I am new to Arduino, and I have a problem that I can't solve on my own. I am trying to connect multiple PIR motion sensors with a single wire, in parallel and onto one pin on my Arduino.

I am thinking of putting a different resistor on every sensor so when motion is detected and electricity goes through the sensor, the Arduino can detect how much voltage has come to Arduino. I don't know, this is the only solution I could come up with.

  • \$\begingroup\$ it would be better if you can post the type of PIR \$\endgroup\$
    – Damien
    Commented Dec 28, 2021 at 10:09
  • \$\begingroup\$ Do you need to identify which one is set of, and if so, even when more than one is set off at the same time? Or only know that at least one of them has been set off? \$\endgroup\$
    – Klas-Kenny
    Commented Dec 28, 2021 at 10:13
  • \$\begingroup\$ PIR sensors usually have a N/C switch. If you connect them in series, with a different resistor across each switch, you can construct a ladder network whose resistance will show which sensor has become open circuit. \$\endgroup\$
    – user131342
    Commented Dec 28, 2021 at 10:21
  • 1
    \$\begingroup\$ @Vid I'm seeing the datasheet say "TTL output: 3.3, 0" (which isn't TTL.) I also see a series resistor going to the output pin. Is this what you also see? Or did I get the wrong datasheet? \$\endgroup\$
    – jonk
    Commented Dec 28, 2021 at 17:37
  • 1
    \$\begingroup\$ Why don't you start with your definition of "multiple"? 2? 10? 1000? \$\endgroup\$
    – Maple
    Commented Dec 28, 2021 at 19:48

1 Answer 1


Make a DAC converter with the outputs (through the 1k internal resistor).

The bit of the binary value of voltage is directly related to the PIR which has detected something.

EDIT: R1 should be 2*RR.

enter image description here


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