Two PIR sensors sharing one digital pin?

I've used up my Arduino pins. I don't want to order in a shift register. Instead of using two separate digital pins for PIR motion sensors, can a digital data pin be shared with multiple sensors?

Would this require a diode on each data line?

Just to be sure, you used up all the analog pins?

If your PIR sensors output a high when they detect something and don't want to know which PIR was activated, just that one or both of them were, then you could add a diode from each PIR signal to the pin.

You would need a pull-down on that pin so it sees a low when neither PIR is driving high.
Something like a 10k resistor to ground.

If the PIR's output a low when they detect, then the diodes would have to be the other way around and you could make the pin INPUT_PULLUP.

Yours,
TonyWilk

aarg:
Just to be sure, you used up all the analog pins?

Yes used them all up on a MySensors network. Humidity, temperature, light, door/window reed sensors, garden moisture, lawn moisture, nrf24 radio etc… I realized I don’t care which motion sensor goes off in the garage so I may be able to combine those pins.

Some PIR sensors have an open collector output. You can just connect multiples of those to a pin with INPUT_PULLUP. Here is an example:

TonyWilk:
then you could add a diode from each PIR signal to the pin.

You would need a pull-down on that pin so it sees a low when neither PIR is driving high.
Something like a 10k resistor to ground.

If the PIR's output a low when they detect, then the diodes would have to be the other way around and you could make the pin INPUT_PULLUP.

Yours,
TonyWilk

Awesome! Thanks Tony. Testing it out now.