PDM2PCM example code

[kcire L.]

Hello,

I am trying to understand the PDM2PCM conversion using I2S as the receiving protocol. Does anyone have an easy example for generating a single PCM sample from the PDM data bits? I am having some difficulty doing this using the VM3000 PDM MEMS microphone.

Any help would really be appreciated.

Thanks

[Imen.D]

Hello @kcire L.​ ,

Which STM32 are using ?

Have a look at these resources, it may helpful for you depending to your needs.

• UM2372 User manual STM32Cube PDM2PCM software library for the STM32F4/F7/H7 Series.

The performances for PDM2PCM library and the Frequency required depends on the configuration of many factors : sampling Freq, resolution etc.

The UM2372 provides resources requirements for memories and frequency for a PCM sample rate and detailed the parameters for the configuration of the library.

• AN5027 Application note Interfacing PDM digital microphones using STM32 MCUs and MPUs
• AN3998 Application note PDM audio software decoding on STM32 microcontrollers

Hope this helps you :smiling_face_with_smiling_eyes:!

Imen

[kcire L.]

Hi Yes, I have seen those resources you posted. I am using the NUCLEO-F401RE.

Any ideas on how to convert a single sample for each PDM_Filter() call?

Thanks

[Imen.D]

I am checking if there is a PDM2PCM example

I will try to contact expert internally for helping and I will come back to you with details.

Imen

[kcire L.]

Thanks very much! I look forward to hearing back from you.

[Imen.D]

Hi @kcire L.​ ,

Sorry for my late reply, but I've found it difficult to come back to you as the expert was on leave.

and I just received a response from him that unfortunately there is no such example available.

Imen