How to record audio samples with STM32F7508-DK (via line in)

AKueh.1 · ‎2023-01-10

Hello,

I am wondering if it is possible to record the actual raw audio samples directly from the line in?

I tried to use the BSP example number three and stoped after recording the data. I recorded a sinus with 1 kHz. But when looking at the data most of them are 32768 and some few data are around 9000. Is this some kind of audio coding? Or what do I need to do, to see my acual sinus wave in my samples at this point?

Thanks!

AKueh.1 · ‎2023-01-11

Nevermind, the issue was that the ADC was totally overdriven. I used the wm8994 driver provided by the BSP example. And during the configuration of INPUT_DEVICE_INPUT_LINE_1 there was a +3dB gain for left and right channel. Of course, when using an microphone as input it could be okay - but when using an audio card as audio source I had to remove +30dB gain.

Now everything works as expected :)

View solution in original post

AKueh.1 · ‎2023-01-11

Nevermind, the issue was that the ADC was totally overdriven. I used the wm8994 driver provided by the BSP example. And during the configuration of INPUT_DEVICE_INPUT_LINE_1 there was a +3dB gain for left and right channel. Of course, when using an microphone as input it could be okay - but when using an audio card as audio source I had to remove +30dB gain.

Now everything works as expected :)