Unable to read data from RTC DS1307 using Atmega8 and mikroc.

[djc]

Hello all,

i am designing a home potted plant watering system. For this i am using RTC DS1307 , ATMEGA8 and mikroc. I am trying to read the data from RTC. Though i am able to write the data to RTC but i believe it's could't read it back means while data is displayed on an LCD neither date nor time is getting updated . Please guide me on this. Code is as follows.

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Code C - [expand]
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// Software I2C connections
sbit Soft_I2C_Scl_Output    at PORTC5_bit;
sbit Soft_I2C_Sda_Output    at PORTC4_bit;
sbit Soft_I2C_Scl_Input     at PINC5_bit;
sbit Soft_I2C_Sda_Input     at PINC4_bit;
sbit Soft_I2C_Scl_Direction at DDC5_bit;
sbit Soft_I2C_Sda_Direction at DDC4_bit;
// End Software I2C connections
 
// LCD module connections
sbit LCD_RS at PORTD4_bit;
sbit LCD_EN at PORTD3_bit;
sbit LCD_D4 at PORTD5_bit;
sbit LCD_D5 at PORTD6_bit;
sbit LCD_D6 at PORTD7_bit;
sbit LCD_D7 at PORTB0_bit;
 
sbit LCD_RS_Direction at DDD4_bit;
sbit LCD_EN_Direction at DDD3_bit;
sbit LCD_D4_Direction at DDD5_bit;
sbit LCD_D5_Direction at DDD6_bit;
sbit LCD_D6_Direction at DDD7_bit;
sbit LCD_D7_Direction at DDB0_bit;
// End LCD module connections
 
int seconds=00,minutes=19,hours=12,day=04,date=18,month=07,year=9;
unsigned char x1,y1;
char welcome=1,time=1;
 
void welcome_msg(){
                /*Lcd_Out(1,1, "Welcome");
                Delay_ms(100);
                Lcd_Out(1,9, "To");
                Delay_ms(100);
                Lcd_Out(1,12, "SMART");
                Delay_ms(100);
                Lcd_Out(2,1, "Home");
                Delay_ms(100);
                Lcd_Out(2,6, "Irrigation");
                Delay_ms(2000);*/
                Lcd_Cmd(_LCD_CLEAR);
                LCD_Out(1,1,"Date:  :  :");      //' Prepare and output static text on LCD
                Delay_ms(10);
                LCD_Out(2,1,"Time:  :  :");
                Delay_ms(10);
 
                LCD_Out(1,12,"201");
                //Lcd_Cmd(_LCD_CLEAR);
}
 
void RTC_Write()
{        seconds = Dec2Bcd (seconds);
         hours   = Dec2Bcd (hours);
         minutes = Dec2Bcd (minutes);
         day     = Dec2Bcd (day);
         date    = Dec2Bcd (date);
         month   = Dec2Bcd (month);
         year    = Dec2Bcd (year);
        
         Soft_I2C_Start();
         Soft_I2C_Write(0xD1);
         Soft_I2C_Write(0x00);
         Soft_I2C_Stop();
 
         Soft_I2C_Start();
         Soft_I2C_Write(0xD0);
         Soft_I2C_Write(0x00);
 
         Soft_I2C_Write(0x00);    // Sec
         Soft_I2C_Write(seconds);    // Sec
         Soft_I2C_Write(minutes);  // min
         Soft_I2C_Write(hours);   //Hour
 
         Soft_I2C_Write(0x01);   //week
         //Soft_I2C_Write(0x03);   //week
         Soft_I2C_Write(day);   //day
         //Soft_I2C_Write(date);  //date
         Soft_I2C_Write(Month); //month
         Soft_I2C_Write(Year);  //year
         Soft_I2C_Write(0x90);
         Soft_I2C_Stop();
        Delay_ms(5);
 
}
 
void RTC_Read(){
        Soft_I2C_Start();
        Soft_I2C_Write(0xD0);
        Soft_I2C_Write(0);
        Soft_I2C_Start();
        Soft_I2C_Write(0xD1);
        seconds=Soft_I2C_Read(1);
        seconds = Bcd2Dec(seconds);
        minutes=Soft_I2C_Read(1);
        minutes = Bcd2Dec(minutes);
        hours=Soft_I2C_Read(1);
        hours = Bcd2Dec(hours);
        day=Soft_I2C_Read(1);
        day = Bcd2Dec(day);
        date=Soft_I2C_Read(1);
        date = Bcd2Dec(date);
        month=Soft_I2C_Read(1);
        month = Bcd2Dec(month);
        year=Soft_I2C_Read(1);
        year = Bcd2Dec(year);
        Soft_I2C_Read(0);
        Soft_I2C_Stop();         //' Issue stop signal}
        Delay_ms(20);
}
 
void Display_Time(){
   Lcd_Chr(1, 6, (day / 10)   + 48);    //' Print tens digit of day variable
   Lcd_Chr(1, 7, (day % 10)   + 48);  //' Print oness digit of day variable
   Lcd_Chr(1, 9, (month / 10) + 48);
   Lcd_Chr(1,10, (month % 10) + 48);
   Lcd_Chr(1,15,  year        + 48);     //'56 Print year vaiable + 8 (start from year 2008)*/
   Lcd_Chr(2, 6, (hours / 10)   + 48);
   Lcd_Chr(2, 7, (hours % 10)   + 48);
   Lcd_Chr(2, 9, (minutes / 10) + 48);
   Lcd_Chr(2,10, (minutes % 10) + 48);
   Lcd_Chr(2,12, (seconds / 10) + 48);
   Lcd_Chr(2,13, (seconds % 10) + 48);
}
void main() {
 //RTC_Init();
 Soft_I2C_Init();
 Delay_ms(5);
 Lcd_Init();
 Delay_ms(10);
 Lcd_Cmd(_LCD_CLEAR);
 Delay_ms(10);
                while(1){
                if(welcome==1){
                welcome_msg();
                RTC_Write();
                welcome=0;
                }
 
                RTC_Read();
                //Transform_Time();      //' Format date and time
                Display_Time();        //' Prepare and display on LCD
 
                }
}

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I am using Software I2C library in mikroc.

 

[baileychic]

I don't see the code of TransformTime() function. TransformTime() is needed to convert the RTC data to readable form. libstock.com has the mikroE example code for the DS1307.

 

[andre_luis]

neither date nor time is getting updated

I can't see in your code the 7^th bit of Address 00h (CH) being set anywhere, which should be done at least once after DS1307 got powered. It is responsible for effectively starting the RTC peripheral, review datasheet.



[EDIT]

As paulfujo warned on post #10, this bit should be cleared !!!

 

[djc]

Thanks for the reply baileychic . But job of transformation i.e to convert data from BCD to Decimal has been done in RTC_Read function itself

- - - Updated - - -

Thanx Andre sir. However i have written "Soft_I2C_Write(0x00);" in RTC_Write() function. Is it wrong? Is it not working as it should be.

 

[andre_luis]

In the line 125 there is this function, disabled:

//RTC_Init();

Which certainly should be some routine for checking and ensuring that the clock would be always running, by resetting bit 7 of the address 0x00, if were not. Another option could be something like that (note that regardless previous value of 7th bit, it forces to '0' asserting oscillator enabled without clearing 'seconds' register):

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Code C - [expand]
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void RTC_Init(){
    int seconds=0;
 
    Soft_I2C_Start();
    Soft_I2C_Write(0xD0);      // DS1307 address
    Soft_I2C_Write(0x00);      // REG 0 -> seconds
    Soft_I2C_Start();
    Soft_I2C_Write(0xD1);      // RD from RTC
    seconds = Bcd2Dec(Soft_I2C_Read(0)); // Read current "seconds" in DS1307
    Soft_I2C_Stop();
 
    seconds = (seconds & 0x7F);  // ensure bit CH is disabled -> enable Oscillator
 
    Delay_ms(50);
 
    Soft_I2C_Start();
    Soft_I2C_Write(0xD0);      // WR to RTC
    Soft_I2C_Write(0x00);      // REG 0 -> seconds
    Soft_I2C_Write(Dec2Bcd(seconds));     // Start oscillator with current "seconds value
    Soft_I2C_Start();
    Soft_I2C_Write(0xD0);      // WR to RTC
    Soft_I2C_Write(0x07);      // Control Register
    Soft_I2C_Write(0x80);      // Disable squarewave output pin
    Soft_I2C_Stop();
}

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[djc]

Thank you for the suggestion sir, however i had used "Soft_I2C_Init();". I thought it will do the job for me though. This is the output on LCD
Date: 20:07:2019
Time: 12:38:00

 

[djc]

Thanks for all the help Andre sir, issue was something different. Some loose connection was there from RTC to micro controller. Little re soldering is done and now i am able to read the values back from RTC and values are getting updated too.

 

[andre_luis]

however i had used "Soft_I2C_Init();". I thought it will do the job for me though.

Just to let you know: Soft_I2C_Init() has a different purpose, it is intended to enable the I2C bus from microcontroller`s (master) side, whereas RTC_init() would enable the DS1307 (slave) throught the just activated I2C bus; surely there are some forgotten steps you have done previously, aside of the code above to effectively enable the DS1307 device; by default its oscillator is disabled at power up.

 

[djc]

That's the great piece of information sir. Thank you for nice guidance.

 

[paulfjujo]

hello,

don't forget , put ZERo to enable oscillator, not ONE !
a good way to test if RTC is initialised is to connect a led + R on SQWE RTC Ouput
the led will blink every seconde (1Hz)
and correct data must written inside the RTC to get after , correct information reading.

        write_ds1307(0,0x00); //Reset second to 0 sec. and Enable Oscillator
        write_ds1307(1,Dec2Bcd(minute)); //write min
        write_ds1307(2,Dec2Bcd(heure)); //write hour
        write_ds1307(3,Dec2Bcd(jS)); //write day of week
        write_ds1307(4,Dec2Bcd(jour)); // write date
        write_ds1307(5,Dec2Bcd(mois)); // write month
        write_ds1307(6,Dec2Bcd(Annee)); // write year 2014

      write_ds1307(7,0x10); // Sortie SQW   1Hz
       //  write_ds1307(7,0x11); // Sortie SQW   4096 Hz
      //  write_ds1307(7,0x12); // Sortie SQW   8192 Hz
       // write_ds1307(7,0x13); // Sortie SQW   32768 Hz

 

[andre_luis]

don't forget , put ZERo to enable oscillator, not ONE !

Thanks for the warning, I will correct the code suggested above.