GsmGuard

A compact multi-purpose all-in-one open source GSM alarm system. Build on the base of Arduino Pro Mini and Arduino-compatible modules.

Features

Communication

The device sends an SMS on any alarm event and optionally a status report once a day. Why SMS and not internet service? SMS stays most reliable means of mobile communication in cases of poor signal quality, requires less energy and works directly without relying on central server (which needs to be maintained by someone and may present a security problem).

Example of an alarm SMS:

04.11.19 22:37
Movement detected

Example of a daily report SMS:

door: Closed [04.11.19 09:14] <-- date and time of last door open event
move: None [04.11.19 09:12] <-- date and time of last movement detection event
temp.: 28*C [min. 21*C, max. 28*C, mean 27*C] <-- current temperature and temperature statistics for the current day
light: 99% <-- current illumination level (0 to 100%)
bat.: 4.6v <-- current battery voltage
ext.1: 0 <-- current state of external sensor 1
ext.2: 0 <-- current state of external sensor 2

For every alarm event you can also enable a call to your phone or/and sound alarm.

Sensors

Door open sensor (magnetic reed switch)
Illumination level sensor (photoresistor)
Motion sensor (PIR sensor)
Temperature sensor (built-in DS3231)

Alarm events

Open door
Rapid illumination change
Motion detection
Too high or too low temperature
Low battery voltage

Power supply

Three AA batteries. Expected lifetime: 3 to 6 months.

Configuration and logging

The device can be connected to a PC via USB for configuration. Configuration program lets you set target phone number, time of daily SMS report, choose events that will be reported, a way of notification (SMS, call, sound alarm) and set time periods during which those events are being monitored. I.e. if you know that the room is being used during some hours in certain days of the week, you can disable the alarm for that period. It also shows the last 70 events with date and time and a temperature plot for the last 31 days (one measurement every 2 hours).

Localization

Currently supported languages (SMS and configuration program for PC): English, Russian.

Date format: dd/mm/yy

Temperature units: degrees Celsius

Assembling guide

Hardware

List of components

List of Arduino modules you will need:

Arduino Pro Mini 3.3v 8MHz (5v 16MHz is also acceptable, but requires different firmware)
MH-SR602 MINI Motion Sensor

SIM800C GSM Module

CP2102 MICRO USB to UART TTL Module

DS3231 RTC Module For Raspberry Pi

Other components

any >0.5A logic-level P-channel MOSFET in SOT-23
reed switch
buzzer 3 to 5v
electret microphone
photoresistor
resistors, capacitors

The schematics:

Important Note

Remove power LED or the resistor that goes in series with it from the Arduino board. Otherwise it will drain the batteries in a matter of few days. It is better to remove voltage regulator IC from the Arduino too, as it's not being used but still draws a little bit of current.

Giving out PCBs

I have 9 leftover PCBs of the first iteration that I can send via mail (for free). It's a first version, so it has some errors which you will need to fix with a cutter and a few jump wires. If you interested write me to

Software

Flashing Arduino

You can upload precompiled *.hex firmware to Arduino via xLoader. There's four firmware files available:

hex file	description
gsmGuard-firmware-EN-8MHz.hex	8MHz arduino, english SMS
gsmGuard-firmware-EN-16MHz.hex	16MHz arduino, english SMS
gsmGuard-firmware-RU-8MHz.hex	8MHz arduino, russian SMS
gsmGuard-firmware-RU-16MHz.hex	16MHz arduino, russian SMS

Running configuration program

Windows

Run gsmGuardConf_v1.0.exe. It requires no installation, but the unpacking process is rather slow, it may take 10-20 seconds to run.
Linux

~$ python2.7 gsmGuardConf.py

Usage notes

The device pauses its normal operation when it's connected to USB.
If the device failed to send an SMS, it will try again in 2 minutes, then again in 5, in 10, in 20, twice in 40 and then every 12 hours.
After a successful call the device will hang-up in 3 minutes.
The sound alarm will be on for 30 seconds.
Door, movement and light change events are not monitored for 20 minutes after the last reported event.
If the device's power was turned off for three hours, the temperature history gets erased.

Known issues

It looks like PIR sensors perform badly in cold temperature. Mine starts losing stability (frequent false tripping) when ambient temperature drops below +5 Celsius. I'm sure it havely depends on the particular model, though.

Project files

/config-util - PC configuration program. Python 2.7 + Tk + pyserial + matplotlib
/gsmGuard-firmware - Arduino firmware. In order to successfully compile it, you need to manually install these libs:
1. RTCLib from https://github.com/NeiroNx/RTCLib (clone the repo or use version ABOVE v1.5.8 if such release exists)
/kicad-project - KiCAD schematics and board

AlexIII/gsmGuard