[quote author=Coding Badly date=1493061435 link=msg=3234185]
All the PIRs I have are open collector so, yes, it is possible to have a shared signal.[/quote]
The PIR’s I have are certainly not… So that would create a dead short… You could use diodes and a pull resistor though. Depending on active low or active high a pull up or pull down resistor.
I do not know if I have open collectors in my PIR’s, but when I connect as the schematics in the first post (I forgot the ground to the Arduino board in the picture), then it seems to short, not dead short, but half of the voltage. The output becomes 1,5V instead of 3,3V, and so I guess this is also what Wawa talks about.
I am not sure how you mean with “diodes and a pull resistor”, but I connected as the schematics I attached in this post, with two 1N4148 and one 1Mohm resistor. And it seems to work now with two PIR’s.
Do you think I could do the same with all the other PIR’s, eight in total, just add one diode for each PIR?
Is it possible to connect an endless array of PIR’s with this layout as long as the power source manage it?