Wireless House security system

Hi guys,

I am totally new to Arduino and would appreciate any advice I can get.

I want to build a security system for home. Each PIR (four in total) needs to be connected to a wireless transmitter, which would send a signal to the main arduino board if the pir is triggered.

I need to know what arduino devices to purchase - For each transmitter i would like to use a simple (cheaper) arduino. And aslo I’d like to know what the model of the main control board should be. (Bearing in mind I’m trying to keep the cost as low as possible)

Any help would be highly appreciated.


buy wireless sensors, don't try to build your own. you only need to have a receiver and any arduino, the mini or NANO or uno or pro-mini will work.

Hi Dave,

Thanks for your reply.

I already have sensors which are positoned in my yard. These relay points that close or open when triggered. I need to transmit this alarm condition to the Arduino.


I have a system using NRF24L01 radios and Arduino Nanos. If you're willing to wait, all you require (5 radios and 5 Arduinos) can be had for perhaps less than $30. PIRs on ebay are also inexpensive. Don't forget power supplies; other minor components will be needed before you're done.

The receiver in my system is in the basement and the farthest transmitter is on the second floor. Conditions in any environment will determine whether these radios, or any, will reliably work.

Bear in mind that most versions of NRF24L01s are not breadboard friendly, meaning you will need adapters. My 'adapters' are ribbon cables I made that are NRF24L01 friendly on one end and standard breadboard spacing on the other end.

Another consideration is that breadboards are not intended for a permanent installation.

Once a 'detection' is received by the receiver, what are you intending the receiver to do?

For NRF24L01 radios, there is much information, such as forums, data sheets, Instructables, and Youtube videos available. Even so, being totally "new to Arduino", this project (as a whole) may be overwhelming and might become no fun at all. However, breaking this into separate projects, i.e. Aruino/PIR and Arduino/NRF24L01, would certainly avoid some possible frustration and might give you enough understanding of each project to enable you to get them together as one project later.

  • Scotty

Hi Scotty,

Thanks for your reply.

It is my intention to break this Project up into little projects, just as you have advised :)

Once an alarm state is received by the receiver it needs to inform me, maybe by sounding a buzzer for several seconds. ( This can be modified later to include a LCD screen that tells me exactly which sensor has triggered)

My first goal I think should be to connect up the sensor to a transmitter and get it to transmit a signal to the receiver?

I highly appreciate your help

Well no, the radio doesn’t have any processing capabilities nor does it have any GPIOs.

What I think might be a good start would be to connect a PIR to an Arduino and code the Arduino to do stufff based on the signal from the PIR, e.g. turn on an LED, flash an LED for a length of time even if the signal returns to it’s ‘no-detect’ state, send output to the serial monitor, etc… Then connect additional PIRs to the Arduino and code the Arduino to do stuff based on which PIR(s) have or don’t have ‘detection’. Having done that should give you a good foundation for that function. Take care to document code and wiring.

Then move on to the radios (in this paragraph, a transmitter or receiver consist of an Arduino, NRF24L01 pair). Just have a transmitter send data to the receiver. Do the same as with the PIRs. If certain data was transmitted, do this; if other certain data was transmitted, do that. Then move on to control when the data is sent, e.g. send the data when a switch is depressed. Once comfortable with that, introduce another transmitter into the network. Have the receiver do this if certain data was received from transmitter A, and do this if certain data was received from transmitter B. While you’re at it, get a feel for the range you may be able to reliably attain within the environment of this project.

As you might already imagine, it shouldn’t be a big jump to replace the switch input that triggers data to be sent with the signal from a PIR.

  • Scotty

Hi Scotty,

Thanks once again.

I intend to have an arduino at each PIR, as they are not located together. Which model Arduino would be suitable for this? Maybe I can purchase them and connect up to the pir like you suggested.


VincentM: I intend to have an arduino at each PIR, as they are not located together.

You don't need so many Arduinos. You only need one Arduino equipped with a receiver and wireless PIR's. Don't buy the super cheap $1 receiver (I only get 3m range), buy at least the $2 receiver (I get 25m range) - gee price has dropped since I bought mine. The $5 one will give u more than 40m.

My bad - I should have mentioned that these are special outdoor PIR’s which I have already.

VincentM: My bad - I should have mentioned that these are special outdoor PIR's which I have already.

If I were u, I would still consider buying wireless sensors.

IMHO it will be better than having to add an Arduino + transmitter to each existing PIR and u won't need any code either. Remember you would also need to weatherproof each Arduino.