sms controller project

7/27/2019 Sms Controller PROJECT

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Introduction

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.



The format of the message must be only '1' or '0'. '1' to enable, or '0' to disable the device. The message m

have only 8 numbers, '1' or '0' , alone or mixed .

Example: if you send the message 11000100 then you enable, starting from the right, the devices 3,7,8 ('1'and disabling the devices 1,2,4,5,6 ('0') .

If you want to send a new message and you don't want to change some device, must send the same numbe

as the old message.Example: If you want to enable only the 5th device, you must send a new message like 11010100 to keep

other devices as there are (we send the same message as the old ( 11000100 ) and we change only the 5th b

from '0' to '1' to enable the device ).

Advice !

If you want to protect your devices from other person's messages, modify the source code, to

read the AVR, your telephone number before execute any message. In the source code I have



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]

(xxxxxxxxxxxx is the phone number of the sender)



the AVR will decode the septets message to octets, execute it (arm or disarm the relays) and send the

command

AT+CMGD=1 (delete the received message from memory position 1)

to delete the message from the phone memory.

You can see the voltage of the PortB with any voltmeter if you have +5 or 0v voltage, to check if the

command you send, for example"11001010", is executed.

sms controller project

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