Help with a basic Pi-Arduino through HA project - sending a simple HIGH/LOW to turn on a LED

Hey guys so im still trying to get down some basics, so i thought to give myself a simple project.

i want to use the Raspberry PIs GPIO pins to send a HIGH/LOW signal to an Arduino pin which ive programmed to digitalread and then a different pin to digitalwrite HIGH/LOW based off the other pin’s read.
I want to control the GPIO pin’s output from the HA frontend.

This should work. I should be able to send a HIGH/LOW signal (based off the toggle in my HA front end) to a pin on the Arduino, then the Ardino should send out from a different pin the HIGH/LOW signal to the LED to turn on/off. It should be simple, right? Im just basically sending a 0 or 1 through the GPIO to the Arduino, and it should be able to act based off whether it receives a 0 or 1.

Ive already got the GPIO set up in my config file and have the toggle switch on the frontend.

I thought this would be a good project to start with to get me familiar with mmore things. Its being able to control any basic on/off switch for anything i can do with the Arduino.

Any thoughts? Even just other resources to look at

You wrote “Help” in your title yet I fail to see an actual problem that you need help with. You seem to be on the right track here. Just make sure that the voltage and current don’t fry anything on the pi/arduino. I’m not really good at those things so I can’t help you there but what you have in mind should work exactly like you described.


The gpio on the RPi are 0-3.3 V. If you’re connecting a 5 V arduino you should be fine as long as you’re controlling the arduino from the Pi, but not the other way around. If you want to connect a 5 V output to a 3.3 V input you need a voltage divider or a logic level converter in between. A 3.3 V arduino is perhaps the simplest approach, but that also depends on the other devices you want to connect to the arduino.

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So tell me which i was i was trying to do. COntroling from Pi or Arduino?

I wanted to send signal to the Arduino which it would read and then run its script to turn on the LED.

Pi output to arduino input, the Pi controls the arduino.