Connecting 8 PDM microphones to STM32N6

[Tuomas95]

Is it possible to connect 8 PDM microphones to the STM32N6 via MDF?

[ELABI.1]

Hi @Tuomas95,

It is not possible to connect 8 PDM microphones directly to the STM32N6 via the MDF interface because the MDF has six digital serial interfaces. However, you can connect up to 8 PDM microphones by using the SAI peripheral's PDM interface.

This is mentioned in the Datasheet specifically section "3.48 Serial audio interface (SAI)", as shown in the screenshot below:

and also, in the Application Note AN5027 specifically section "2.2.3 Using PDM interfaces":

Thanks.

ELABI.1

 

 

[KDJEM.1]

Hello @Tuomas95;

 

According to this Solved: Re: NUCLEO-N657X0-Q: Confliciting info on number o... - STMicroelectronics Community and after checking internally, there are only three data IO: SAI_D1, SAI_D2, SAI_D3, in that case it will just support 3 pairs of microphones. It isn't possible to connect 8 PDM microphones by using the SAI.

Internal ticket number CDM0061647(This is an internal tracking number and is not accessible or usable by customers).  

Thank you

 

I apologize for any inconvenience.

Thank you.

Kaouthar

[Andrew Neil]

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@ELABI.1 wrote:

you can connect up to 8 PDM microphones by using the SAI peripheral's PDM interface.

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UPDATE: That post has since been edited.

 

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@KDJEM.1 wrote:

It isn't possible to connect 8 PDM microphones by using the SAI.

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So which is it, then ?

[KDJEM.1]

Hello @Andrew Neil ;

 

We noted a typo in datasheet and reference manual, the STM32N6 supports actually 6 microphones.

This issue is reported internally.

Internal ticket number CDM0061647(This is an internal tracking number and is not accessible or usable by customers). 

 

I apologize for any inconvenience.

Thank you.

Kaouthar

 

[Andrew Neil]

Ah, I see that @ELABI.1 has now edited the post to remove the references to the erroneous sections in the Datasheet (DS14791 Rev 9) and AN5027 (Rev 2), and the conclusion that 8 was possible.

 

PS:

It seems that RM0486 (Rev 3) also has the typo.