Help needed - Teensy 4.0 + Audio Shield = Noise when SD Card write

[Natur]

Hi,

I'm making the project "Audio Guessbook" from this tutorial:

I'm using a Teensy 4.0 with an Audio Shield similar to the tutorial.

Everything work fine exept: a noise coming from the function "frec.write(buffer, sizeof buffer);" when recording a message.

Look like the noise is synchro to the led of the Teensy 4.0 just below the SD Card.

Here what I've checked so far:

- wiring look ok, visually checked multiple time
- no error in code
- used different power supply (from mac & normal plug)
- used a ground isolator
- tested 3 differents mic
- used different card sd (32gb can't write on it but can read - 16gb doesn't work - a 128MB work fine)
- wire directly to the teensy without passing by the phone card

I'm asking for any help - the wedding is in one week and I'm just out of solution... :/

Here is a link to the noise:
https://www.dropbox.com/scl/fi/4zfo93ejl3r3lstv99qm2/noise.mp3?rlkey=3u7ziepf4urqj0grsosggsu9l&dl=0

noise.mp3

1 file sent via WeTransfer, the simplest way to send your files around the world

we.tl

Thanks.

 

[BriComp]

This thread might have useful info for you.

 

[Natur]

Thanks for your answers.
Found out that my wiring was not so good at the end.
I missed a GND between the audio shield and teensy which fixed everything!