No audio from i.MX 8MIC-RPI-MX8 mic board on i.MX 8M MINI EVK

[knaing]

No audio from i.MX 8MIC-RPI-MX8 microphone array board on i.MX 8M MINI EVK.  I followed the procedure described in a quick start guide here https://www.nxp.com/docs/en/quick-reference-guide/IMX-8MIC-QSG.pdf .  Please advise. 

[knaing]

You could download design files for 8-MIC-PRI-MX8 here.

https://www.nxp.com/downloads/en/printed-circuit-boards/SCH-45632.zip 

I also found an easier way to work around this issue w/o having to remove the register.  Simply, remove/bend pin #7 of 40-pin connector.

[nxp31]

Hello Tom Zheng

the Link you have provided on 2020-03-04 is no longer valid. Could you please fix this?

Also I did not find the 8MIC-Board-Schematic.pdf on the product information page.

Do you know where to find it?

Do you know, which kernel drivers are involved in reading the microphones?

Is there any documentation on this?

Thank you very much.

Nest regards.

Volker Peters.

[haidong_zheng]

Hi a b:

You can find 8mic board schematic in nxp site: https://www.nxp.com/downloads/en/printed-circuit-boards/SCH-45632.zip 

I attached patch file in https://community.nxp.com/thread/526150?commentID=1278012#comment-1278012  which you may not access it. This patch is based on 4.14.78 release. 

mic driver is in sound/soc/fsl/imx-micfil.c

[knaing · Accepted solution]

For the time being, the problem was solved after removing the resistor R24 (on Pin 4 of Raspi 40-pin Header connected to MIC_MUTE_INT on U11 of MUTE SWITCH).  We found that MIC_MUTE_INT connected to UART3 on  i,MX 8M Mini EVK is always high, effectively overriding the MIC MUTE switch state.   Proper way to solve this issue may be by pulling down the UART3 pin on EVK.  Please post here if you find a better way to solve this problem.

Refer to 8MIC-RPI-MX8 Product Information|NXP  8MIC-Board-Scemetic.pdf for more details.

[kedon]

This hardware patch worked for me too! Thanks!

[haidong_zheng]

Hi Kyaw:

You can refer to https://community.nxp.com/message/1278012?commentID=1278012#comment-1278012  to get as SW way to solve  this. 

[AndyNien]

hI, 

I am looking for SW solution of  8MIC-RPI-MX8. Can you  give me a hand?