How to read Current GSM TIME and Date using AT command

GSM Network time synchronization for RTC using AT+CLTS command

Since I had started designing the VALTRACK GPS trackers, I have always had trouble with maintaining the correct time on the tracking device because once I remove the battery, the PIC RTC lost its synchronization. I didn’t have space or luxury to maintain a separate backup battery for the PIC RTC. 

So, I was only using the server time for the incoming packets where the time field was auto-populated by the server-side script.

This method was ok for certain applications but we didn’t have the method to know the delayed packets time (Which get re-sent later on failure). This is when I was looking for a method to calibrate and sync the MCU RTC to the right time on power-on reset. 

Sync using network time : 

We then implemented this method where in the GSM module synchronizes its internal RTC and then we take the clock value of the GSM module and set the clock of our PIC RTC

This method has been working fine so far as it doesn’t need any manual intervention for calibrating the time.  

Here are the commands I used: 

Command to read the GSM RTC clock : 

ATE1 Set Command Echo Mode

ATE1

ATI Display Product Identification Information

ATI

AT+CREG Network Registration

AT+CREG=1

AT+CSQ Signal Quality Report

AT+CSQ

AT+COPS Operator Selection

AT+COPS?

AT+CMGF Select SMS Message Format

AT+CMGF=1

AT+CCLK Clock

AT+CCLK?

AT+CLTS Get Local Timestamp

AT+CLTS=1

AT&W Store Active Profile

AT&W

Final code

/*
 * File:   main.c
 * Author: Devilal
 *
 * Created on 31 March 2021, 4:08 PM
 */

#define    FCY    10000000UL    // Instruction cycle frequency, Hz - required for __delayXXX() to work
#include "stdio.h"
#include "stdlib.h"
#include "string.h"
#include "libpic30.h"
#include "xc.h"

  

// CONFIG3
#pragma config WPFP = WPFP511           // Write Protection Flash Page Segment Boundary (Highest Page (same as page 85))
#pragma config WPDIS = WPDIS            // Segment Write Protection Disable bit (Segmented code protection disabled)
#pragma config WPCFG = WPCFGDIS         // Configuration Word Code Page Protection Select bit (Last page(at the top of program memory) and Flash configuration words are not protected)
#pragma config WPEND = WPENDMEM         // Segment Write Protection End Page Select bit (Write Protect from WPFP to the last page of memory)

// CONFIG2
#pragma config POSCMOD = XT             // Primary Oscillator Select (XT oscillator mode selected)
#pragma config IOL1WAY = ON             // IOLOCK One-Way Set Enable bit (Write RP Registers Once)
#pragma config OSCIOFNC = OFF           // Primary Oscillator Output Function (OSCO functions as CLKO (FOSC/2))
#pragma config FCKSM = CSDCMD           // Clock Switching and Monitor (Both Clock Switching and Fail-safe Clock Monitor are disabled)
#pragma config FNOSC = PRI              // Oscillator Select (Primary oscillator (XT, HS, EC))
#pragma config IESO = OFF                // Internal External Switch Over Mode (IESO mode (Two-speed start-up) enabled)

// CONFIG1
#pragma config WDTPS = PS32768          // Watchdog Timer Postscaler (1:32,768)
#pragma config FWPSA = PR128            // WDT Prescaler (Prescaler ratio of 1:128)
#pragma config WINDIS = OFF             // Watchdog Timer Window (Standard Watchdog Timer is enabled,(Windowed-mode is disabled))
#pragma config FWDTEN = OFF              // Watchdog Timer Enable (Watchdog Timer is enabled)
#pragma config ICS = PGx3               // Comm Channel Select (Emulator functions are shared with PGEC3/PGED3)
#pragma config GWRP = OFF               // General Code Segment Write Protect (Writes to program memory are allowed)
#pragma config GCP = OFF                // General Code Segment Code Protect (Code protection is disabled)
#pragma config JTAGEN = OFF             // JTAG Port Enable (JTAG port is disabled)
//void delay(int delay);

int gsm_index,uart2_index,uart3_index,uart4_index;
char gsm_buffer[100],uart2_buffer[100],uart3_buffer[100],uart4_buffer[100];
int gsm_year,gsm_month,gsm_date,gsm_hours,gsm_minutes,gsm_seconds;
char GSM_TIME_DATE[128];

char pkz[4]; 

void UART1Init(void)
{
//	U1BRG = 25;		// 9600 @ 8MHZ
	U1BRG = 32;		// 9600 @ 10MHZ

	U1MODEbits.UARTEN = 1;		// UART2 is Enabled
	
	U1MODEbits.USIDL = 0;		// Continue operation at Idlestate
	U1MODEbits.IREN = 0;		// IrDA En/Decoder is disabled
	U1MODEbits.RTSMD = 0;		// flow control mode
	U1MODEbits.UEN1 = 0b00;		// UTX, RTX, are enabled U1CTS, U1RTS are disabled
	U1MODEbits.UEN0 = 0b00;		// UTX, RTX, are enabled U1CTS, U1RTS are disabled
	U1MODEbits.WAKE = 1;		// Wake-up on start bit is enabled
	U1MODEbits.LPBACK = 0;		// Loop-back is disabled
	U1MODEbits.ABAUD = 0;		// auto baud is disabled
	U1MODEbits.RXINV = 0;		// No RX inversion
	U1MODEbits.BRGH = 0;		// low boud rate
	U1MODEbits.PDSEL = 0b00; 	// 8bit no parity
	U1MODEbits.STSEL = 0;		// one stop bit	


	U1STAbits.UTXISEL1 = 0b00;		
	U1STA &= 0xDFFF;			// clear TXINV by bit masking
	U1STAbits.UTXBRK = 0;		// sync break tx is disabled
	U1STAbits.UTXEN = 1;		//transmit  is enabled
	U1STAbits.URXISEL = 0b00;	// interrupt flag bit is set when RXBUF is filled whith 1 character
	U1STAbits.ADDEN = 0;		// address detect mode is disabled
	U1STAbits.RIDLE = 0;

	IPC2bits.U1RXIP = 7;        // sET uart1 Priority to 7
	IFS0bits.U1RXIF = 0;		// clear interrupt flag of rx
	IFS0bits.U1TXIF = 0;		// clear interrupt flag of rx
	IEC0bits.U1RXIE = 1;		// enable rx recieved data interrupt
	IEC0bits.U1TXIE = 0;
}
  void delay(int delay)
   {
       __delay_ms(delay/2);
   }


void UART4Init(void)
{
//	U4BRG = 25;					// 9600 
	U4BRG = 32;					// 9600 

	U4MODEbits.UARTEN = 1;		// UART2 is Enabled
	U4MODEbits.USIDL = 0;		// Continue operation at Idlestate
	U4MODEbits.IREN = 0;		// IrDA En/Decoder is disabled
	U4MODEbits.RTSMD = 0; 		// flow control mode
	U4MODEbits.UEN1 = 0b00;		// UTX, RTX, are enabled U2CTS, U2RTS are disabled
	U4MODEbits.UEN0 = 0b00;		// UTX, RTX, are enabled U2CTS, U2RTS are disabled
	U4MODEbits.WAKE = 1;		// Wake-up on start bit is enabled
	U4MODEbits.LPBACK = 0;		// Loop-back is disabled
	U4MODEbits.ABAUD = 0;		// auto baud is disabled
	U4MODEbits.RXINV = 0;		// No RX inversion
	U4MODEbits.BRGH = 0;		// low boud rate
	U4MODEbits.PDSEL = 0b00; 	// 8bit no parity
	U4MODEbits.STSEL = 0;		// one stop bit	
		

	U4STAbits.UTXISEL1 = 0b00;		
	U4STA &= 0xDFFF;			// clear TXINV by bit masking
	U4STAbits.UTXBRK = 0;		// sync break tx is disabled
	U4STAbits.UTXEN = 1;		//transmit  is enabled
	U4STAbits.URXISEL = 0b00;	// interrupt flag bit is set when RXBUF is filled whith 1 character
	U4STAbits.ADDEN = 0;		// address detect mode is disabled

	IPC22bits.U4RXIP = 7;        // sET uart1 Priority to 6
	IFS5bits.U4RXIF = 0;		// clear interrupt flag of rx
	IFS5bits.U4TXIF = 0;		// clear interrupt flag of rx
	IEC5bits.U4RXIE = 1;		// enAble rx recieved data interrupt
	IEC5bits.U4TXIE = 0;
}
void UART1TransmitByte(uint8_t tx_byte)
{
	U1TXREG = tx_byte;
	while(!(U1STAbits.TRMT))
	{
	}
}
void UART1TransmitString(uint8_t *tx_str, uint16_t size)
{
	
_CNIE = 0;
	uint8_t ch;
    int i=0;
   
    uint8_t temp = 0;
    while (temp++<size)
	{
		ch = *tx_str;
		U1TXREG = ch;
		while(!(U1STAbits.TRMT))
		{
		}
		tx_str++;
		for(i=0;i<200;i++)
		{

		}
	}
_CNIE = 1;
}

void UART4TransmitString(uint8_t *tx_str,uint16_t size)
{
_CNIE = 0;
	uint8_t ch,i=0;
    uart4_index = 0;
    uint8_t temp = 0;
  
    while (temp++<size)	
	{
		ch = *tx_str;
		U4TXREG = ch;
		while(!(U4STAbits.TRMT))
		{
		}
		tx_str++;
		for(i=0;i<200;i++)
		{

		}
	}
_CNIE = 1;
}
void __attribute__((interrupt,no_auto_psv)) _U1RXInterrupt()
{
	char ch;

	_U1RXIF = 0;
	ch = U1RXREG;
    
    gsm_buffer[gsm_index++]=ch;
    
    if(gsm_index>300)
    {
        gsm_index=0;
    }
}

void __attribute__((interrupt,no_auto_psv)) _U4RXInterrupt()
{
	char ch4;

	_U4RXIF = 0;
	ch4 = U4RXREG;
    
    uart4_buffer[uart4_index++]=ch4;
    
    if(uart4_index>500)uart4_index=0;

}


void gsm_power_key()
{
   delay(500);
   PORTBbits.RB15 = 0;
   __delay_ms(300);
   PORTBbits.RB15 = 1;
   __delay_ms(1000);
}

int gsm_cmd(uint8_t *atcmd,uint16_t delay1,int length) 
{
    memset(gsm_buffer,'\0',sizeof(gsm_buffer));
    gsm_index = 0;
    UART1TransmitString(atcmd,strlen(atcmd));
    uint16_t temp=0;
    while(gsm_index<length)
    {
        if(temp>=delay1)
        {
            UART4TransmitString(gsm_buffer,strlen(gsm_buffer));
            return 0;
        }
        delay(1);
        temp++;
    }
    UART4TransmitString(gsm_buffer,strlen(gsm_buffer));
}


void gsm_init()
{
    gsm_cmd("AT\r\n",100,8);   // //AT command
    gsm_cmd("ATE1\r\n",300,11); //Set Command Echo Mode
    gsm_cmd("ATI\r\n",300,27);  //Display Product Identification Information
    gsm_cmd("AT+CREG=1\r\n",300,27);  //Display Product Identification Information
    gsm_cmd("AT+CSQ\r\n",300,37);  // Signal Quality Report
    gsm_cmd("AT+COPS?\r\n",300,37);  // Operator Selection
    gsm_cmd("AT+CMGF=1\r\n",300,17);  // Select SMS Message Format
    gsm_cmd("AT+CPIN?\r\n",300,31);  // Check SIM PIN
    delay(500);
}



void gsm_time()
{
//  gsm_cmd("AT+CCLK=\"27/06/21,12:20:12-32\"\r\n", 300,50); 
    
    gsm_cmd("AT+CCLK?\r\n", 300,50);
    gsm_cmd("AT+CLTS=1\r\n",300,31);  // Get Local Timestamp
    gsm_cmd("AT&W\r\n",300,31);  // Get Local Timestamp
    gsm_cmd("AT+CCLK?\r\n", 300,50);
    delay(500);
    
	if(strstr((char *)gsm_buffer,"+CCLK:"))
 	{
        memset(pkz,'\0',4);
		sprintf(pkz,"%c%c",gsm_buffer[19],gsm_buffer[20]);
        gsm_year=(atoi(pkz));
        
        memset(pkz,'\0',4);
		sprintf(pkz,"%c%c",gsm_buffer[22],gsm_buffer[23]);
		gsm_month=(atoi(pkz));
        
        memset(pkz,'\0',4);
		sprintf(pkz,"%c%c",gsm_buffer[25],gsm_buffer[26]);
		gsm_date=(atoi(pkz));
        
        
        memset(pkz,'\0',4);
		sprintf(pkz,"%c%c",gsm_buffer[28],gsm_buffer[29]);
		gsm_hours=(atoi(pkz));
        
        memset(pkz,'\0',4);
		sprintf(pkz,"%c%c",gsm_buffer[31],gsm_buffer[32]);
		gsm_minutes=(atoi(pkz));
        
        memset(pkz,'\0',4);
		sprintf(pkz,"%c%c",gsm_buffer[34],gsm_buffer[35]);
		gsm_seconds=(atoi(pkz));
        UART4TransmitString("GSM Date & Time :",sizeof("GSM Date & Time :"));
        sprintf(GSM_TIME_DATE,"%02d.%02d.%02d : %02d/%02d/%02d\r\n",gsm_hours,gsm_minutes,gsm_seconds,gsm_date,gsm_month,gsm_year);
        UART4TransmitString(GSM_TIME_DATE,sizeof(GSM_TIME_DATE));
	}


}

int main(void) 
{
    gpio_init();
    gsm_power_key();
     delay(500);
    UART1Init();
    UART4Init();
    delay(500);
    UART4TransmitString("..............................\r\n",sizeof("..............................\r\n"));
    UART4TransmitString("Start Application1\r\n",sizeof("Start Application1\r\n"));
    UART4TransmitString("..............................\r\n",sizeof("..............................\r\n"));
    delay(10500); 
    while(1)
    {
    gsm_init();
    delay(5000);
    gsm_time();
    delay(1000);
    }
    return 0;
}

void gpio_init()
{
    OSCCON = 0x0000;
    OSCTUN = 0x0000;
    CLKDIV = 0x0000;
    //resetSource = RCON;
    RCON = 0x00;
    INTCON1bits.NSTDIS = 1;
    AD1PCFGL = 0xFF; //dISABLE ANALOG I/P'S
    //////// UART 1 /////////////
    
    RPINR18bits.U1RXR = 6; // Assign U1RXR to RP6
    _TRISB6 = 1; //CONFIGURE PIN TO I/P
    RPOR3bits.RP7R = 3; //Assign U1TX To Pin RP7
    _TRISB7 = 0; //CONFIGURE PIN TO O/P
    
     //////// UART 2 /////////////
    
    RPINR19bits.U2RXR = 8; // Assign U2RXR to RP8
    _TRISB8 = 1; //CONFIGURE PIN TO I/P
    RPOR4bits.RP9R = 5; //Assign U2TX To Pin RP9
    _TRISB9 = 0; //CONFIGURE PIN TO O/P

     //////// UART 3 /////////////
    
    RPINR17bits.U3RXR = 3; // Assign U3RXR to RP3
    _TRISD10 = 1; //CONFIGURE PIN TO I/P
    RPOR0bits.RP0R = 28; //Assign U3TX To Pin RP0
    _TRISB0 = 0; //CONFIGURE PIN TO O/P
    
    //////// UART 4 /////////////
    RPINR27bits.U4RXR = 23; // Assign U4RXR to RP23
    _TRISD2 = 1; //CONFIGURE PIN TO I/P
    RPOR12bits.RP24R = 30; //Assign U4TX To Pin RP24
    _TRISD1 = 0; //CONFIGURE PIN TO O/P
    
    CNPU1bits.CN9PUE = 1;
 
     _TRISB15 = 0; // for modem reset
    _TRISB13 = 0; // Relay 
   
}

problems

When you enter AT+CCLK? Your not getting updated time and date

If your getting like this means your network time is not updated 

What to do for that

  • There is only one solution to update your current live Time and Date from GSM(SIM800)
  • update your current date and time into gsm using the below command
  • After that, you get the updated Time and Date

AT+CCLK=”21/06/27,13:14:00+22″

  • But there is a problem with this update when you turn of the power you’re updated till will be zero
  • But in over code, we updated AT+CCLK=1 when we get local updated Time and Date at that time this time will update with respected new local time.
  • Because of some time AT+CCLK? take time to update local time.

Why it is not updating

  • Your AT+CCLK? not providing the current Date and Times because you don’t have proper signal strength.
  • On the other hand AT+COPS? Operator name not found in your gsm module check your AT+COPS?
  • in case you’re getting the operator name then your not going to face any kind of issue.

Output

video

You may also like...

Leave a Reply

Your email address will not be published. Required fields are marked *

%d bloggers like this: