Hello all,

for my Controller-Project Im using a Teensy 3.5 at USB Power (Laptop)

the upper console-part constist of 8 buttons, which work fine.
the lower console-part there are
1xmcp23017 @3.3V, I2C
1xmcp3008 @3.3V, SPI
3xHall @3.3V
1xSN74HC595N for 3x3mmgreen LEDs as indicator for switches. Its connected to 5V
2xSN74HC595N for a 7SegmentDual Display, also connected to 5V
1x linear potentiometer 10k@5V.

connected to the teensy

So I "parasite" the 5V USB current where the teensy is connected to deliver the 5V.

Problem:
Axis flicker and jitter dramatically especially with the 10k pot connected. If I put the pot-lever up, the axis totally "answer" it.
When disconnecting all the bottom 5V devices and driving the 3 Halls @3.3V instead of 5V everything works fine
I also tried bidirectional converters, the jittering got better, but didnt really dissapear, the potentiometer influence still was notiiceable. It only works like a charm at pure 3.3V, but then I can forget the complete lower console-part

I tested a lot, feels like this basic scheme is a problem itself. So my question is: How to connect and drive 5V devices correctly beside the teensy from 1 usb port? Cap or other components maybe? Or do I need an external powersupply?


Thanks for help!