Integration of PDM microphone with thingy53

[Rakshita]

I want to integrate the PDM microphone with thingy53, I found no particular sample code for it

Would be needing help from scratch

[ovrebekk]

Hi Rakshita

Have you tested the DMIC sample in the SDK?

It is not officially supported on the Thingy53, but it does support the nRF5340DK. If you copy and rename the nrf5340dk_nrf5340_cpuapp.overlay file to thingy53_nrf5340_cpuapp.overlay, and change the pins as necessary, I would expect the example to work on the thingy as well. 

Not sure what you mean about repeating output? If I understand you correctly the clock output from the nRF53 is fine, but the data from the microphone seems wrong? Would you be able to attach a trace/scope capture? 

Best regards
Torbjørn

[Rakshita]

dmic is not working with thingy53 even after changing the overlay files 

[Rakshita]

No issues
If u say I can send u the code on which I was trying to enable microphone

[ovrebekk]

Hi Rakshita

Sure, please share your code. I will take a look at that before attempting to create a new example. 

Best regards
Torbjørn

[Rakshita]

Can u tell me how to attach a zip file

[Rakshita]

I went through the snoring example and added the necessary files into my code so right now getting the attached below result

[Rakshita]

[00:00:03.110,351] <inf> NRFX_PDM: Function: nrfx_pdm_start, error code: NRFX_SUCCESS.
TRUE 
  17,    b,    7,    b,   14, ffe9,   2c,    6, 
ffc0,    8,   49,   1d,   36,   5d,    6, ffc8, 
[00:00:04.111,877] <inf> NRFX_PDM: Function: nrfx_pdm_start, error code: NRFX_SUCCESS.
TRUE 
  24,   18,    5,    1,    4,   18,   21,   1a, 
   3,    5,    3,    5,    e,   13,    a,   10, 
[00:00:05.113,494] <inf> NRFX_PDM: Function: nrfx_pdm_start, error code: NRFX_SUCCESS.
TRUE 
  53,   2a,   2e,   1d,    b, ffed, ffdd, ffd8, 
   9, fffe, fffe,    8, fffe,    9,    5, ffff, 
[00:00:06.115,020] <inf> NRFX_PDM: Function: nrfx_pdm_start, error code: NRFX_SUCCESS.
TRUE 
   b,    9,    f,   36,   4f,   44,   3b,   15, 
  1c,   1d,   14,    e,    6,    7, fffa,    2, 
[00:00:07.116,607] <inf> NRFX_PDM: Function: nrfx_pdm_start, error code: NRFX_SUCCESS.
TRUE 
ffda, ffd1, ffdd, ffb4, ff98, ffad, ffde, ffc3, 
   6,   25,   34,   21,   12, fff2, ffdb, ffcf, 
[00:00:08.118,164] <inf> NRFX_PDM: Function: nrfx_pdm_start, error code: NRFX_SUCCESS.
TRUE 
ffc0, ffd5,    3,   13,   2c,   1d,   15,   10, 
ffb6, ffa0, ffbb, ffcb, ffbc, ffc0, ffd2, ffbb, 
[00:00:09.119,750] <inf> NRFX_PDM: Function: nrfx_pdm_start, error code: NRFX_SUCCESS.
TRUE

[ovrebekk]

Hi 

Rakshita said:

Can u tell me how to attach a zip file

You can just drag drop a file into the reply window. Alternatively you can click on Insert -> Image/Video/File

Rakshita said:

I went through the snoring example and added the necessary files into my code so right now getting the attached below result

This looks like real audio data to me, just very low amplitude. You would expect values that oscillate between positive and negative values, like in your log. 

I also did a quick test changing my modified dmic sample to use the proper PDM pins, and I seem to get valid audio data as well (but I haven't verified this properly by playing the audio back). 

Best regards
Torbjørn

[Rakshita]

So should I change the gain value?

[Rakshita]

0456.microphone.zip

[Rakshita]

And what about this 
RMS value: 43.991271
RMS value: 54.246826
RMS value: 75.447407
RMS value: 97.405862
RMS value: 99.503123
RMS value: 99.571268
RMS value: 478.356399
RMS value: 492.462257
RMS value: 501.362197
RMS value: 502.130812
RMS value: 491.400654
RMS value: 473.611738

[Rakshita]

If some sound is also detected there should be a threshold value right to compare so how is that decided