4 doors sensors and 4 move sensors on the same node

[carleki]

Hello,
In my house, I have an old alarm system installed, with :

• 4 doors sensors
• 4 move sensors

All the sensors are wired, and all the cables are going un a closet, where the old alarm system is installed.

I don't want to use the old alarm because it is broken, but I want to reuse the sensors. I have electric power in the closet, so it will not be a batteries powered node, so is my idea realisable :

• Arduino powered by USB, with at least 8 inputs (arduino uno ?)
• I connect 1 cable of each sensor on each input
• the other cables from the sensors connected to ground of the arduino

is it correct ?

[gloob]

What type of sensors are they? Do they act like simple "switches" or what kind of signal do they offer on the output?
An Arduino nano also has enough inputs to connect 8 sensors with on/off signal.

[carleki]

@gloob said:

What type of sensors are they? Do they act like simple "switches" or what kind of signal do they offer on the output?

For the door, I assume they are like reed switch (with magnet fixed on the door itself)
For the movement ... I don't know !

[gloob]

If the door switches act like normal reed switchen then it is correct that you can put one wire to ground and the other one on an input of the arduino.
Internally you can set the pullup resistor on the pin and check when the signal goes to low, to detect that the door is closed. If the door opens and the reed switch is open, you will get a high signal from the input pin.
But you can also connect one pin of the sensor to 5V and the check if the output pin of the sensor goes to high when the door is closed.

For the movement sensors you have to check the signals. There should be at least 3 pins for each sensor, power, ground and the signal itself.

[carleki]

@gloob

ok ! I will check the wires and signal output from the movement sensors