I want modulate this code ( interfacing at89c51 with gsm )

Hi

In my project will be there two switches. One for send AT to gsm to make sure the gsm is work and switch number two when it's 1 will send AT commands to send a message to a specific number.

Now I'll explain more.

see this link .. HERE

I'll use this circuit, in P1.6 here will be switch if 1 it will send AT to gsm ounce after that I want the response show on LCD.
And in P1.7 another switch, if 1 send AT+CMGF=1 then show response on lcd , then send AT+CMGW="+*********", then send a written message example "Hi".
See this link .. HERE

Code is here .. OPEN

// Program to Interface GSM Module with 8051 microcontroller (AT89C51) without using PC

#include#define port P1
#define dataport P2 // Data port for LCD
sbit rs = port^2;
sbit rw = port^3;
sbit en = port^4;
int count,i;
unsigned char check,str[15];
bit check_space;

void init_serial() // Initialize serial port
{ TMOD=0x20; // Mode2 TH1=0xfd; // 9600 baud SCON=0x50; // Serial mode=1 ,8-Bit data,1 Stop bit ,1 Start bit, Receiving on TR1=1; // Start timer
} void delay(unsigned int msec) // Function for delay
{ int i,j; for(i=0;i}

void lcd_cmd(unsigned char item) // Function to send command on LCD
{ dataport = item; rs= 0; rw=0; en=1; delay(1); en=0; return;
}

void lcd_data(unsigned char item) // Function to display character on LCD
{ dataport = item; rs= 1; rw=0; en=1; delay(1); en=0; return;
}

void lcd_data_string(unsigned char *str) // Function to display string on LCD
{ int i=0; while(str[i]!='\0') { lcd_data(str[i]); i++; delay(10); } return;
} void lcd()
{ lcd_cmd(0x38); // For using 8-bit 2 row LCD delay(5); lcd_cmd(0x0F); // For display on cursor blinking delay(5); lcd_cmd(0x80); // Set the cursor on first position of LCD delay(5);
}

void transmit_data(unsigned char str) // Function to transmit data through serial port
{ SBUF=str; //Store data in SBUF while(TI==0); //Wait till data transmits TI=0;
}

void receive_data() interrupt 4 // Function to recieve data serialy from RS232 into microcontroller { RI=0; str[++count]=SBUF; //Read SBUF

}

unsigned char byte_check() // Function to check carraige return and new line character
{ switch(str[0]) { case 0x0a: { // Return 0x00 for new line return 0x00; break ; } case 0x0d: { // Return 0x01 for carriage return return 0x01; break ; } default :return 0x02 ; // Return 0x02 for characters except new line and carriage return }
}

void main()
{ lcd(); // Initialize LCD init_serial(); // Initialize serial port count=(-1); delay(500); lcd_data_string("Ready"); delay(10); lcd_cmd(0x01); IE=0x94; transmit_data('A'); // Transmit 'A' to serial port delay(1); transmit_data('T'); // Transmit 'T' to serial port delay(1); transmit_data(0x0d); // Transmit carriage return to serial port delay(50); while(1) { if(count>=0) { check=byte_check(); // Check the character if(check!=0x00) { if(check==0x01) { if(check_space==1) // Check previous character { lcd_data(0x20); check_space=0; } } else { lcd_data(str[0]); check_space=1; } } count--; for(i=0;i}

Hi..
Those links are not working.
Currently what error/issue you are facing.

Hi

how to include a switch with if statement ??

Please properly indent your code. It hard to understand your code like this.
something wrong, I found in your code. When using serial interrupt, you should know 8051 shares Tx and Rx interrupt. so whenever you send data over serial you get interrupt too.

instead of using TI bit, create a flag and use it. set that flag in ISR, e.g.

//this statement will change
while(TI==0);

//to
while(TI_flag == 0);

and you ISR should look like this:

void receive_data() interrupt 4
{
    if (RI)  {
        RI=0;
        str[++count]=SBUF; //Read SBUF
    } else {
        TI = 0;
        TI_flag = 1;
    }
}

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