1. Preface

1.1 Project Overview

DefendLine is an open hardware/software project allowing to guard remote objects via GSM channel. Why design one more GSM based security system, nowdays there are tons of them on the market available? The answer is simple: the systems produced in lots are rather expensive and at the same time do not quite fit everyone's needs. This solution is based on maximally simplified microcontroller which comprises of low-cost and easy-to-find components. Simple system does not necessary have to be primitive. This one was thought to be flexible and extendable and to use as much functionality of external GSM device as possible. In minimal configuration it is capable of handling 4 external detectors, controlling 2 external devices by switching them on/off, performing programmed actions on timer events, being controlled by means of SMS commands, detecting power outages and automatically switching to backup power source. If external GSM module is presented as a mobile phone with embedded camera and Java support, digital pictures can be taken and sent via HTTP. Extension connector might be used for LED display interfacing or for increasing numbers of input/output lines. There is an option to interface iButton (1Wire) devices by means of separate 2-pin connector which allows to use temperature sensors, touch memory, secure and authentification tags etc (see http://www.maxim-ic.com/products/1-wire). Open source firmware gives obvious advantages, it boosts system's flexibility, stimulates further improvements and development, allows custimisation and tuning to meet client needs. All abovementioned features make the product quite competitive, uncover its huge potential to not only experienced engineers but juniour developers and hobbists as well and open new horizons on a field of creative work.

Thank you and good luck,
DefendLine Development team