PCMD3140: Can't stream audio from 4 PDM microphones

Tsugumi Murata

Prodigy 250 points

Part Number: PCMD3140

Hello,

I am currently testing the PCMD3140 using the PCMD3140EVM.

I have 4 external microphones (Invensense T5818) that I am trying to stream audio from.

I am using the PPC3 (V3.2.1) with the following config (4_MIN_CONFIG).

Using this config file, I am not able to stream audio data from 4 microphones.

I can stream the audio data for up to two microphones, and these are the ones that the mics allocated in the Left-Slot 0 and Right-Slot 0. For the image attached, Channel 1 and channel 3 works but 2 and 4 doesn't respond. This is not microphone dependent and as long as the microphones are attached to the Left-Slot 0 or Right-slot 0 it will work .

4_MIC_CONFIG.zip

I did capture the I2S lines using 4 microphones (CH1 :BCLK, CH2: FSYNC, CH3: SDOUT), and seems like the data bits are properly being sent, I just can't hear the audio.

Do you have any idea of what is happening here?

Sincerely ,

Tsugumi

over 3 years ago

0 Arthur Brown over 3 years ago

TI__Mastermind 21195 points

Hi Tsugumi-san,

The data does appear to be correct on the SDOUT.

How is your I2S reciever configured? Is your I2S receiver expecting 2 channel I2S? the receiver could be not expecting 4 channels of data

Regards,

Arthur

0 Tsugumi Murata over 3 years ago in reply to Arthur Brown

Prodigy 250 points

Hello Arthur,

I do have all 4ch active, also here is the PPC3 config file I am using to test. 3073.4_MIC_CONFIG.zip

Do you see any issues with the config setting I am using / could you provide config file for 4 PDM output ?

0 Arthur Brown over 3 years ago in reply to Tsugumi Murata

TI__Mastermind 21195 points

Hi Tsugumi,

I will look into the configuration and get back to you

Regards,

Arthur

0 Tsugumi Murata over 3 years ago in reply to Arthur Brown

Prodigy 250 points

Hello Arthur,

Any update on this item?

Sincerely,

Tsugumi

0 Arthur Brown over 3 years ago in reply to Tsugumi Murata

TI__Mastermind 21195 points

Hi Tsugumi,

I could not find an EVM, I have an EVM on order. it should arrive early next week. I will provide the configuration next week.

Regards,

Arthur

0 Tsugumi Murata over 3 years ago in reply to Arthur Brown

Prodigy 250 points

Hello Arthur,

Any update on this item?

0 Arthur Brown over 3 years ago in reply to Tsugumi Murata

TI__Mastermind 21195 points

Hello, Tsugumi,

I have been very busy with another project these past 2 weeks. I will provide the configuration before the end of this week

Regards,

Arthur

0 Jeff McPherson over 3 years ago in reply to Arthur Brown

TI__Mastermind 48515 points

Hi Tsugumi,

I am taking over this thread as it never got solved. I can look at your configuration tomorrow, but I wanted to ask why i2S is necessary. Typically i2S doesn't support more than 2 channels. TDM mode does, and will also support a 50% duty cycle.

Best Regards,

Jeff

0 Tsugumi Murata over 3 years ago in reply to Jeff McPherson

Prodigy 250 points

Hello Jeff,

Sounds good, please do let me know.

This chip allows up to 4 PDM microphone data over I2S, and that is the reason why we are using this chip.

If you look at the I2S waveform I attached to the first post, you can see all 4 mic data showing up. The issue I have is that I am not able to hear the audio data from all 4 microphones when recording it using my computer audio application.

Thank you for your help in advance,

Tsugumi

0 Jeff McPherson over 3 years ago in reply to Tsugumi Murata

TI__Mastermind 48515 points

Hi Tsugumi,

I recently evaluated this part, and have gotten it to work with multiple PDM mics. As you also see, the data is present so something is misconfigured on your receiver end, which makes it harder to support. Which application are you using to record from the EVM?

Best Regards,

Jeff

0 Tsugumi Murata over 3 years ago in reply to Jeff McPherson

Prodigy 250 points

Hello Jeff,

Were you able to stream audio from 4 PDM microphones? If possible can you send that config file so I can test it out as well?

Right now I am just using the voice recorder app on windows.

Sincerely,

Tsugumi

0 Jeff McPherson over 3 years ago in reply to Tsugumi Murata

TI__Mastermind 48515 points

https://e2e.ti.com/cfs-file/__key/communityserver-discussions-components-files/6/4PDMw2Analog_5F00_ADC3140.ppc3

Hi Tsugumi,

Try this file. It's currently set up for 2 PDM inputs (4 channels) and 2 Analog inputs but it should work for your case. If the part is correctly outputting data I can't give much more support since it seems the issue is with how you are receiving the data, not with the converter itself. A stock app like the Windows Voice Recorder may not be equipped to decode PDM mic channels properly and is ignoring the other channels.

Best Regards,

Jeff

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PCMD3140: Can't stream audio from 4 PDM microphones