Interfacing GSM module with Microcontroller

[Apache79]

Hi,

 

I am trying to interface a GSM Module with the MC, AT89S52.

 

In it, I am trying to generate a call using the AT commands. I  have written the C Program which wud generate the AT command for call.

 

The problem is when I connect it, the LCD gives the display but the call isnt generated. So to debug, I connected it to the computer and cheked its output. The output came in unkown symbols and not the prefeeded AT command.

 

Please could anyone help me with the above issue, could you tell me how I can generate the Command. Should I use ASCII codes, Binary codes or anyother code?

 

Any help in the above would be hghly appreciated, I have reffered to all of the listed projects dealing with this topic in EG.

 

Thank You

[phanindra nath]

 

what you exactly want to do is- call some mobile no. from the SIM card which you placed in the GSM module.If this is wat you want then,

 

first check weather messages are transfering or not?

if yes, then calling also should work.

[Apache79]

Thanks for the reply, I tried calling after connecting it to the computer’s hyperterminal it works fine. But when I connect it to the Circuit, the LCD gives the message but the call isnt generated.

 

To check if the command is being generated from the MC, i had connected it to the hyperterminal, the codes I recieved in it were symbols and not the AT commands which was feeded in the C program.

 

Please could you help me with this difficulty, 

 

Thanks

[Apache79]

I am connecting the GSM Module to the MC with pins 2(tx), 3(rx) and 5(gnd). Should i connect the other pins of the RS232, or short them in any way?

 

I read somewhere that we have to give +9v to pin 7 and -9v to pin 4 of DB9. Is it true?

 

Please guide, 

 

Thanks

[phanindra nath]

only Tx,Rx and GND connections are enough.

i think only Ascii characters should be sent to hyperterminal.

for example:

 send_serial(49); means ASCII value of 49 ie.,’1′ is sent to the terminal

send_serial(49); is same as send_serial(‘1’);

is it the same way you sent to serial port?

 

if you have some time check my blog

[Sathish]

Hi sir am also having a doubt, I want to use the mobile as a gsm modem, am having nokia X2-00, by using this mobile i can able to send the messages to other mobile by using the AT commands but not able to receive. Can you please tell me the solution.

 

[phanindra nath]

@satish 

how did you use mobile as GSM modem? and how did you sent the messages using the AT commands to the other mobile? 

[SUNNY PACHORE]

 how can i call througth gsm module.???

 

[Abhinav Sharma]

when you are generating the code jst try to send character “A” first and then the rest of the commands.

it will sinc the baudrate.

and chek the crystal used.

 

If you are using 8051 microcontroller the value written in crystal should be exactly 11.(somthing)

but it should not be 12 MHz.

[Nikita]

hello all…

    I am also trying to interface GSM modem(sim 900) along with micro controller using PC and LCD. I have followed the instructions provided in this website! The link to the that is given below:- http://www.engineersgarage.com/microcontroller/8051projects/interface-gsm-module-8051-microcontroller-circuit-code.

 

But the thig is when i execute it, there is no echoing from thePC when I type AT Commands in the hyper terminal, also my LCD is completely blank and does not show any message. I am using NXP micro controller (P 89V51RD2BN). 

ANy help in this regard would be highly appreciated.

Thank you..
              

[jay]

hi all.

i had same problem of not calling.

please download atcommand set pdf file from net and do as guided in it. if still not working please check your pwr supply. it must be atleast 2 amp for calling.

[AJISH ALFRED]

Hi Apache,

Please check your baud rate settings. 

Also try with the baud rates 9600 and 4800 with the hyperterminal.

[Author]

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