this use case as I want to avoid designing a PCB that simply won’t work. Mainly is it feasible to use the built-in PDM peripheral (with no external audio codec) while simultaneously streaming BLE audio?

At first glance, I believe both the PDM peripheral and BLE rely on the HFCLK, could this cause any issues?

Many thanks!

[Maria Gilje]

Hello,

Thank you for your patience.

I have a few questions relating to the hardware considerations for this use case as I want to avoid designing a PCB that simply won’t work. Mainly is it feasible to use the built-in PDM peripheral (with no external audio codec) while simultaneously streaming BLE audio?

It is possible to exclude a hardware codec from your design. But do note that the nRF5340 Audio application uses the hardware codec, so for your design you will need to modify the data flow.

At first glance, I believe both the PDM peripheral and BLE rely on the HFCLK, could this cause any issues?

I don't think that should be an issue, but I will have to double check.

This is an educational project and I am on quite a tight schedule,

Exactly how tight is your schedule? It could be useful for us to know in case your deadline is closing in.

Best regards,

Maria