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[SOLVED] problem in communication with gsm modem and pic

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thunderboympm

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hello,
i got stuck with my GSM modem, i am doing a project with PIC16F877A and GSM modem (sim300 V7.03)
the problem is, when i am giving "AT\r" to microcontroller GSM modem not responding.
i checked
1. Connected to serial port using com port in my pc, the result is good gsm modem responded with "OK"
2. Connected my board to Serial port using com i got "AT" in my serial terminal "teraterm" and i gave "OK" then the code working perfectly
3. When i combined the two with a connector wire of three pin then the system is not working properly

will you please suggest any remedies or solutions with your experience? and if you can please describe what is the problem actually?

thanks in advance
 

\b (backspace) Moves the active position to the previous position on the current line. If the active position is at the initial position of a line, the behavior of the display device is unspecified.

\n (new line) Moves the active position to the initial position of the next line.

\r (carriage return) Moves the active position to the initial position of the current line.


I think you need or try \n and ur problem will solve
 

hello,
i got stuck with my GSM modem, i am doing a project with PIC16F877A and GSM modem (sim300 V7.03)
the problem is, when i am giving "AT\r" to microcontroller GSM modem not responding.
When i combined the two with a connector wire of three pin then the system is not working properly

Is the interface between your GSM & PIC is through UART communication?
 

Is the interface between your GSM & PIC is through UART communication?

Yea
It is in asynchronous 8 bit mode with a board rate of 9600

- - - Updated - - -

\b (backspace) Moves the active position to the previous position on the current line. If the active position is at the initial position of a line, the behavior of the display device is unspecified.

\n (new line) Moves the active position to the initial position of the next line.

\r (carriage return) Moves the active position to the initial position of the current line.


I think you need or try \n and ur problem will solve


But in the datasheet of sim300 says that it needs only the "CR" character only.
But i'll go through the suggestion. After that I'll update you tommorow evening

Anyway thanks buddy
 

Yea
It is in asynchronous 8 bit mode with a board rate of 9600...
You didn't undestand the question. Is the voltage LEVEL in UART or RS232 specification?
UART uses 5V/0V or 3.2V/0V (or even 1.8V/0V) while rs232 uses -9V/9V (approximately).

PIC requires UART. Your GSM requires UART or rs232?
You should also be aware that UART level may be 3.2V or 5V aware. Checks specs of GSM module.
 

You didn't undestand the question. Is the voltage LEVEL in UART or RS232 specification?
UART uses 5V/0V or 3.2V/0V (or even 1.8V/0V) while rs232 uses -9V/9V (approximately).

PIC requires UART. Your GSM requires UART or rs232?
You should also be aware that UART level may be 3.2V or 5V aware. Checks specs of GSM module.

It is 5v level.
 

if you are using RX ,Tx pin direct to PIC your connection should be like

Tx(gsm)--->Rx(PIC)
Rx(gsm)---->Tx(PIC)
gnd(gsm)---->gnd(PIC)

then you can communicate.
 

check your baud rate and clock setting in fuse bits setting.your gsm and PIC might be different.

Try to make gsm in auto baud rate setting.
 

As you are stated the connections seems fine. Check for the GSM module gets proper power and also check for the status LED's which is getting proper signal and then only GSM can able to communicate.

If above mentioned things are verified and if you found everything is fine then carry out the below points.

Generally for few new GSM modules the baud rate will be in 115200. So in that case you need to set to 115200 in teraterm & try to communicate. If it works out then try to set the baud rate to 9600 and save it. It could work out.
 

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