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Confusion with MDF and its SPI/Manchester setting

Bastien LS
Associate III

Hi all,

We are trying to wire a microphone to the STM32U585. The microphone (T5838) outputs PDM and takes a clock as input.

As far as I understand, the MDF peripheral supports PDM interface (as stated in RM046, Rev 4, 39.1), so it is compatible with the microphone.

The PDM output should be wired to MDF_SDIx, and we can the provide the clock for the microphone with MDF_CCKy.

BUT, later in the documents, it is stated that:
```
The SITFx input interfaces allow the connection of the external sensors to the digital filters,
via the bitstream matrix (BSMX). The SITFx serial interface can be configured in the
following modes:
• LF_MASTER SPI mode (low-frequency)
• normal SPI mode
• Manchester mode
```

To me, SPI is a protocole used to communicate data, just as Manchester, and it is nothing like PDM.
What are these "modes" and what is their use?
Can I use the MDF to communicate with an external ADC through a SPI bus? Can't I use the MDF to read PDM?

I spent hours reading the documentations and I still can't figure out what SPI/Manchester does here, what mode I should be using, and if the microphone is even compatible with the MDF.

Best regards
BastienLS

1 ACCEPTED SOLUTION

Accepted Solutions
Issamos
Lead II

To interface PDM with STM32, I suggest you to take a look at the AN5027.

Best regards.

II

View solution in original post

3 REPLIES 3
Issamos
Lead II

To interface PDM with STM32, I suggest you to take a look at the AN5027.

Best regards.

II

When your question is answered. Select a best answer to close the topic.

Best regards.

II

Bastien LS
Associate III

Yes, this really helped. Thank you.