DMIC: plans for STM32 DFSDM support

[facchinm]

Hi all,
as Arduino we are interested in supporting digital PDM microphones (like the ones that can be found in Nicla Vision and Giga Display shield). @erwango do you have this task in your roadmap and/or is there any ground for collaboration 🙂 ?
@maidnl

[erwango]

Hi @facchinm !

We don't have plans atm, but we'd be please to collaborate. I can't promise anything on the bandwidth we'll be able to allocate though since we'll have a quite busy year 2026, but we can see if/how it can be arranged.
What would be your timeline ?

[facchinm]

The ETA is a very generic "2026" so there's a bit of time 🙂 . In the meantime, if someone from the community is interested too, please reply to this thread so we can coordinate!

[rgallaispou]

Hi @facchinm,

I am working on DFSDM driver (which is available on F4, F7, H7, L4, L5, MP13 and MP15).
I plan to implement MDF (H5, H7RS, MP2, N6, U3, U5) after that. On which SoC to you need the DMIC support ?

Regards

[maidnl]

Hi @rgallaispou ,

From your message I cannot guess if you already have developed a DFSDM driver or if you are listing the micro on which the DFSDM is present... anyway we (@pillo79 and I) checked the last zephyr version and PRs and we did not find anything related to DFSDM driver, so maybe you just started working on that...

If that is the case I have already implemented a driver for DFSDM which is working on H7 microcontroller (the main reason for this development is that we use DFSDM on Arduino Giga with a PDM microphone present on Arduino Giga Display).

The driver works but has some problems (related to the possibility to push it mainline):

• the driver is probably too "focused" on H7 DFSDM peripheral, it implements, for example, also "details" like watchdog functions (which I don't know is a function available on every DFSDM)
• the driver defines almost all as configuration parameters while probably some of these parameters are better to be coded at Device Tree level
• the driver uses DMA but the use of DMA is optional and applicable from device tree selection, but the code still require in that case that DMA is available at configuration level
• examples re-defines the DFSDM in the device tree overlay
• the DFSDM is defined in the device tree at the board level while it should be defined at the soc one

maybe you'll spot some other problems.

Anyway you can find my flawed implementation here (all is in a single commit): maidnl@0fc8af4

If you have just started maybe some of this could be used and/or (if you want, of course) I could be available to cooperate for the mainline driver development. Let me know your thoughts about that.

Our main and minimal goal is to have DFSDM driver available on H7 (Arduino Giga board) for PDM microphone application.

Thank you and have a nice day
Daniele

@pennam

[rgallaispou]

Hi @maidnl,

Yes, I have indeed started to implement the DFSDM, here's my version. I planned to do a PR in the days that are coming.

Can I suggest a collaboration ? Maybe I can do an initial PR so that discussions can emerge from this ?

[maidnl]

Thank you @rgallaispou.

Let's follow your plan.

I'll wait for your PR (if you can, please tag me here or in the PR so that I know is out there).
In the same time I will have a look at your version and I will try to play a little bit with it.