Hi , I like to use NUCLEO-L476RG's DAC output to output audio from analog and digital microphones. Can I stack both AMICAM1 and CCA02M2 modules on Nucleo-L476RG at the same time?

[WDai]

Which board should supply the power to the system?

I am using AMICAM1 to power the NUCLEO-L476RG following the instruction. AVDD is provided by AMICAM1 because the SB57 on NUCLEO-L476RG has been removed. Will a powered AMICAM1 module also supply power to CCA02M2?

Can both analog and digital mic modules be connected to PC through the onboard USBs at the same time?

Any conflicts in connector pins?

[Eleon BORLINI]

Hi @WDai​ ,

checking both schematics for X-NUCLEO-AMICAM1 and X-NUCLEO-CCA02M2 boards, I'm afraid that you cannot plug them together, or at least you cannot acquire the Analog microphones and the Digital microphones at the same time, since they might share some morpho connector pins.

You might however try to synchronize the different acquisitions in different time slots.

-Eleon

[WDai]

Thanks a lot Eleon.

Looking at the diagrams, analog mic signals are through connector CN7 and digital mic signals are using CN10.

If I connect only one module to USB (for example, AMICAM1), I could use its E5V to power all three modules (L476RG, AMICAM1 and CCA02M2), i think the 3.3V is from the L476RG board. VREF for DAC is from AMICAM1.

It may be possible to acquire both analog and digital mic outputs, only route one pair to the DAC as well as to the USB (for sending data to PC).

Your thoughts?

[Eleon BORLINI]

Could be @WDai​ ... Honestly, I never tried to plug them together and run acquisitions (more for the implementation of a proper firmware project than for other reasons), but it may be possible if no hard conflicts appear, after all...

The limitation to be checked at firmware level for the "parallel" processing of several analog and digital microphone together, but the 3.3V for Vdd is ok for all the microphone.

-Eleon

[WDai]

I was able to make the AMICAM1 work with the following settings:

1. AMICAM1, CCA02M2 and L476RG stacked together.
2. CCA02M2 connected to PC via USB. This USB provides 5V to the system through E5V, also streams data to Audacity on PC for recording. (default SB settings)
3. STLINK of L476RG is connected to PC. JP5 set to E5V. SB57 open.
4. USB on AMICAM1 is not connected.
5. Run microphone streaming example of AMICAM1 for L476RG,
6. Use Audacity to record the data. Data path = AMICAM1 -> NUCLEO-L476RG -> CCA02M2 USB -> PC

I cannot make CCA02M2 work immediately, because:

1. The mic streaming example of CCA02M2 for L476RG is using the DFSDM interface.
2. The default settings of the SBs on CCA02M2 are for I2S interface using SPI and Timer, these settings support the example for F401RE board.
3. Need to port the example from F401RE to L476RG first, before testing again

Make sense?

WW

[Eleon BORLINI]

Hi @WDai​ ,

some time to come back to you but that should work...

So, if I well understand, your purpose is to stream all the 4xAnalog MICs with the 4xDigital MICs with the via USB, not necessarily in simultaneity, right?

The default data flow is, as you know, from X-NUCLEO-AMICAM1 to host PC via USB, but you can decide to route the data stream back to the L476RG STM32 and merge it with the digital data coming from the CCA02M2... Not an easy job, but the synchronicity is not mandatory for you, it should be theoretically feasible.

-Eleon

[WDai]

Hi Eleon, my goals for now is are

(1) route Analog mic signals from AMICAM1 or Digital mic signals from CCA02M2 to the DAC in the NUCLEO-L476RG. They don't have to be routed simultaneously.

(2) the 3 boards, NUCLEO-L476RG, AMICAM2, CCA02M2, all stacked together. AMICAM2 and CCA02M2 having default SB settings. SB57 of NUCLEO-L476RG removed so Vref supplied from AMICAM2.

I can use L476RG's SPI2 and TIM3 to get PDM bit stream (stereo) from the digital mics on CCA02M2 into L476 now. The focus now is to demultiplexe the stereo bit stream and convert PDM to PCM. I noticed there is no example of this PDM2PCM conversion for STM32L4xx, only available some examples for STM32F4xx boards.

1. Do you know if ST has such routines for STM32L4xx?
2. Can you point me to some reference about porting code from one platform (example, F4) to another (L4)?

WW