Hi,

I have a 18F452 running @20Mhz with a 20MHz crystal;
a HD44780 LCD in 4 bit mode connected to PORTD and PORTE
a LED connected to PORTB.7

I have also a DS1307 connected through I2C to the 18F452 with 10k
pullups at 100khz

what I am seeing..

- without ds1307 functions are not called, I don't get a Square Wave
output from the DS1307 -- fine.
- when ds1307_init() is called, I do get a Square Wave output from the
DS1307 -- fine.

- when ds1307_read() is called, the LED is lit up completely
indicating that MSSP is waiting for the Buffer to be full (BF)
indefinitely.
Now, If I don't look for that BF(Buffer Full) flag, all what I get
from the ds1307_read() is 0xff


Any Ideas, as to what could possibly be wrong in my code ?

Thanks,
Manu



#include <p18f452.h>
#include <stdio.h>
#include <i2c.h>
#include "delay.h"
#include "LCD.h"


#pragma config OSC =3D HS
#pragma config PWRT =3D ON
#pragma config WDT =3D OFF
#pragma config LVP =3D OFF


#define LED_PIN         PORTBbits.RB7

void ds1307_write(unsigned char reg, unsigned char data)
{
        unsigned char stat;


        IdleI2C(); /* wait for an idle bus */
        StartI2C(); /* send START bit */
        while (SSPCON2bits.SEN); /* wait till START is sent */
        WriteI2C(0xd0); /* DS1307 I2C address */
        AckI2C(); /* Slave ACK */
        WriteI2C(reg); /* Slave register address */
        AckI2C();
        WriteI2C(data); /* data */
        AckI2C();
        StopI2C();
        while (SSPCON2bits.PEN); /* wait till STOP is sent */
}

void ds1307_read(unsigned char reg, unsigned char *data)
{
        unsigned char i;


        IdleI2C();
        StartI2C();
        while (SSPCON2.bits.SEN);
        WriteI2C(0xd0);
        AckI2C();
        WriteI2C(0x00);
        AckI2C();


        StartI2C();
        while (SSPCON2bits.SEN);
        WriteI2C(0xd1);
        AckI2C();

        while (!SSPSTATbits.BF) {
                LED_PIN =3D 0;
        }
        LED_PIN =3D 1

        *data =3D ReadI2C();
        StopI2C();
        while (SSPCON2bits.PEN);
}

#define DS1307_CTL_OUT        (1 << 7)
#define DS1307_CTL_SQWE    (1 << 4)

#define DS1307_1Hz                (DS1307_CTL_OUT | DS1307_CTL_SQWE)

void ds1307_init(void)
{
        ds1307_write(0x00, 0x00); /* enable oscillator*/
        ds1307_write(0x07, DS1307_1Hz);
}


void main(void)
{
        TRISB =3D 0x00;
        TRISD =3D 0x00;
        TRISE =3D 0x00;
        ADCON1 =3D 0x0f;
        LED_PIN =3D 1; /* LED off */

        lcd_init();
        send_cmd(0x0c); /* turn OFF cursor */

        OpenI2C(MASTER, SLEW_OFF); /* I2C Master */
        SSPADD =3D 49; /* 100khz @ 20MHz */

        ds1307_init();

        set_cursor(1, 1); /* set cursor to R:1 C:1 */
        printf("-- DS1307 --");

        set_cursor(2, 1);
        while(1) {
                ds1307_read(0x00, &val);
                printf("S:%d ", val);
                LED_PIN =3D ~LED_PIN; /* blink LED */
                delay250ms();
        }
}
--=20
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