SDA line low

[crcn22]

Hello,
I'm using a PIC18F6722 in I2C master mode and PIC16F2520, TCN35, DS1339 and a EEPROM(24FC512) in a slave mode.
The problem is that to the end of some time, the program of the PIC18F6722 crash, and reset always by watchdog of minute to minute. When I'm going to see the line of SDA, this is low all the time. Why??? What can provoke this?

Code for 18F6722

#include <18F6722.h>
#fuses EC_IO, NOBROWNOUT, WDT16384, NOPUT, NOSTVREN, NODEBUG, PROTECT, PUT, LVP
#use delay(clock=20000000)
#use rs232(baud=9600, parity=N, xmit=PIN_C6, rcv=PIN_C7, bits=8, errors, stream=USART_A)
#use rs232(baud=9600, parity=N, xmit=PIN_G1, rcv=PIN_G2, bits=8, errors, stream=USART_B)
#use rs232(baud=19200, parity=N, xmit=PIN_C0, rcv=PIN_B1, bits=8, stream=USART_C)
#use i2c(Master, SLOW, sda=PIN_C4, scl=PIN_C3)

//some functions of read and write in I2C

//for 18F2520
void Read_GPS(unsigned int8 CMD)
{
char reg_gps[PIC_GPS_LENTGH_REG];
unsigned int8 i;
boolean GPS_OK,flag=true;

do {
delay_ms(PIC_GPS_TIME_WRITE);//5ms
i2c_start();
i2c_write(PIC_GPS_ADDRESS | PIC_GPS_WRITE);
delay_ms(PIC_GPS_START_TIME_WRITE);
i2c_write(CMD);
delay_ms(PIC_GPS_TIME_WRITE);
i2c_start();
i2c_write(PIC_GPS_ADDRESS | PIC_GPS_READ);
delay_ms(PIC_GPS_TIME_WRITE);
switch (CMD)
{
case READ_PIC_GPS_ALR:
for (i=0;i<PIC_GPS_LENTGH_ALR-1;i++)
{
reg_gps[CMD+i]=i2c_read(1);
delay_ms(PIC_GPS_TIME_READ);
}
reg_gps[CMD+i]=i2c_read(0);
i2c_stop();
Processar_Alarmes(reg_gps);
GPS_OK=true;
break;
case READ_PIC_GPS_LOC:
for (i=0;i<PIC_GPS_LENTGH_LOC-1;i++)
{
reg_gps[CMD+i]=i2c_read(1);
delay_ms(PIC_GPS_TIME_READ);
}
reg_gps[CMD+i]=i2c_read(0);
i2c_stop();
GPS_OK=Processar_Localizacao(reg_gps);
break;
case READ_PIC_GPS_VER_FW:
for (i=0;i<PIC_GPS_LENTGH_VER_FW_REV_ID-1;i++)
{
reg_gps[CMD+i]=i2c_read(1);
delay_ms(PIC_GPS_TIME_READ);
}
reg_gps[CMD+i]=i2c_read(0);
i2c_stop();
GPS_OK=Processar_Versoes(reg_gps);
break;
}
}

//for 16F2520
void Write_GPS(unsigned int8 CMD, char STR[], unsigned int8 LENGTH)
{
unsigned int8 i;

delay_ms(PIC_GPS_TIME_WRITE);
i2c_start();
i2c_write(PIC_GPS_ADDRESS | PIC_GPS_WRITE);
delay_ms(PIC_GPS_START_TIME_WRITE);
i2c_write(CMD);
for (i=0;i<LENGTH>> 16);
i2c_start();
i2c_write(EEXC51X | (chip<<1>> 8));
i2c_write((int8)(ADRESS & 0x000000FF));
i2c_write(DADO);
i2c_stop();
output_high(DEC_CS0);
delay_ms(5);
}

//for 24FC512
unsigned int8 read_24xc51x(unsigned int32 ADRESS)
{
unsigned int8 chip,DADO;

#ifdef __24XC515
if (bit_test(ADRESS,15))
bit_set(ADRESS,18);
else
bit_clear(ADRESS,18);
#endif
chip=(int8)(ADRESS >> 16);
i2c_start();
i2c_write(EEXC51X | (chip<<1>> 8));
i2c_write((int8)(ADRESS & 0x000000FF));
i2c_start();
i2c_write(EEXC51X | (chip<<1) | EEREAD);
DADO=i2c_read(0);
i2c_stop();
delay_us(5);
return DADO;
}

//forDS1339
void write_rtc(unsigned int8 REGISTO, unsigned int8 VALOR)
{
i2c_start();
i2c_write(ADR_RTC | RTC_WRITE);
i2c_write(REGISTO);
i2c_write(VALOR);
i2c_stop();
}

//forDS1339
unsigned int8 read_rtc(unsigned int8 REGISTO, boolean MODO)
{
unsigned int8 time=0;

delay_us(4);
i2c_start();
i2c_write(ADR_RTC | RTC_WRITE);
i2c_write(REGISTO);
i2c_start();
i2c_write(ADR_RTC | RTC_READ);
time=i2c_read(0);
i2c_stop();
return time;
}


//for TCN75
int16 th_read(byte ADDR_CHIP)
{
int8 th1=0;
int8 th2=0;
int16 th=0;

i2c_start();
i2c_write((TCN75_ADDR | ADDR_CHIP | TCN75_WRITE));
i2c_write(TCN75_TEMP);
i2c_start();
i2c_write((TCN75_ADDR | ADDR_CHIP | TCN75_READ));
th1=i2c_read(1);
th2=i2c_read(0);
i2c_stop();
if (bit_test(th1,7))
{
th1=th1-1;
th1=~th1;
bit_set(th1,7);
}
th=th1;
th=((th<<8) | th2);
return th;
}

//For TCN75
void th_escreve_config(byte ADDR_CHIP, byte CONFIG)
{
i2c_start();
i2c_write((TCN75_ADDR | ADDR_CHIP | TCN75_WRITE));
i2c_write(TCN75_PRCONF);
i2c_write(CONFIG);
i2c_stop();
}




Note: I need to put delays between all the i2c functions(i2c_start, i2c_read, i2c_write and i2c_stop)??

Thanks[/list]

[PCM programmer]