Which MCUs have SAI with PDM interface, as suggested by AN5027?

[falling_in2_infinity]

I'm trying to implement a 6- or 8-microphone arrangement, as outlined in AN5027 (p25). The recommended approach is to use an SAI with PDM interface, but I'm struggling to find a suitable MCU (and subsequently, a suitable Nucleo dev board).

I've not even seen an actual working example of this, but I'm assuming I'd configure the PDM as a mode in the SAI configuration. What I know for sure is that when I configure the SAI on my L4A6ZG, there is no option for PDM mode.

I'd welcome any advice.

Thanks!

[Walid ZRELLI]

Hello @falling_in2_infinity​ ,

We provide many examples that use an SAI with a PDM interface.

You can refer to the following examples provided under the H7 Firmware Package:

• Path: Firmware\Projects\STM32H743I-EVAL\Examples\BSP
• Path: Firmware\Projects\STM32H735G-DK\Examples\BSP
• Path: Firmware\Projects\STM32H743I-EVAL\Examples\SAI\SAI_AudioPlayback

I hope this helps.

BeST Regards,

Walid

[falling_in2_infinity]

Thanks Walid,

That's great, thanks! So other than the H7, which other MCUs have a PDM interface? Is there a simple way to find products with a given interface? The product selector page doesn't seem to allow this level of filtering.

Thanks,

...Joe.

[waclawek.jan]

Have a look at 'G4, the L4+ (i.e. the higher-end L4 with letters in the numbering), and maybe 'L5/'U5?

We are begging ST for ages to produce a comprehensive overview of modules' versions across the various families.

JW

[Walid ZRELLI]

Hello @falling_in2_infinity​ 

Take a look at the following MCUs which have a PDM interface: F2/F4/F7/H7/WB

BeST Regards,

Walid

[falling_in2_infinity]

Thanks JW. I'll check these out.

I join your campain to ST... it's very strange not to have such an overview. I would not even mind if more features were searchable in the product finder.

...Joe.

[waclawek.jan]

Hi @Walid ZRELLI​ ,

There is no SAI in 'F2 and only in some 'F4; and even in those that's the older version of SAI which has no PDM mode.

Of course PDM is just a plain bit stream and one can always use SPI/I2S which is available on every STM32, to connect one PDM source/microphone (i.e. not the "stereo" both-edges configuration) per SPI/I2S module.

JW

[Walid ZRELLI]

Yes, you are right @Community member​ there is no SAI for F2. Thanks for correcting me.