Troubles connecting a sensor to multiple arduinos !

Hi there !

On my current project, I would like two different arduinos to read the state of some hall sensors. My plan was to simultaneously connect a hall sensor to a pin of each arduino. However it seems that it ruins the results. Now, when one sensor is HIGH, all the other sensors turn HIGH as well. It seems that the second arduino actually connects all the sensors between them (even if it is unpowered and basically completely unplugged besides the hall pins). Aren't the pins isolated from one another ? How can I wire a sensor to two arduinos ?

Thank you in advance for your help.

A hall sensor with analog output ?

Connect the GND of both Arduino board. And GND to the hall sensor. Use the 5V of just one Arduino board for the hall sensor. The output of the hall sensor to inputs on both boards.

Thank you for your answer. The 4 hall effects sensors that I am using are on plugged to digital pins.

I did as you said, however it is still not working. Actually, even if the second arduino is wired to the GRND, as soon as I wire the sensor to it, the sensor turns HIGH (when it is supposed to be LOW)...

can you post an image of how it is connected? a photo of a drawing is sufficient..

Why not a more general approach? put one Arduino in control of the sensor and send its result to the other Arduino's (opt. on request) Then you need to solve one generic problem (let multiple Arduino's communicate)

Thank you !

A photo of the wiring :

Right now, the hall sensor 1 is wired to both arduino and its status is on HIGH, it should be LOW. It turns LOW if i unwire it from the unplugged Arduino MEGA.

I will also explore your solution of wiring it to 1 arduino and making the two comunnicate.

If one of the Arduino boards is not powered, the inputs are pulled to ground because of the internal protection/clamping diodes. Is that the problem ?

YES ! When the second arduino is powered it seems to work fine. THANKS ! I learnt something today.