How to access the PDM Mic present in nRF5340 Audio DK board.

RE: How to access the PDM Mic present in nRF5340 Audio DK board.

laksh — Wed, 14 Aug 2024 05:47:27 GMT

Hi Maria,

Thanks, Let me check.

Best regards,

Lakshmanan

RE: How to access the PDM Mic present in nRF5340 Audio DK board.

Maria Gilje — Tue, 13 Aug 2024 13:46:21 GMT

Hi Laksh,

Today I found the NRF_I2S_SWIDTH_24BIT_IN32BIT sample width enumeration which looks promising. In this previous ticket they had a similar use-case to you as well.

See the I2S configuration used in the nRF5340 Audio applications here. Functions for initialising, starting, and stopping I2S are also found in the previous link.

Best regards,

Maria

RE: How to access the PDM Mic present in nRF5340 Audio DK board.

Maria Gilje — Fri, 09 Aug 2024 13:38:38 GMT

Hi Laksh,

I have been studying the datasheet for the SPH0645 microphone and found a possible hurdle. The microphone is 24 bit, and the nRF5340 audio application does not have support for that bit depth (only 16 and 32). I will ask internally for some guidance on this and get back to you by Tueday.

Thank you for your continued patience.

Best regards,

Maria

RE: How to access the PDM Mic present in nRF5340 Audio DK board.

laksh — Wed, 31 Jul 2024 05:15:52 GMT

Hi Maria,

Also, Can you help me with how to configure I2S and connect. Because in nRF Connect SDK Fundamentals they have given only for UART and I2C. It would be great If I get any reference material for that.

I'm Using nRF5340 Audio DK borad and trying to connect SPH0645 Mic with I2S. For brief info check this thread - devzone.nordicsemi.com/.../not-getting-i2s-data.

Thanks,
Laksh.

RE: How to access the PDM Mic present in nRF5340 Audio DK board.

Maria Gilje — Tue, 30 Jul 2024 13:59:59 GMT

Hi Laksh,

You can use this code block from encoder_thread() in nrf5340_audio/src/audio/audio_system.c as a reference for getting the PCM data.

I forgot to mention this last week, but since you are a newbie, you should look into our courses on DevAcademy. They cover both basics and intermediate topics and are also good reference material during development.

The courses which seems most relevant for you are:

nRF Connect SDK Fundamentals

Bluetooth Low Energy Fundamentals

nRF Connect SDK Intermediate

Best regards,

Maria

RE: How to access the PDM Mic present in nRF5340 Audio DK board.

laksh — Wed, 24 Jul 2024 11:11:46 GMT

Hi Maria,

I want a PCM data for sending.

RE: How to access the PDM Mic present in nRF5340 Audio DK board.

Maria Gilje — Wed, 24 Jul 2024 10:58:32 GMT

Hi Laksh,

[quote user=""] I also checked audio application example but I don't know how to set the project for BIS or CIS.[/quote]

This is documented in the documentation for the nRF5340 Audio applications, specifically in the section on configuring the nRF5340 Audio applications.

Considering that you want to use the PDM microphone the walkie-talkie demo seems like a good start. The walkie-talkie demo configuration of the nRF5340 Audio applications enables bidirectional CIS and uses the PDM microphones on both the headset and gateway devices. To use this configuration you just need to add CONFIG_WALKIE_TALKIE_DEMO=y to your preferred configuration file and build with your preferred method.

[quote user=""] It would be great if anyone guide me to access the mic and get the data.[/quote]

In the application, the PDM microphone is configured through the hardware codec CS47L63, so the relevant code is found in src/modules/hw_codec.c and hw_codec.h.

Which part of the process do you wish to get the data from? Before sending it or after receiving it?

Best regards,

Maria