Top-Rated Free Essay

Sms Based Control System

Topics: Mobile phone, GSM, Text messaging, Nokia, Serial port / Pages: 4 (801 words) / Published: Jul 13th, 2010
Have You Ever Thought Of How To Turn Your Mobile GSM Phone To Be An "SMS Controller"?
You should have read THIS and understand it first just before you proceed to read "SMS Controller" articles SMS Controller Headache looking for a solution on how to interface your GSM Phone with AVR Micro-Controller? If you patience enough you might find the solution right-away from here. Build your very own SMS controller with a truly detailed instruction from scratch! A step-by-step guidance will be tought here. All you have to is to have:

• • • • • • • •

Some basic electronics/electrical knowledge Ready with some basic electronics tools such as soldering iron, multimeter, etc. Relevant electronics components (we'll describe later) AT capable command mobile phone (we are using several models ericsson T10 and T39) Master mobile phone (for sending and receive command) A PC AVR Programmer of any kind AVR compiler

DLR3 cable for for serial cable connection to T39 (original kits from ericsson though it comes from ROC!).

Step # 1
1. 2. Let's download the SMS Controller circuit diagram


and print it

Get ready of all the components as listed in the circuit diagram

3. Install the components to the PCB (writer is using a cut of bread-board!) and inspect thoroughly so as not to have short or open circuit 4. For a reference, please find the the prototype of SMS Controller or Interfacing hand phone with AVR micro-controller.

5. The writer purposely show the prototype without any enclosure as well as with some fly-wire to indicate the real ones built from scratch!You can alter or arrange all the components base on your suitability as you like. 6. The serial connection to the PC is an optional but really helpfull particularly when you get stucks. Remember! Do not expect that your prototype is working as expected very easily! So, it is here where you must have the serial link to PC for trouble-shooting is necessary. By doing this you will eliminate from being developed two different PCB board 7. Use a hyper terminal PC with a setup of 9600, 8, N, 1, N to test any command

Step #2 - Learn AT Command
1. In order to understand how the sms works, ones should at least understand of the AT command works, as SMS on ericsson (now Sony Ericsson) work trough AT command when sending and receive SMS To test whether you phone or relevant accessories is working with AT command or your sets isworking, make a connection from T39 phone to PC via serial connection. Execute the AT command setup as indicated below


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Open the Hyper Terminal Windows and set the parameters as follows

Start AT Command Instruction

from your PC keyboard, type

AT and enter.
(Note : cell phone responses are blue)

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Now, it indicates that your handphone is communicating with
4.2 First, tell the phone which memory to use for successive commands: Type

PC via serial port communication.

AT+CPMS="ME","ME"+CPMS: 7,15,7,15,7,15

This instructs the mobile to use internal memory "ME" in place of the a message can be read from at memory specifying its number "SM" memory from the SIM as default memory Next,

Next type AT+CMGR=4 +CMGR:1,,27 0791934329005000040C919343372850140000106031 4104350809D02A735A043DAB54 OK
This is the fourth message, 1= received and read 27 bytes long text, in PDU (Protocol Description Unit) format. The PDU format is quite complex, as it contains many subfields packed together using different encodings. Among center numbers, origin numbers, nation codes, a time stamp and a descriptor of charactor set used. For more detaild information, refer to the "SMS DATA DISSECTED": for our purposes it is sufficient to know that the text bytes are on the rightmost position Storing the "isgnature" from the last 6 bytes of the message, the device will be able to recognize incoming messages. Right now, we are able to download messages from the phone. The next command frees precious mobile memory deleting the seventh message:

The last step is to send an SMS message. This proved to be more difficult step. But all we need to do now just follow the below mention AT instruction

OK Through out these procedures, we only need to carry out 4 basic AT commands in our interface programming in order to finalize it. Thereafter, all the AT commands will be included in the source codes.

For the details please login to

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