STM32H747I-DISCO, codec outputs noise in BSP example.

[Nida]

Hello,

I built and uploaded the BSP example from the H7 MCU package, version 1.12.1, on my STM32H747I-DISCO board. I tried the various demos included in the example and they work but it seems there is an issue with the codec configuration.

(I didn't change anything)

While testing the analog_audio_record demo (which should record from the input jack and pass the recorded data to the output jack) i plugged in my headphones in the output jack and noticed that there is a lot of noise, regardless of if an input jack is connected or not.

Playing a song on max volume from the input jack I could hear it above the noise.

While testing the audio_record demo, the microphone was less affected by noise but has a large gain.

I stumbled upon this video on youtube: https://youtu.be/O2XaCFsWxSw?si=J-KL4CMG7EA3le86
"STM32F7 Discovery : Audio Line-in to Line-out Pass-through" from "PizzaBear Engineering".
He points out how some register writes may be inappropriate, like 0x0035 to registers 0x29 and 0x2A, seting up a 30dB gain (in min 11:16). I tried to change this value to 0x0020 like in the video to see if it was the cause of the noise, but all it did was making the noise and the signal quieter and I can't hear anything but an hiss now.

I tried studying the datasheet of the wm8994 but coudn't understand how to make it work, I just understood what it could do. I am not an experienced user so I would like to use some sort of BSP function instead of spending a lot of time trying to learn to configure it.

Is there another example that I can try?

Is there something in the configuration that needs to be changed?

[AScha.3]

Hi,

first some things to think about:

- did you read the WM8994 ds ? or at least, look at it ? It has 359 pages, about 300 or 500 registers (!!OMG!).

- to understand it in a basic way, needs many hours - to more or fully understand it, maybe some 2 or 3 weeks.

- What you want to do with it - really ? 

see start of ds :

A lot of programming and understanding of most or all internal modules is needed...

or you want just play a demo, to see: ok, its doing something ?

->  instead of spending a lot of time trying to learn to configure it.

So decision is : you have got it "doing something" , ok, and now play with something else, 

OR read and learn , until its doing exactly, what you want - even you might need 2 weeks or more to do this demanding job.