With this circuit we can controll up to 8 devices (4 devices in our example project), by sending a specific SMS message with any mobile phone. Its very usefull at the cases that, at the place we have the devices, we have not a wired telephone line. If you have an old ericsson mobile phone and you are not using it, its the time to build some useful with that. The controlling that we can do to the devices, it is ON , OFF or Reset.
With this circuit you can switch-ON , OFF or Restart some Linux servers, ADSL modems, Printers, Door with electric lock, Garage door, House lights, Water pumps, electric sunshade, Block the engine of your car or your motorcycle, at the steal case and much more. The purpose of this circuit is to make the human life better and easier.
The hardware of the circuit its very very simple, because the communication port of ericsson mobile its working at the 5 volts with AT commands ( like the modem commands, but for mobile phones).
The firmware of the AT90S2313 (or ATtiny2313) its very complicated because, we have to convert the 'septets' of the phone to 'octets' because the AVR need bytes with 8 bits length ( The 'septet' is 1 byte with 7 bits length and 'octet' is 1 byte with 8 bits length). All this proccess its necessary to decode the message from SMS.
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