Hello all,

I am trying to connect a 8051 with a DS1307 RTC. For the sake of testing the connection, I am fetching the unit value of the seconds and display it on a seven segement display. Unfortunately, i don't get the value right. Could you please let me know what i am doing wrong?

#include "Main.h"
#include "Hardware_Config.h"
#include "ds1307.h"
#include "Seven_Seg_Symbols.h"
#include <stdio.h>


//connect SDA and SCL to Port1.1 and Port1.0
#define SDA P1_1 
#define SCL P1_0


void main()
{

	//Start the clock
	tByte second;
	tByte FirstDigit;
	P2 = 0x00;
	tByte
	DS1307_startTimer();

	while(1)
	{
		second = DS1307_get(SEC);
		FirstDigit = second % 10;
		P2 = SevenSeg_DisplayNumber(FirstDigit);
	}
}

 

/**********************************************
* File: DS1307.H
* Defines the basic function required to interact with the DS1307
* using the i2c.h header
***********************************************/

#ifndef _DS1307_H
#define _DS1307_H



#include "i2c.h" /* Need i2c bus */
#define DS1307_ID 0xD0
#define SEC   0x00
#define MIN   0x01
#define HOUR  0x02
#define DATE  0x04
#define MONTH 0x05
#define YEAR  0x06

unsigned char DS1307_get(unsigned char addr)
{
	unsigned char ret;
	I2C_start();            /* Start i2c bus */
	I2C_write(DS1307_ID);   /* Connect to DS1307 */
	I2C_write(addr); /* Request RAM address on DS1307 */
	I2C_start(); /* Start i2c bus */
	I2C_write(DS1307_ID+1); /* Connect to DS1307 for Read */
	ret = I2C_read(); /* Receive data */
	I2C_stop(); /* Stop i2c bus */
	return ret;
}

void DS1307_settime(unsigned char hh, unsigned char mm, unsigned char ss)
{
	I2C_start();
	I2C_write(DS1307_ID); /* connect to DS1307 */
	I2C_write(0x00); /* Request RAM address at 00H */
	I2C_write(ss); /* Write sec on RAM address 00H */
	I2C_write(mm); /* Write min on RAM address 01H */
	I2C_write(hh); /* Write hour on RAM address 02H */
	I2C_stop();           /* Stop i2c bus */
}

void DS1307_setdate(unsigned char dd, unsigned char mm, unsigned char yy)
{
	I2C_start();
	I2C_write(DS1307_ID); /* connect to DS1307 */
	I2C_write(0x04); /* Request RAM address at 04H */
	I2C_write(dd); /* Write date on RAM address 04H */
	I2C_write(mm); /* Write month on RAM address 05H */
	I2C_write(yy); /* Write year on RAM address 06H */
	I2C_stop(); /* Stop i2c bus */
}

void DS1307_startTimer()
{
	I2C_start();
	I2C_write(DS1307_ID); /* connect to DS1307 */
	I2C_write(0x00); /* Request RAM address at 00H */
	I2C_write(0x80); /* Set CH bit ie. 7th bit og 0x00 to start timer*/
	I2C_stop();           /* Stop i2c bus */
}

#endif

 

/**************************
* File name: i2c.h
* I2C drivers in C51 
**************************/

#ifndef _I2C_H
#define _I2C_H

#define I2C_DELAY 0x0F /* For delay i2c bus */

void I2C_delay(void)
{
	unsigned char i;
	for(i=0; i<I2C_DELAY; i++);
}

void I2C_clock(void)
{
	I2C_delay();
	SCL = 1; /* Start clock */
	I2C_delay();
	SCL = 0; /* Clear SCL */
}

void I2C_start(void)
{
	if(SCL)
	SCL = 0; /* Clear SCL */
	SDA = 1; /* Set SDA */
	SCL = 1; /* Set SCL */
	I2C_delay();
	SDA = 0; /* Clear SDA */
	I2C_delay();
	SCL = 0; /* Clear SCL */
}

void I2C_stop(void)
{
	if(SCL)
	SCL = 0; /* Clear SCL */
	SDA = 0; /* Clear SDA */
	I2C_delay();
	SCL = 1; /* Set SCL */
	I2C_delay();
	SDA = 1; /* Set SDA */
}

bit I2C_write(unsigned char dat)
{
	bit data_bit;
	unsigned char i;
	for(i=0;i<8;i++) /* For loop 8 time(send data 1 byte) */
	{
		data_bit = dat & 0x80; /* Filter MSB bit keep to data_bit */
		SDA = data_bit; /* Send data_bit to SDA */
		I2C_clock();       /* Call for send data to i2c bus */
		dat = dat<<1;
	}
	SDA = 1; /* Set SDA */
	I2C_delay();
	SCL = 1; /* Set SCL */
	I2C_delay();
	data_bit = SDA;   /* Check acknowledge */
	SCL = 0; /* Clear SCL */
	I2C_delay();
	return data_bit; /* If send_bit = 0 i2c is valid */
}

unsigned char I2C_read(void)
{
	bit rd_bit;
	unsigned char i, dat;
	dat = 0x00;
	for(i=0;i<8;i++) /* For loop read data 1 byte */
	{
		I2C_delay();
		SCL = 1; /* Set SCL */
		I2C_delay();
		rd_bit = SDA; /* Keep for check acknowledge */
		dat = dat<<1;
		dat = dat | rd_bit; /* Keep bit data in dat */
		SCL = 0; /* Clear SCL */
	}
	return dat;
}

void I2C_ack()
{
	SDA = 0; /* Clear SDA */
	I2C_delay();
	I2C_clock(); /* Call for send data to i2c bus */
	SDA = 1; /* Set SDA */
}

void I2C_noack()
{
	SDA = 1; /* Set SDA */
	I2C_delay();
	I2C_clock(); /* Call for send data to i2c bus */
	SCL = 1; /* Set SCL */
}
#endif

 

/***************************
* File name: Seven_Seg_Symbols.h
* Has the numberic equivalents of
* possible 7 segement charecters
* Numbers in table: active high segments, (bit0,bit1..bit6,bit7) correspond to
* segments (a,b..g,h). Many fonts are defined as three horizontal bars to indicate
* that how to define them on 7-segment display is not known
***************************/

#ifndef _SEVEN_SEGEMENT_SYMBOLS_H
#define _SEVEN_SEGEMENT_SYMBOLS_H


//Numbers
#define NUMERIC_ZERO  0x3F
#define NUMERIC_ONE   0x06
#define NUMERIC_TWO   0x5B
#define NUMERIC_THREE 0x4F
#define NUMERIC_FOUR  0x66
#define NUMERIC_FIVE  0x6D
#define NUMERIC_SIX   0x7D
#define NUMERIC_SEVEN 0x07
#define NUMERIC_EIGHT 0x7F
#define NUMERIC_NINE  0x6F

//Aplhabets

//Capitals
//The value is left to 0x49 if not possible

#define CAPITAL_A 0x77
#define SMALL_a   0x5F
#define CAPITAL_B 0x49 //Not possible
#define SMALL_b   0x7C
#define CAPITAL_C 0x39
#define SMALL_c   0x58
#define CAPITAL_D 0x49 //Not possible
#define SMALL_d   0x5E
#define CAPITAL_E 0x79
#define SMALL_e   0x7B
#define CAPITAL_F 0x71
#define SMALL_f   0x71
#define CAPITAL_G 0x7D
#define SMALL_g   0x6F
#define CAPITAL_H 0x76
#define SMALL_h   0x74
#define CAPITAL_I 0x06
#define SMALL_i   0x04
#define CAPITAL_J 0x0E
#define SMALL_j   0x0E
#define CAPITAL_K 0x49 //Not possible
#define SMALL_k   0x49 //Not possible
#define CAPITAL_L 0x38
#define SMALL_l   0x06 
#define CAPITAL_M 0x49 //Not possible
#define SMALL_m   0x49 //Not possible 
#define CAPITAL_N 0x37
#define SMALL_n   0x54 
#define CAPITAL_O 0x3F
#define SMALL_o   0x5C 
#define CAPITAL_P 0x73
#define SMALL_p   0x73 
#define CAPITAL_Q 0x49 //Not possible
#define SMALL_q   0x67 
#define CAPITAL_R 0x49 //Not possible
#define SMALL_r   0x50 
#define CAPITAL_S 0x6D
#define SMALL_s   0x6D 
#define CAPITAL_T 0x49 //Not possible
#define SMALL_t   0x49 //Not possible
#define CAPITAL_U 0x3E
#define SMALL_u   0x1C
#define CAPITAL_V 0x49 //Not possible
#define SMALL_v   0x49 //Not possible
#define CAPITAL_W 0x49 //Not possible
#define SMALL_w   0x49 //Not possible
#define CAPITAL_X 0x49 //Not possible
#define SMALL_x   0x49 //Not possible
#define CAPITAL_Y 0x6E
#define SMALL_y   0x6E
#define CAPITAL_Z 0x5B
#define SMALL_z   0x5B

#define NUMERIC_NULL 0x49

unsigned char SevenSeg_DisplayNumber(unsigned char Value)
{
	switch(Value)
	{

		case 0x00:
		{
			return NUMERIC_ZERO;
		}

		case 0x01:
		{
			return NUMERIC_ONE;
		}

		case 0x02:
		{
			return NUMERIC_TWO;
		}

		case 0x03:
		{
			return NUMERIC_THREE;
		}

		case 0x04:
		{
			return NUMERIC_FOUR;
		}

		case 0x05:
		{
			return NUMERIC_FIVE;
		}

		case 0x06:
		{
			return NUMERIC_SIX;
		}

		case 0x07:
		{
			return NUMERIC_SEVEN;
		}

		case 0x08:
		{
			return NUMERIC_EIGHT;
		}

		case 0x09:
		{
			return NUMERIC_NINE;
		}
		
		default:
		{
			return NUMERIC_NULL;
		}
	}
}

#endif