PDM microphone(s) configuration issue

Hello RGr,

RGr said:
It seems my BCLK IN2 pin gets GEN1 3.072 MHz clock signal no matter what are the settings for Serial port 2 OUTPUT/INPUT settings

You are getting 3.072MHz since the core and serial port are run at 48KHz and serial port is set for I2S inputs with 32 bits per channel. If you change the core rate or serial port rate or data format, then you can see the BCLK changes but there is no need for that. Let it be this way. This is the usual setting for PDM mic interface with nominal sample rate and channels. You can refer PDM section of the datasheet for required clock frequency and other details.

RGr said:
if I use BCLK IN2 then SERIAL INPUT PORT SDATA_IN2 is to be configured?

It's not mandatory to use that port to transfer any data (by using SDATA_IN2) in order to use BCLK pin of that port. The thing is you will be getting BCLK and LRCLK's clocks in all four serial input and output ports once you link compile download the project (By default all ports are set as clock masters). You can just take any port's Bit clock as a reference for your PDM mic. so, it's not necessary to use that port for data transfer in order to use the pin as a reference.

All you have to do is to pick any port's BCLK and configure it in the DIGITAL_MIC register setting and also the same for the MP pins.

Kindly do reply if you have further queries.

Regards,

Harish

Thank you for your assistance!

How can I attach my .dspproj file to my post, so perhaps someone could suggest where the problem with my setting is?

I do appreciate your answer, but it is not really directing my to fix the issue - second mic is not working.

Hello RGr,

I didn't realize that you were facing issues with your second mic since you didn't mention it in your previous post. Please attach your project we will have a look and assist you further.

To attach a project, one way of doing this is to just drag your project and drop it in the comment box or click insert (below the comment box) >> Image/video/file >>upload >> choose the project and select ok.

Regards,

Harish

Please have a look at the attached .dspproj file with my experiments. The tone generator and sum blocks were added for test purposes only, so I can easily verify the outputs work, and that my hardware is connected and operational. This way I expect to hear both mics on both L/R speakers.

hm, I get "File type is not allowed: sine777r4.dspproj" message, both ways drag&drop and via insert menu

Hello RGr,

I apologize for the trouble. It seems like an issue with the forum.

However, you can zip your project and send as a zip file. It is allowing to post a zip file.

Regards,

Harish

Hello Harish,

if this is the official recommendation then I zipped it and attached, and it seems to be possible now.

I did not do it before, as I think I have seen project files posted here unzipped.

Please have a look at the attached .dspproj file with my experiments. The tone generator and sum blocks were added for test purposes only, so I can easily verify the outputs work, and that my hardware is connected and operational. This way I expect to hear both mics on both L/R speakers.

Thank you again for your responses and support.

sine777r4.zip

Hello RGr,

Sorry for the delay in response.

The project attached below is set for 4 PDM mics and it's working fine with all registers are already set. I give BCLK_OUT1 as a clock reference. All you have to do is to connect your Mic with respective pins of the board and choose any BCLK as you wish (I choose BCLK_OUT1) and set it in the register of Digital Mic tab.

No modification is needed in the project if you are using the same Mp pins and BCLK as I did. Just run the project 'as is' with correct external hardware connections.

sine777r4 (modify).zip

Kindly do reply if you still have problem.

Regards,

Harish

Hello

Quick update. Right around the time of your post I also noticed I could no longer drag and drop in project files. It was not allowing the file extension type. So I reported it to the programming team for the forum and they had accidentally removed that functionality with a recent update. It took a day and they restored the ability to just drag and drop *.dspproj files into a post without having to zip it.

In the future you should not have to take that step. Sorry for the hassle.

Dave T