I have an project which control a heat exchanger.
I read 4 temperature sensors DS18B20, a distance with HC-SR04 Ultrasonic Sensor, and a flow with YF-S201 (with attach interrupt). I can turn on and off a monophasic motor with Arduino too.
I have many interference problems with i turn on my motor, the readings of temperature fail with big frequence and i have many errors with interrupt counter.
I read many posts about interferences, and one most important factors are high impedance of floatings pins.
I use Arduino Due, then many pins are floating. I have to put a pull-down resistors in all pins?
My project looks like the architeture in the image link bellow: https://i.sstatic.net/glo5L.jpg
The code of my project can be found in : https://github.com/felipefonsecabh/ArduinoCode/blob/ArduinoNoNavigation/ArduinoCode.ino
Any opinion?
