Motion Alarm

The following is a description of a motion alarm. This would be a first step towards replacing my current, retail alarm system. Let me know what you think.

The system consists of remote PIR motion sensors and a monitoring station that sends text message alerts.

The motion sensor would use a low power processor, sleep library (JeeLib) and barebones Arduino (no voltage regulator) to increase life. It would connect to the monitoring station by an RF Link.

The monitoring station would send alerts by text message on your home network using twilio. Texting would only work when wireless network is up.

Monitoring station
Raspberry PI
RF Link Transmitter – 434MHz
AC Adapter

Wireless PIR Sensor
Atmega328P based Arduino
RF Link Receiver – 434MHz
2xAA batteries

Before you do any planning, what does your insurance company have to say about you changing you security system?

Tom... :slight_smile:

Yes, central monitoring is required for the insurance discount. State Farm Mutual, for example, offers up to 15 percent for a preferred system with central monitoring that includes notification of emergency personnel but only up to 7 percent for a system with central monitoring that notifies only the homeowner.

It will have to be part of the final plan. l currently pay $45 a month for monitoring. There are lower cost providers.

I doubt they will respect DIY solution as it is not certified/tested etc....

Well you are probably right. Could switch current system to low cost monitoring for insurance discount and not use.

It's a shop alarm or in your own house?

If it's in a shop better keep the security company system.
If it's in your own house then who gives a fk about insurance company "Tom"


it is an alarm for my house. I can keep the existing alarm for insurance purposes.the system as described was not intended to be a final system. it does not even include a is a minimal system that would be useful. let's call it day one.

does anyone have any non-legal feedback?

Your PIR will have to have at least a TX not a RX and your Monitor the Rx.

If you are aiming to have more than one PIR, I assume you will not be polling them due to power constraints.
The 328 will do the job, works 1.8V to 5V, it should be okay in minimal form, you may have to investigate power consumption of entire module.
If you drop the clock frequency to get more battery life, you will have to recalculate you comms baud rates too.

Tom...... :slight_smile: