Alarm system in parallel to ESP32

Hi all,

I have an old style alarm system in my house with several motion sensors which are already cabled and powered via the alarm circuit board.

My goal is to add motion sensor capability to HA using an ESP32, and was wondering if I can just run a cable from a free GPIO pin on the ESP32 to the terminal of the motion sensor on the alarm circuit board, and then simply create a sensor on ESPhome as follows:

  - platform: gpio
    name: "PIR Sensor"
    device_class: motion

Let me know and thanks all,

first post here, so please be kind :slight_smile:

A cautious yes, in that you have the right idea :slight_smile:

Some alarm systems might have a voltage on the PIR. It might even be 12v. That would kill a esp32 which is limited to 3.3v inputs.

You probably need to do some measuring with a multimeter, withsomeone wandering around activating the PIR.

Also, depending on the wiring, you may need to acrivate the esp32’s pullup or pulldown.