Interface Pic --> Max232 --> GSM Modem

[LogX]

Hi..
I'm new to PIC.
I'm trying to interface PIC and GSM Modem using Max 232.
How to initialize the modem and Max232 (using assembly)?

PIC16F873A
Modem: MOD 9001 GSM/GPRS

Plz reply ASAP.
Thank You.

 

[Wilksey]

Do you know how to program in assembly?

You should read this:


Look at Tutorial 7, it is related to RS232.

You dont need to "initialise" the max232, it acts a "transparent" chip.

Wilksey

 

[LogX]

Ok.
How to send sms using pic by sending command to gsm?

 

[Wilksey]

You need to learn the AT commands, download the AT command set for your module, then you can send them out on the UART using the code on Nigel's tutorial pages.

Wilksey

 

[LogX]

Thanks alot Wilksey for your guidances..
I need one more help.
How to use sms that we sent to modem (modem goes to pic) to control our system?
For example, send 1 to ON the system, 2 to off the system, 3 to ON the light etc..
Let say we send 1, how shd i programe the code in PIC to receive the sms and react accordingly?

 

[fermat7]

Hi LogX...

try first to read SMS correctly by your chip... it's so simple just use the AT commands of ur mobile
when that's done , think to treat data according to commands you defined

 

[Wilksey]

As fermat7 has said, you need to look up the AT command set for your modem, ideally you would want text mode not PDU.

PDU Causes unecessary headaches!
Wilksey

 

[LogX]

Ok..
Im still having problem at the receiving part.
When i connected PIC to pc n tested with PIC Simulator it works, but
with modem it doesnt works.
Is it because of the baud rate value and Fosc?
The modem's baud rate is 115200bps, but i set 9600bps in PIC using 4MHz xstal.
But im still can send the SMS, but the prob is recv data from modem.

 

[DirtyLude]

Are you sure your modem is using RS-232 and it's not just straight logic level? Apparently there is a jumper in the module to change it between the two.

 

[Wilksey]

The modem's baud rate is 115200bps, but i set 9600bps in PIC using 4MHz xstal.

If your baud rate, parity etc do not match you will get no comms between the PIC and the Modem.
Most modems use the same command of AT+IPR=XXXX where XXXX is your speed, use 9600 as a standard. Most of the modems I've used also have an automatic baud rate system where you can connect to it at whatever speed.

Also, as DirtyLude has mentioned, some modules work using TTL as well as RS232, I use frequently a sony ericsson / wavecom GR64 which can have both interfaces.

 

[THIYAGU]

Help

HI....I'm study in politeknik....i need ur help cz nw me do cane recycle gsm sms systems.....project in my study so i d'n know to interfacing gsm modem into pic 16f877a plz give me full detail about this sysytems

 

[LogX]

Thanks to all of u guyz who helped me in this thread..
I have succesfully completed my project.

So THIYAGU, which poli r u from?
Do u mean CAN recycle gsm sms systems or cane?
Anyway, to use GSM modem u need to study about AT COMMANDs.
To interface modem and PIC, u have to use MAX232 chip.
U can get the interfacing circuit form the datasheet.

 

[THIYAGU]

Hai gus...............
I'm new to pic n gsm.........i want to know how to interface gsm into pic........and want to know about gsm.....me use pic 16f877

 

[THIYAGU]

Me 4m poli kulim kedah..........cn u gv the details all about how to interface gsm into pic plz........

 

[LogX]

As i said, u need to use MAX232 chip and RS232 port and cable.
U try to search for MAX232 configuration. Thats all..

 

[nitin.kaul]

hi i wnt to interface 8051 with gsm.
can anyone tell me how to do that.
if someone can provide me the programing for sending and recieving of sms between gms and 8051, it will b geat.

 

[Wheateus]

Hey, I'm doing a school project very similar to this using a Picaxe IC to read variable inputs, define the situation and then send this as a text message. I have read that I might need a Max 232 to send the serial signal to a mc 35 Siemens GSM modem, can anyone help with both the schematics and the programming?

 

[Nigel Goodwin]

Hey, I'm doing a school project very similar to this using a Picaxe IC to read variable inputs, define the situation and then send this as a text message. I have read that I might need a Max 232 to send the serial signal to a mc 35 Siemens GSM modem, can anyone help with both the schematics and the programming?

If it's an RS232 modem, then you need a MAX232 (or similar) to connect to it.

I can't help you with PICAXE programming, but the required MAX232 circuit is covered in my PIC tutorials.