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friends,
I am trying to interface DS1307 RTC with pic16f887 controller via i2c.. while simulation i got the time and date.. but the problem is I have to write this time to my LCD… in this program I am trying to write the "hour" value to LCD..
but nothing visible in LCD… please help me..please checkout the attachment and MPLABx code too…
PIC clock= 20Mhz
I²C clock= 100Khz
DS1307 address= 1101000
I AM NOT SURE THAT THE CODES I WRITTEN INSIDE FUNCTION –>ds1307_read() is right or wrong…please help
Actually in code I am trying to display the value of "hour" in LCD.. using functions bcd2lowerch and bcd2upperch
when I tried to debug my code in proteus::—>>>
1). when I debugged the function call-> hour=ds1307_read(0x02), inside the function, returning value of x is equal to 2. which means the address-> 0x02 which is passing as the parameter in function hour=ds1307_read(0x02), is stored inside SSPBUF and returning as such… which means a right read from the hour register of ds1307, is not taking place…
2).Similarly, when I debugged the function call-> minutes = ds1307_read(0x01);inside the function, returning value of x is equal to 1. which means the address-> 0x01 which is passing as the parameter in function minutes = ds1307_read(0x01), is stored inside SSPBUF and returning as such… which means a right read from the minute register of ds1307, is not taking place…
3).Similarly, when I debugged the function call-> seconds = ds1307_read(0x00);inside the function, returning value of x is equal to 0. which means the address-> 0x00 which is passing as the parameter in function seconds = ds1307_read(0x00), is stored inside SSPBUF and returning as such… which means a right read from the second register of ds1307, is not taking place…please checkout the 2 attached images
________________________MPLAB CODE______________________________________
#include <stdio.h>
#include <stdlib.h>
#include<htc.h>
#define _XTAL_FREQ 20000000 //20Mhz
#define RS RC5
#define RW RC6
#define E RC7
__CONFIG(FOSC_HS & WDTE_OFF & PWRTE_ON & MCLRE_OFF & CP_OFF & CPD_OFF & BOREN_ON & IESO_ON & FCMEN_ON & LVP_OFF);
__CONFIG(BOR4V_BOR40V & WRT_OFF);
void init_i2c(void);
void ds1307_init(void);
void ds1307_write(unsigned char ,unsigned char);
unsigned short ds1307_read(unsigned short);
void wait_mssp(void);
void init_lcd();
void set_command(unsigned char);
void set_data(unsigned char *);
unsigned short seconds,minutes,hour;
unsigned short x;
unsigned char hourVal[5]={0};
unsigned char hourVal1[5]={0};
unsigned short a;
unsigned short b;
unsigned char bcd2upperch(unsigned char bcd);
unsigned char bcd2lowerch(unsigned char bcd);
void main(){
PORTD =0x00;
TRISD =0x00;
TRISC5 =0;
TRISC6 =0;
TRISC7 = 0;
init_lcd();
__delay_ms(100);
init_i2c();
__delay_ms(100);
while(1){
seconds = ds1307_read(0x00);
minutes = ds1307_read(0x01);
hour = ds1307_read(0x02);
a = bcd2lowerch(hour);
b = bcd2upperch(hour);
sprintf(hourVal,"hour=%d",b); //sprintf used to get output as string
sprintf(hourVal1,"%d",a);
set_command(0x80); //force cursor to begin in 1st line of LCD
set_data(hourVal);
set_data(hourVal1);
__delay_ms(1000);
}
}
unsigned char bcd2upperch(unsigned char bcd)
{
return((bcd >> 4) + '0');
}
unsigned char bcd2lowerch(unsigned char bcd)
{
return((bcd & 0x0f) + '0');
}
void init_i2c(void){
SSPSTAT=0x00;
SSPCON=0x00;
SSPCON2=0x00;
SSPADD=0x00;
PORTC=0x00;
TRISC3 =1;
TRISC4 =1;
SSPCON = 0b00101000;//0x28 i2c master mode
SSPADD = 0x31;//decimal–49.//value for SSPADD found using eqn–> clock =Fosc/ 4*(SSPADD +1); clock–100Khz, Fosc =20Mhz
SSPSTAT = 0b10000000; //0x80
TRISC3 =1;
TRISC4 =1;
ds1307_write(0,0×00);
}
unsigned short ds1307_read(unsigned short addr){
RCEN =1;
wait_mssp();
SSPBUF =0b11010000; //slave address(address of ds1307) + write bit;
wait_mssp();
SSPBUF =addr;
wait_mssp();
RSEN =1;
SSPBUF =0b11010001; //slave address(address of ds1307) + read bit;
wait_mssp();
ACKDT=1;
ACKEN =1;
PEN=1;
wait_mssp();
x = SSPBUF;
return x;
}
void ds1307_write(unsigned char addr ,unsigned char data){
SEN =1; //Start bit
wait_mssp();
SSPBUF = 0b11010000; //slave address(address of ds1307) + write bit
wait_mssp();
SSPBUF =addr;
wait_mssp();
SSPBUF = data;
wait_mssp();
PEN =1; //stop bit
wait_mssp();
}
void wait_mssp(void){
while(!SSPIF);
SSPIF =0;
}
void init_lcd(){
set_command(0x01); //display clear
set_command(0x38); //Function set — 8bit data and 2lines
set_command(0x0C); //display ON cursor ON BLINK off
set_command(0x06); //Increment cursor–shift display to RIGHT
set_command(0x0E); //DISPLAY ON CURSOR BLINK
set_command(0x80); //force cursor to begin in 1st line
}
void set_command(unsigned char command){
RS = 0; //command
RW = 0; //write
PORTD=command;
E =1;
__delay_ms(100);
E =0;
}
void set_data(unsigned char *a){
RS = 1; //data
RW =0; // write
while(*a)
{
PORTD = *a;
E =1;
__delay_ms(100);
E =0;
a++;
}
}
you need to follow this sequence as given in the datasheet –
Send Start condition
Transmit address to slave as a write command
Check for ACK from slave
Send data pointer address
Check for ACK from slave
Send Repeated Start condition
Transmit address to slave as a read command
Check for ACK from slave
Set receive enable on PIC
Generate ACK after byte is received
(repeat the previous 2 steps for every byte you want to receive)
Send Stop condition
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