Forums - [MDM9607] I2S Communication Stereo problem- alsa lib

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[MDM9607] I2S Communication Stereo problem- alsa lib
pietrospeciale
Join Date: 19 Jan 21
Posts: 3
Posted: Thu, 2021-02-11 08:13

Hello to everyone,

I would like to use a maxim 9867 codec to communicate via I2S, with PCM protocol in TDM mode with the mdm9607, in stereo mode. 

The problem encountered, however, is that the qualcomm only reads the left channel; although the MAX9867 supports 2 separate channels (LEFT/RIGHT)  in my testing the recording of the 2 channels results in a stereo track with the left channel copied to the right. 
 
Below please find additional details about our application.

CODEC
Codec in Slave mode, PCM, Burst (TDM) Mode
 
MDM9607
Master Mode, 
AT#DVICFG=1,1,2,1,2
AT#DVI=1,2,1
DVIEXT=0,0,0,0,0

Also, referring to the integrated ALSA library, I would like to understand if it is possible to change the audio paths.

 At present I can only use:

Record an active voice call (analog audio) :
 
amix 'MultiMedia1 Mixer AUX_PCM_MAX9867_UL_TX' 1 
amix 'Input Mixer' 1 
arec -D hw:0,0 -R 16000 -C 2 file.wav 
 
or :

Record an active voice call (digital audio): 
amix 'MultiMedia1 Mixer AUX_PCM_UL_TX' 1 
arec -D hw:0,0 -R 16000 -C 2 file.wav

Obtaining a 16K .wav file, with 2 equal channels.

But I have seen that with amix, I could give many other configurations (audio paths), as long as they are activated, and I would like to understand if I can use one to use DVI as audio data (nov voice call), so that I can read the 2 stereo channels.

Looking forward for your feedback
 
Best Regards


 
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pietrospeciale
Join Date: 19 Jan 21
Posts: 3
Posted: Tue, 2021-02-23 07:46

Hello to everyone,

the qualcomm device is an mdm9207 ( the kernel used is the one related to mdm9607 ).

At this link:

https://developer.qualcomm.com/hardware/mdm9207-startup-kit

I read:

The MDM9207 IoT Modem startup kit includes links to all necessary files with full instructions for flashing, compilation and device setup. Demo programs cover "Hello World," peripherals and connectivity. Developers can adapt the sample code to their own applications.

But the link to github is broken.

Where can I find the repository for the mdm9207 startup kit?

Looking forward for your feedback

Best Regards
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jddennis
Join Date: 27 May 15
Posts: 245
Posted: Tue, 2021-02-23 13:00
Apologies for the inconvenience. We are working on making that link available for everyone, but it will take a little time to get it setup. I removed the link for now.
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pietrospeciale
Join Date: 19 Jan 21
Posts: 3
Posted: Thu, 2021-02-25 00:30

Thanks for the quick reply JD Dennis,

I am waiting for the startup kit link to understand if it is possible to modify some of the libraries present in the MDM9207 kernel.

I want to describe my problem:

We are currently designing a system based on your MDM9207 processor that captures stereo audio from 2 microphones and can send it over the network.

The codec used is the max9867 which can communicate with the mdm9207 via I2S / PCM. The codec can send the left and right channels through the aforementioned protocols, but the library integrated in the kernel reads only the left channel (mono), or copying it to the right channel (dual mono).

The device under testing was taken through the Telit distributor (LE910C1 device). The kernel is limited in permissions, we cannot load any additional libraries or modify existing ones. We opened a ticket with Telit, who informed us that it is impossible to make the change as the kernel is managed by Qualcomm.

I would like to understand if this limitation (purely software) can be solved through the SDK, or if there is already a kernel version that supports I2S / PCM communication in stereo. Thanks for any information / help you can give us.

Best Regards

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jddennis
Join Date: 27 May 15
Posts: 245
Posted: Thu, 2021-02-25 08:51
I checked with the product team, and they indicated the startup kit we are supporting is based on the EC25 Quectel Module and the Quectel SDK/Tools. So any requests for support for kernel modifications/changes/additions will have to be with Quectel directly.
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