Pic with gsm

[Revolver11]

can somebody give me a basic circuit diagram in building a GSM circuit to be interfaced with PIC16F877a? i really don't want to buy a pre-designed module so please help me out.

 

[georgetwo]

before you start, you need to know some points:
1) You need to know how to do serial connection using UART and how to configure it
2) You need a GSM modem (most of them support serial communication).
3) You need AT command datasheet to allow you play around till you get the best design you need

it is just a matter of interfacing, connecting 3wires from modem to pic16f877a through max232 converter,
supplying power to both mcu and modem, do your coding and so on.........

 

[Revolver11]

must be late,, but still thank you!!
can you give me more information about the AT command that you mentioned?

 

[Nigel Goodwin]

must be late,, but still thank you!!
can you give me more information about the AT command that you mentioned?

They are provided in the datasheet of the GSM module (or GSM chip) that you use.

'Generally' they are standard AT commands (as for any modem - google them), but with a few specific extras and differences.

If it's any help here are the AT strings my GSM project uses:

String0           
                dt        "ATE1", CR, LF, 0

String1
                dt        "AT+CMGF=1", CR, LF, 0

String2       
                dt        "AT+CMGS=", 0x22, 0

String8
                dt        "AT+CNMI=1,2,0,0,0", CR, LF, 0

String11
                dt        "AT+CSQ", CR, LF, 0        ; request for signal strength

String14        dt        "AT+CPOF", CR, LF, 0        ; turn modem chip OFF string
   
String15        dt        "AT+IPR=9600", CR, LF, 0    ; set to 9600 baud

String17        dt        "AT+IFC=0,0", CR, LF, 0        ; disable handshaking
       
String18        dt        "AT+CMGD=1,4", CR, LF, 0    ; delete all texts

String20        dt        "AT+IPR=115200", CR, LF, 0    ; set to 115200 baud

 

[Revolver11]

Thank you very much! It is deeply appreciated. I'll check out the link that you have posted..