nRF5340 Audio DK Transparency mode and external PDM

[Joao Colombari]

Hello guys,

I need to evaluate a couple of mics and some are digital and I2S mics. Im using the nRF5340 Audio DK, on which I can successively run the Audio App and the Walkie Talkie demo. The problem with the walkie talkie is the compression within audio path, so I want to record and play in the same board, as a transparency mode.

Is there any repo that's already implemented this with the Audio DK? 

About the external DMIC, I know I can use the Audio App with the internal MEMS and with the line in, which uses Cirrus codec to convert analog input to I2S. Can I use this port as a digital mic in??

Best regards!!

[Amanda Hsieh]

Hi, 

I want to record and play in the same board, as a transparency mode.

Is there any repo that's already implemented this with the Audio DK? 

This is the PR https://github.com/nrfconnect/sdk-nrf/pull/13299, but this is not merged into NCS for some reason. However, this can be a start. 

Can I use this port as a digital mic in??

Check this post. 

Regards,
Amanda H.

[Joao Colombari]

Hello, Amanda, 

I will take a look at the WAV repo. 

I have seen the Mic post and taken a good look at the HW connections on the DK, so its pretty clear that the line in is going to work only as a test input for analog amplified and buffered mics. 

Nevertheless, i've found P15 header (PDM2 referred with label HW_CODEC_PDM_2) and P11 header (Auxilary On-board HW CODEC interface which connects to HW_CODEC_AUX_i2S and I2C labels).

1 - Can I configure the audio app to use P15 header as input instead of  VM3011 mic? 

2 - Can I use AUX interface as inputs? 

Thanks for the quick reply,
Best regards!!

[Amanda Hsieh]

Hi, 

Joao Colombari said:

1 - Can I configure the audio app to use P15 header as input instead of  VM3011 mic? 

The team needs more time to investigate the solution. Next week is the Easter holiday in Norway, and the codec expert will return from vacation after Easter.  It might need to wait a little bit, or you can try to cut the trace and forward it to your PDM. 

Joao Colombari said:

2 - Can I use AUX interface as inputs?

You can reference the following code:

https://github.com/nrfconnect/sdk-nrf/blob/22fe3fcae951ece109b634f24d2d40fa07c563b1/applications/nrf5340_audio/src/modules/hw_codec.c#L314

Line 316 will use PDM as the audio interface; Line 322 will choose Line-In as the audio interface. 

-Amanda H.

[Joao Colombari]

Hello, Amanda,

Thanks for the tip. I was able to configure the inputs and to route them to the output with cs47l63_reg_conf header file. There is also the Cirrus Logic windows software that helps a lot on finding the registers you need to configure and routing the audio path.

I ran these changes within the Audio Application and got good results, so then I created a new application using only the files needed to communicate with and configure the CS74L63. I am facing some trouble with C compiler that some guys had a few years ago here in DevZone.

For the former problem, I'll wait for your reply and probably close this issue. For the second I'll open a new one. 

Happy easter for you guys, 
João.