1IntroductionWith this circuit we can control up to 8 devices (4 devices in our example project), by sending a specific SMS message with any mobile phone. It's very useful in the case that, at the place we have the devices, we have not a wired (fixed) 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 orReset. Usage of this circuitWith this circuit y ou can switch-ON , OFF or Restart some Linux servers, ADSL modems, Printers, Doorwith electric lock, Garage door, House lights, Waterpumps, 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 mak e the human life better and easier. The circuitThe hardware of the circuit is very simple, because the communication port of ericsson mobile works at the 5 volts with AT commands ( like the mod em commands, but for mobile phones).
This document is posted to help you gain knowledge. Please leave a comment to let me know what you think about it! Share it to your friends and learn new things together.
With this circuit we can control up to 8 devices (4 devices in our example project), by sending a specific
SMS message with any mobile phone. It's very useful in the case that, at the place we have the devices, we
have not a wired (fixed) telephone line. If you have an old ericsson mobile phone and you are not using it,the time to build some useful with that. The controlling that we can do to the devices, it is ON , OFF or
Reset.
Usage of this circuit
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 mo
The purpose of this circuit is to make the human life better and easier.
The circuit
The hardware of the circuit is very simple, because the communication port of ericsson mobile works at thvolts with AT commands ( like the modem commands, but for mobile phones).
The firmware of the AT90S2313 (or ATtiny2313) is very complicated because, we have to convert the
'septets' of the phone into 'octets' because the AVR needs bytes with 8 bits length ( The 'septet' is 1 byte w
7 bits length and 'octet' is 1 byte with 8 bits length). All this process is necessary for decoding the text
message from the SMS.
This circuit is working on both AT90S2313 and ATtiny2313 microcontrollers. In case of ATtiny2313 yohave to select "External Crystal Oscillator" instead of default "internal RC oscillator" from
the "Fuses" tab of your programmer's software. You have to uncheck the "Divide clock by 8 internally"
>> Schematic of SMS remote control circuit.
When you finish the circuit connect it to the mobile phone, turn on the phone and then power on the
circuit, not before . The AVR will try to read the message from the 1st memory location of the phone, forthat I suggest you to delete all SMS messages from the phone before you connect it to the circuit. If there
no message to the 1st memory location, the AVR is trying again until you sent any.
some part of code, to read the telephone number, the service center number, the date and the ti
of the received message.
The project its based on the Greek mobile phone network of <Vodafon GR> and i don't know
the SMS message in other country, have the same syntax ( I mean the form of the septets that t
GSM receiving from the GSM network ).
After the GSM receive the message, the AVR execute it, delete it from the phone memory, to
release the 1st memory location and starts again the searching for a new incoming SMS
message.
Service mode
If you connect the pin7 (PD3) of the AVR to MAX 232 chip and this to computer, you will see atthe terminal window software, all the data that the GSM sends to the AVR (Sender's number, service cente
number, date, time and the AT commands ) . Setup the COM port to 19200 bps 8n1.
Troubleshoot
I have test it only with Greek sim cards and T10s mobile phone. I don't know if this circuit works fine to
other cell phone providers in other countries or other mobile phone models. You can build the optionaldiagnostic circuit that is in the dot frame of the schematic, and to connect the circuit with PC via RS232 po
When you power-on the circuit and the phone, the AVR will send the following commands to the mobile
phone:
1) AT+CPMS="ME" (Select the phone memory "ME")
and2) AT+CMGR=1 (read the received message from memory position 1)
If the mobile phone will response with:
AT+CMGR=1[CR][CR][LF] (this message is sent when there is no message in the phone memory)+CMS ERROR: 500[CR][LF]
On this case the AVR will send again the commands 1 & 2
If the mobile phone will response with:
AT+CMGR=1[CR][CR][LF] (this message is sent when a new message arrives in the phone memory)
+CMGR: 0,,26[CR][LF]
0791039624910000240C91xxxxxxxxxxxx00003001205151302108B1180C068BC162[CR][LF] OK [CR][LF]