STM32 Audio Recorder 1: STM32 I2S DMA || SPH0645LM4H MIC

[@steppeschool3629]

Just to remind you that the source code of this project is available on Github: github.com/Steppeschool/STM32-Audio-recording-.git

[@batosato]

Thank you for the video and a great tutorial. If you don't want to remove the microphone from the board then switch to I2S3 instead and follow the tutorial. The recordings will be done without any hassle :)

[@steppeschool3629]

Thanks for the info!

[@Марш-ц6ф]

Friend, thanks for the video. Can you send or take a video, which contacts did you connect the microphones and SD card reader to?

[@lucadebs7872]

Why at 10:44 did you write sample_i2s = data_i2s[0] ? You are saving in sample_i2s every time the first of the 100 samples contained/stored in data_i2s ... why ? Then in SWV data trace Graph you display sample_i2s, but shouldn't you display data_i2s ?

[@steppeschool3629]

Hi, This step is necessary to verify that we are getting data from the microphone. Since data_i2s is a buffer, we cannot plot it using SWV. That is why I plot only the first element of the buffer.

[@exprymer]

Hello, i saw that you sacrificed the bits last 2 bits for simplicity. how can i retrive the value in Pa (float) using this data?

[@VigneshVicky-en3tl]

I have to interface STM32F407 with PDM digital mems microphone to Capture the realtime sound waves through I2S Serial communication.But little bit confusion is there because in I2S communication there are three pin Datapin,Clk pin and word select pin(WS).But in my PDM microphone Vdd ,Gnd,L/R,Clk only there,No WS pin there in my microphone.So,How to I configure ?

[@electro.engineering]

It seems like a great course. I was checking my board (STM32H757I-EVAL) and I have a lot of periphs on it, but I don't have an embedded mic. D*mn it😂. I never tried 0.1% of all it can do. I'm a beginner when it comes to this ecosystem and this board. I read on the datasheet that it even has 1x Digital Filters for Sigma Delta Modulator with 8 channels/4 filters. The thing can do my entire 2 classes on Signal Processing 😂 (I'm an Electrical Engineering Student)

[@steppeschool3629]

Yes you are right😀. Modern microcontrollers are quite powerful and can do many things. I suggest you to start from basics and move to advanced staff. Basically, divide and conquer strategy. Personally, I would be happy to share with you my knowledge. You can sign up my courses and follow the lessons.

[@electro.engineering]

@@steppeschool3629, after reading more through the documentation, I saw that I actually have: headset and speaker connectors, for an analog mic and analog output, of course, and 2 other connectors for ST-MEMS Digital Microphones. It looks like it's all there already haha; sure, I'll take a look.

[@lucadebs7872]

Why you use at 5:21 "16 bits data"?? The mic has a data format of 24 bits and 18 of them are data. There's written in the file you showed at the beginning of the video. Shouldn't you use the "24 bits data on 32 frames" option?

[@steppeschool3629]

Yes, you can do that, but you have to do some bitwise manipulations to save 24-bit frames of data to the SD card. However, I 'sacrificed' 2 bits (18 - 16) for the sake of simplicity and having less amount of data. There is little difference between 18-bit and 16-bit precision. Did I answer your question?

[@lucadebs7872]

@@steppeschool3629 Thank you for your reply! If I wanted to keep 18 bits (by selecting '24 bits data on 32 bits frame'), what manipulation should I do? Do you have any website/video/tutorial to recommend me that talks about this? If this operation has a specific name, I'll look it up online.

[@steppeschool3629]

The simplest way to preserve 18 bits would be to store all 32 bits. However, you have to store two times more data, and 14 (32-18) low-significant bits will be just zeros.