ScopeMaster
Member
Hello everyone, I have been going crazy for days around a noise problem on a project that I am carrying out.
I am in an advanced test phase of a Eurorack module with Teensy 4.1 associated with the SGTL5000 codec (the diagram is directly taken from the Audio Board PRJC)
The teensy also controls the controller of the board's LEDs on the I2C Bus.
I used the audio tools utility to create the audio chain.
By plugging the module into the rack
My code generates a fixed 320 Hz noise which is clearly audible at the output.
I immediately thought of a ground loop due to a design error.
I then mounted a teensy with the original audio board in piggy back on the teensy on a breadboard and inserted into the rack.
Noise is always present.
Furthermore, when the I2C BUS writes to the LED controller, a noise of 100 Hz is added to the audio output.
I thought of an excessive absorption of the LEDs such as to create an excessive ripple on the eurorack power supply, but the same happens on the test breadboard where neither the controller nor the LEDs exist.
if I upload the SIMPLEDRUM sketch:
https://github.com/PaulStoffregen/Audio/tree/master/examples/Synthesis/SimpleDrum
the 320 Hz noise disappears and the sound is perfect.
on this sketch there is no control of the LEDs and writing on the BUS.
I am almost certain that the problem is caused by the higher CPU absorption of my sketch compared to the SIMPLEDRUM and that a board design problem creates a BOUNCE GROUND that introduces noise, but then why with the original Audio Board mounted directly on another teensy is the noise always there? The layout of the audio board and teensy are perfect for all applications, I shouldn't have noise on that.
thank you all for the possible advice.
I am in an advanced test phase of a Eurorack module with Teensy 4.1 associated with the SGTL5000 codec (the diagram is directly taken from the Audio Board PRJC)
The teensy also controls the controller of the board's LEDs on the I2C Bus.
I used the audio tools utility to create the audio chain.
By plugging the module into the rack
My code generates a fixed 320 Hz noise which is clearly audible at the output.
I immediately thought of a ground loop due to a design error.
I then mounted a teensy with the original audio board in piggy back on the teensy on a breadboard and inserted into the rack.
Noise is always present.
Furthermore, when the I2C BUS writes to the LED controller, a noise of 100 Hz is added to the audio output.
I thought of an excessive absorption of the LEDs such as to create an excessive ripple on the eurorack power supply, but the same happens on the test breadboard where neither the controller nor the LEDs exist.
if I upload the SIMPLEDRUM sketch:
https://github.com/PaulStoffregen/Audio/tree/master/examples/Synthesis/SimpleDrum
the 320 Hz noise disappears and the sound is perfect.
on this sketch there is no control of the LEDs and writing on the BUS.
I am almost certain that the problem is caused by the higher CPU absorption of my sketch compared to the SIMPLEDRUM and that a board design problem creates a BOUNCE GROUND that introduces noise, but then why with the original Audio Board mounted directly on another teensy is the noise always there? The layout of the audio board and teensy are perfect for all applications, I shouldn't have noise on that.
thank you all for the possible advice.