Thanks for reading. I'm using the Teensy 4.0 with the audio adapter board rev d.

This is a simple synth using 2 adafruit MPR121 capacitive touch sensor boards that trigger synth notes.
Scale, key, octave, wave form are selected via rotary switch and LCD menu.

1. Should all of the ground pins be connected as in my schematic?
2. Should all peripheral devices (MPR121, LCD be powered via the Teensy's 3V supply as show in schematic?

U4 is a header for connecting 2 MPR121 capacitive touch sensor boards via I2C

U5 is for an LCD (20X4) LCD has a toggle switch (SW2) for cutting off the 3V supply to it.
(LCD is from Amazon by company called Hosyond, where it's stated that it requires a 5V supply, but I've been using it with a 3V supply from the Teesny's 3V supply pin with no problems, could it become a problem?

SW3 is a rotary encoder with push button switch.

*I use Q3 (a p-channel MOSFET) for reverse polarity protection.

Audio out is mono from LOUT.

Sincere thanks for any advice/help. Appreciated!
TonyAm

 

The analog and power grounds should have separate paths to a single "star"ground.

 

The analog and power grounds should have separate paths to a single "star"ground.

Thank you. I'm not really sure what you mean, do you know of any examples on the web I can check out?
Thanks,
TonyAm

 

Google "star grounding systems"

 

Google "star grounding systems"

Ok, will do thanks.