Gsm modem interfacing with pic microcontroller
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The document discusses interfacing a GSM modem with a PIC microcontroller. Specifically, it describes how: 1) The author is able to send AT commands from the PIC to the GSM modem but is unable to receive the "OK" response from the modem back on the PIC. 2) The code provided initializes UART communication between the PIC and GSM modem to send AT commands and attempt to read responses, displaying status on an LCD screen. 3) It uses functions like Gsm_SMS_Init() to send the "AT" command and try to read the "OK" response in a loop, but is unable to receive the response on the PIC.
![sbit LCD_D5_Direction at TRISB1_bit;
sbit LCD_D6_Direction at TRISB2_bit;
sbit LCD_D7_Direction at TRISB3_bit;
// End LCD module connections
unsigned char ch; //
char Receive;
unsigned int adc_rd; // Declare variables
char *text; //
long tlong; //
unsigned int i,j;
char return_gsm[2];
char Gsm_Receive[100];
char Gsm_Msg[10];
char uart_rd[]="AT";
char uart_rd1[]="AT +CMGF=1";
char uart_rd2[]="AT +CMGR=1" ;
char uart_rd3[]="AT +CMGS=";
char Mobile_No[]="+919444721638" ;
char Send_Msg[]="@ON";
void main()
{
INTCON = 0; // All interrupts disabled
ADCON1 = 0x82; // A/D voltage reference is VCC
TRISA = 0xFF; // All port A pins are configured as inputs
TRISC=0x01;
Delay_ms(2000); // Rest of pins are configured as digital
UART1_Init(9600); // Initialize UART module at 9600 bps
Delay_ms(100); // Wait for UART module to stabilize
Lcd_Init(); // LCD display initialization
Lcd_Cmd(_LCD_CURSOR_OFF); // LCD command (cursor off)
Lcd_Cmd(_LCD_CLEAR); // LCD command (clear LCD)
text = "Air Pollution "; // Define the first message
Lcd_Out(1,1,text); // Write the first message in the first line
delay_ms(500);
text = "Sensor Value"; // Define the second message
Lcd_Out(2,1,text); // Define the first message
delay_ms(500);
Lcd_Cmd(_LCD_CLEAR);
text = "GSM"; // Define the third message
while (1)
{](https://image.slidesharecdn.com/gsmmodeminterfacingwithpicmicrocontroller-150510194716-lva1-app6891/85/Gsm-modem-interfacing-with-pic-microcontroller-2-320.jpg)
![Lcd_Out(1,1,text); // Define the first message
delay_ms(500);
Lcd_Cmd(_LCD_CLEAR);
Gsm_SMS_Init();
}
}
void Gsm_SMS_Init()
{
if (UART1_Tx_Idle() == 1)
{
for(i=0;i<=1;i++)
{
UART1_Write(uart_rd); //AT
}
UART1_Write(0x0D); //Enter
Lcd_Out(2,1,"AT"); // Define the first message
delay_ms(500);
Lcd_Cmd(_LCD_CLEAR);
//delay_ms(5000);
while(1)
{
if (UART1_Data_Ready())
{ // If data is received,
for(i=0;i<=1;i++)
{
return_gsm = UART1_Read(); // read the received data, Received OK
}
Lcd_Out(2,1,"OK"); // Define the first message
delay_ms(500);
Lcd_Cmd(_LCD_CLEAR);
/* UART1_Write(return_gsm[0]);
Lcd_Out(2,1,"OK RESEND"); // Define the first message
delay_ms(500);
Lcd_Cmd(_LCD_CLEAR); */
// UART1_Write(return_gsm[1]);
}
}
/*if(return_gsm[0]==0x4F && return_gsm[1]==0x4B)
{
if (UART1_Tx_Idle() == 1)
{
for(i=0;i<=8;i++)](https://image.slidesharecdn.com/gsmmodeminterfacingwithpicmicrocontroller-150510194716-lva1-app6891/85/Gsm-modem-interfacing-with-pic-microcontroller-3-320.jpg)
![unsigned char ch; //
char Receive;
unsigned int adc_rd; // Declare variables
char *text; //
long tlong; //
unsigned int i,j;
char return_gsm[2];
char Gsm_Receive[100];
char Gsm_Msg[10];
char uart_rd[]="AT";
char uart_rd1[]="AT+CMGF=1";
char uart_rd2[]="AT+CMGR=1" ;
char uart_rd3[]="AT+CMGS=";
char Mobile_No[]="+919444721638" ;
char Send_Msg[]="@ON";
void main()
{
INTCON = 0; // All interrupts disabled
ADCON1 = 0x82; // A/D voltage reference is VCC
TRISA = 0xFF; // All port A pins are configured as inputs
TRISC=0x80;
Delay_ms(2000); // Rest of pins are configured as digital
UART1_Init(9600); // Initialize UART module at 9600 bps
Delay_ms(100); // Wait for UART module to stabilize
Lcd_Init(); // LCD display initialization
Lcd_Cmd(_LCD_CURSOR_OFF); // LCD command (cursor off)
Lcd_Cmd(_LCD_CLEAR); // LCD command (clear LCD)
text = "Air Pollution "; // Define the first message
Lcd_Out(1,1,text); // Write the first message in the first line
delay_ms(500);
text = "Sensor Value"; // Define the second message
Lcd_Out(2,1,text); // Define the first message
delay_ms(500);
Lcd_Cmd(_LCD_CLEAR);
text = "GSM"; // Define the third message
while (1)
{
Lcd_Out(1,1,text); // Define the first message
delay_ms(500);
Lcd_Cmd(_LCD_CLEAR);
Gsm_SMS_Init();
}
}
void Gsm_SMS_Init()
{
if (UART1_Tx_Idle() == 1)
{
Lcd_Out(2,1,"AT"); // Define the first message
delay_ms(500);
Lcd_Cmd(_LCD_CLEAR);](https://image.slidesharecdn.com/gsmmodeminterfacingwithpicmicrocontroller-150510194716-lva1-app6891/85/Gsm-modem-interfacing-with-pic-microcontroller-5-320.jpg)
![for(i=0;i<=1;i++)
{
UART1_Write(uart_rd[i]); //AT
}
UART1_Write(0x0D); //Enter
//delay_ms(5000);
while(1)
{
Lcd_Out(2,1,"In while"); // Define the first message
delay_ms(500);
Lcd_Cmd(_LCD_CLEAR);
if (UART1_Data_Ready())
{ // If data is received,
Lcd_Out(2,1,"In IF"); // Define the first message
delay_ms(500);
Lcd_Cmd(_LCD_CLEAR);
for(i=0;i<=1;i++)
{
return_gsm[i] = UART1_Read(); // read the received data, Received
OK
}
Lcd_Out(2,1,"OK"); // Define the first message
delay_ms(500);
Lcd_Cmd(_LCD_CLEAR);
/* UART1_Write(return_gsm[0]);
Lcd_Out(2,1,"OK RESEND"); // Define the first message
delay_ms(500);
Lcd_Cmd(_LCD_CLEAR); */
// UART1_Write(return_gsm[1]);
}
}
/*if(return_gsm[0]==0x4F && return_gsm[1]==0x4B)
{
if (UART1_Tx_Idle() == 1)
{
for(i=0;i<=8;i++)
{
UART1_Write(uart_rd1[i]); //AT+CMGF=1
}
UART1_Write(0x0D); //Enter
Lcd_Out(1,1,"AT+CMGF=1");
delay_ms(500);
Lcd_Cmd(_LCD_CLEAR);
}
if (UART1_Data_Ready())
{ // If data is received,
for(i=0;i<=1;i++)
{
return_gsm[i] = UART1_Read(); // read the received data,OK](https://image.slidesharecdn.com/gsmmodeminterfacingwithpicmicrocontroller-150510194716-lva1-app6891/85/Gsm-modem-interfacing-with-pic-microcontroller-6-320.jpg)
![}
Lcd_Out(2,1,"Received OK");
delay_ms(500);
Lcd_Cmd(_LCD_CLEAR);
}
} */
}
}
Code (text):
void sms_send();
void sms_del();
void sms_read();
char sms[11];
char output[65];
unsigned char* MSG4 = "AT+CNMI=2,1,0,0,0";
void main() {
UART1_Init(9600); // Initialize UART module at 9600 bps
Delay_ms(100); // Wait for UART module to stabilize
// sms_del();
sms_read();
}
void sms_send()
{
int i;
/*UART1_Write_Text("ATnr");
delay_ms(500);
UART1_Write_Text("AT+CMGF=1nr");
delay_ms(500); */
UART1_Write_Text("AT+CMGS=");
UART1_Write(0x22);
UART1_Write_Text("+919444721638");
UART1_Write(0x22);
UART1_Write_Text("nr");
delay_ms(500);
for(i=0;i<64;i++)
{
if(output[i]=='0') break;//ask for null character of sms vector when find it go out
of for() loop
UART1_Write(sms[i]);
}
delay_ms(500);
UART1_Write(26);// send ctrl + Z
return;
}
void sms_del()
{
UART1_Write_Text("AT+CMGD=1nr");
delay_ms(500);
}](https://image.slidesharecdn.com/gsmmodeminterfacingwithpicmicrocontroller-150510194716-lva1-app6891/85/Gsm-modem-interfacing-with-pic-microcontroller-7-320.jpg)
![void sms_read()
{
int i;
//char sms[11];
UART1_Write_Text("ATnr");
delay_ms(500);
UART1_Write_Text(MSG4); //cpms
Delay_ms(1000);
UART1_Write(0X0D); // ENTER
Delay_ms(1000);
UART1_Write_Text("AT+CMGF=1nr");
delay_ms(500);
UART1_Write_Text("AT+CMGR=7nr");
//delay_ms(500);
while (UART1_Data_Ready() != 1);
UART1_Read_Text(output, "OK", 65); // reads text until 'OK' is found
sms_send();
//return;
}](https://image.slidesharecdn.com/gsmmodeminterfacingwithpicmicrocontroller-150510194716-lva1-app6891/85/Gsm-modem-interfacing-with-pic-microcontroller-8-320.jpg)
Gsm modem interfacing with pic microcontroller
- 1. GSM Modem Interfacing with PIC Microcontroller Hi to all... I am doing a project in which i will be interfacing a gsm modem with PIC microcontroller(16f877).. when i connect the gsm modem with PC i can able to send and read the messages in the sim using AT commands in hyperterminal...Then i iniatized UART in PIC send and received data to PC through hyperterminal its working properly... When i interfaced PIC with GSM Modem i can able to send AT command to GSM modem but the reply "OK " from GSM modem to PIC is not received by PIC... Example: AT (Enter)-----In Hyperterminal OK ------Message from GSM Modem Compiler:MikroC Baud Rate:9600 bps GSM MOdem:Wavecom HT-W2101 I can able to send AT and Enter command from UART to PIC... But i cant able see the reply from GSM modem... but it works well when i interface GSM modem with PC hyperterminal... Help me... /*Header***************************************************** Microcontroller=16f877 Clock=10 Mhz Project Title:Air Pollution Control Using GSM/GPRS Developed By:Sathiesh Kumar.V Date:31/01/2010*/ void Calculation(unsigned int ) ; void Gsm_SMS_Init(); void Gsm_SMS_Read(); void Gsm_SMS_Send(); // LCD module connections sbit LCD_RS at RB4_bit; sbit LCD_EN at RB5_bit; sbit LCD_D4 at RB0_bit; sbit LCD_D5 at RB1_bit; sbit LCD_D6 at RB2_bit; sbit LCD_D7 at RB3_bit; sbit LCD_RS_Direction at TRISB4_bit; sbit LCD_EN_Direction at TRISB5_bit; sbit LCD_D4_Direction at TRISB0_bit;
- 2. sbit LCD_D5_Direction at TRISB1_bit; sbit LCD_D6_Direction at TRISB2_bit; sbit LCD_D7_Direction at TRISB3_bit; // End LCD module connections unsigned char ch; // char Receive; unsigned int adc_rd; // Declare variables char *text; // long tlong; // unsigned int i,j; char return_gsm[2]; char Gsm_Receive[100]; char Gsm_Msg[10]; char uart_rd[]="AT"; char uart_rd1[]="AT +CMGF=1"; char uart_rd2[]="AT +CMGR=1" ; char uart_rd3[]="AT +CMGS="; char Mobile_No[]="+919444721638" ; char Send_Msg[]="@ON"; void main() { INTCON = 0; // All interrupts disabled ADCON1 = 0x82; // A/D voltage reference is VCC TRISA = 0xFF; // All port A pins are configured as inputs TRISC=0x01; Delay_ms(2000); // Rest of pins are configured as digital UART1_Init(9600); // Initialize UART module at 9600 bps Delay_ms(100); // Wait for UART module to stabilize Lcd_Init(); // LCD display initialization Lcd_Cmd(_LCD_CURSOR_OFF); // LCD command (cursor off) Lcd_Cmd(_LCD_CLEAR); // LCD command (clear LCD) text = "Air Pollution "; // Define the first message Lcd_Out(1,1,text); // Write the first message in the first line delay_ms(500); text = "Sensor Value"; // Define the second message Lcd_Out(2,1,text); // Define the first message delay_ms(500); Lcd_Cmd(_LCD_CLEAR); text = "GSM"; // Define the third message while (1) {
- 3. Lcd_Out(1,1,text); // Define the first message delay_ms(500); Lcd_Cmd(_LCD_CLEAR); Gsm_SMS_Init(); } } void Gsm_SMS_Init() { if (UART1_Tx_Idle() == 1) { for(i=0;i<=1;i++) { UART1_Write(uart_rd); //AT } UART1_Write(0x0D); //Enter Lcd_Out(2,1,"AT"); // Define the first message delay_ms(500); Lcd_Cmd(_LCD_CLEAR); //delay_ms(5000); while(1) { if (UART1_Data_Ready()) { // If data is received, for(i=0;i<=1;i++) { return_gsm = UART1_Read(); // read the received data, Received OK } Lcd_Out(2,1,"OK"); // Define the first message delay_ms(500); Lcd_Cmd(_LCD_CLEAR); /* UART1_Write(return_gsm[0]); Lcd_Out(2,1,"OK RESEND"); // Define the first message delay_ms(500); Lcd_Cmd(_LCD_CLEAR); */ // UART1_Write(return_gsm[1]); } } /*if(return_gsm[0]==0x4F && return_gsm[1]==0x4B) { if (UART1_Tx_Idle() == 1) { for(i=0;i<=8;i++)
- 4. { UART1_Write(uart_rd1); //AT+CMGF=1 } UART1_Write(0x0D); //Enter Lcd_Out(1,1,"AT+CMGF=1"); delay_ms(500); Lcd_Cmd(_LCD_CLEAR); } if (UART1_Data_Ready()) { // If data is received, for(i=0;i<=1;i++) { return_gsm = UART1_Read(); // read the received data,OK } Lcd_Out(2,1,"Received OK"); delay_ms(500); Lcd_Cmd(_LCD_CLEAR); } } */ } } Code (text): /*Header***************************************************** Microcontroller=16f877 Clock=10 Mhz Project Title:Air Pollution Control Using GSM/GPRS Developed By:Sathiesh Kumar.V Date:31/01/2010*/ void Calculation(unsigned int ) ; void Gsm_SMS_Init(); void Gsm_SMS_Read(); void Gsm_SMS_Send(); // LCD module connections sbit LCD_RS at RB4_bit; sbit LCD_EN at RB5_bit; sbit LCD_D4 at RB0_bit; sbit LCD_D5 at RB1_bit; sbit LCD_D6 at RB2_bit; sbit LCD_D7 at RB3_bit; sbit LCD_RS_Direction at TRISB4_bit; sbit LCD_EN_Direction at TRISB5_bit; sbit LCD_D4_Direction at TRISB0_bit; sbit LCD_D5_Direction at TRISB1_bit; sbit LCD_D6_Direction at TRISB2_bit; sbit LCD_D7_Direction at TRISB3_bit; // End LCD module connections
- 5. unsigned char ch; // char Receive; unsigned int adc_rd; // Declare variables char *text; // long tlong; // unsigned int i,j; char return_gsm[2]; char Gsm_Receive[100]; char Gsm_Msg[10]; char uart_rd[]="AT"; char uart_rd1[]="AT+CMGF=1"; char uart_rd2[]="AT+CMGR=1" ; char uart_rd3[]="AT+CMGS="; char Mobile_No[]="+919444721638" ; char Send_Msg[]="@ON"; void main() { INTCON = 0; // All interrupts disabled ADCON1 = 0x82; // A/D voltage reference is VCC TRISA = 0xFF; // All port A pins are configured as inputs TRISC=0x80; Delay_ms(2000); // Rest of pins are configured as digital UART1_Init(9600); // Initialize UART module at 9600 bps Delay_ms(100); // Wait for UART module to stabilize Lcd_Init(); // LCD display initialization Lcd_Cmd(_LCD_CURSOR_OFF); // LCD command (cursor off) Lcd_Cmd(_LCD_CLEAR); // LCD command (clear LCD) text = "Air Pollution "; // Define the first message Lcd_Out(1,1,text); // Write the first message in the first line delay_ms(500); text = "Sensor Value"; // Define the second message Lcd_Out(2,1,text); // Define the first message delay_ms(500); Lcd_Cmd(_LCD_CLEAR); text = "GSM"; // Define the third message while (1) { Lcd_Out(1,1,text); // Define the first message delay_ms(500); Lcd_Cmd(_LCD_CLEAR); Gsm_SMS_Init(); } } void Gsm_SMS_Init() { if (UART1_Tx_Idle() == 1) { Lcd_Out(2,1,"AT"); // Define the first message delay_ms(500); Lcd_Cmd(_LCD_CLEAR);
- 6. for(i=0;i<=1;i++) { UART1_Write(uart_rd[i]); //AT } UART1_Write(0x0D); //Enter //delay_ms(5000); while(1) { Lcd_Out(2,1,"In while"); // Define the first message delay_ms(500); Lcd_Cmd(_LCD_CLEAR); if (UART1_Data_Ready()) { // If data is received, Lcd_Out(2,1,"In IF"); // Define the first message delay_ms(500); Lcd_Cmd(_LCD_CLEAR); for(i=0;i<=1;i++) { return_gsm[i] = UART1_Read(); // read the received data, Received OK } Lcd_Out(2,1,"OK"); // Define the first message delay_ms(500); Lcd_Cmd(_LCD_CLEAR); /* UART1_Write(return_gsm[0]); Lcd_Out(2,1,"OK RESEND"); // Define the first message delay_ms(500); Lcd_Cmd(_LCD_CLEAR); */ // UART1_Write(return_gsm[1]); } } /*if(return_gsm[0]==0x4F && return_gsm[1]==0x4B) { if (UART1_Tx_Idle() == 1) { for(i=0;i<=8;i++) { UART1_Write(uart_rd1[i]); //AT+CMGF=1 } UART1_Write(0x0D); //Enter Lcd_Out(1,1,"AT+CMGF=1"); delay_ms(500); Lcd_Cmd(_LCD_CLEAR); } if (UART1_Data_Ready()) { // If data is received, for(i=0;i<=1;i++) { return_gsm[i] = UART1_Read(); // read the received data,OK
- 7. } Lcd_Out(2,1,"Received OK"); delay_ms(500); Lcd_Cmd(_LCD_CLEAR); } } */ } } Code (text): void sms_send(); void sms_del(); void sms_read(); char sms[11]; char output[65]; unsigned char* MSG4 = "AT+CNMI=2,1,0,0,0"; void main() { UART1_Init(9600); // Initialize UART module at 9600 bps Delay_ms(100); // Wait for UART module to stabilize // sms_del(); sms_read(); } void sms_send() { int i; /*UART1_Write_Text("ATnr"); delay_ms(500); UART1_Write_Text("AT+CMGF=1nr"); delay_ms(500); */ UART1_Write_Text("AT+CMGS="); UART1_Write(0x22); UART1_Write_Text("+919444721638"); UART1_Write(0x22); UART1_Write_Text("nr"); delay_ms(500); for(i=0;i<64;i++) { if(output[i]=='0') break;//ask for null character of sms vector when find it go out of for() loop UART1_Write(sms[i]); } delay_ms(500); UART1_Write(26);// send ctrl + Z return; } void sms_del() { UART1_Write_Text("AT+CMGD=1nr"); delay_ms(500); }
- 8. void sms_read() { int i; //char sms[11]; UART1_Write_Text("ATnr"); delay_ms(500); UART1_Write_Text(MSG4); //cpms Delay_ms(1000); UART1_Write(0X0D); // ENTER Delay_ms(1000); UART1_Write_Text("AT+CMGF=1nr"); delay_ms(500); UART1_Write_Text("AT+CMGR=7nr"); //delay_ms(500); while (UART1_Data_Ready() != 1); UART1_Read_Text(output, "OK", 65); // reads text until 'OK' is found sms_send(); //return; }