I2C bus causes reset

[Tomson]

Hello,

I'd like to program a i2c bus between a pic and a DAC. The pic I'am using is a PIC18F2480 with hardware i2c. The DAC is a MAX5812L with the device adress 0x20.

My code is running until the first i2c_write() instruction. It seems to me, that the watchdog causes a reset of the pic after I´ve called this function.

My PCWH compiler version is 4.023.

Can anybody explain this error to me?

Here´s my code...

// ************************************************************************
//
// I2C testprogram
//
// date: 09-May-2007
//
// software information:
//
// compiler: PCWH
// version: V4.023
// IDE: MPLAB V7.50
//
// hardware information:
//
// master: PIC18F2480 use of hardware I2C
//
// slave: MAX5812L write adress: 0x20
// read adress: 0x21
//
// I2C bus: pull up resistors in scl and sda (4k7)
//
// ************************************************************************

// Header Dateien
#include "18f2480.h"

#define STATUS_LED1 PIN_C1
#define STATUS_LED2 PIN_C2

// I2C...
#define Cmd_PowerUp 0x40
#define Cmd_PowerDown0 0x44
#define Cmd_PowerDown1 0x48
#define Cmd_PowerDown2 0x4C
#define SLAVE_WRITE_ADRESS 0x20
#define SLAVE_READ_ADRESS 0x21

// Configuration Bytes
//#fuses H4,WDT128,PROTECT, BROWNOUT, BORV20, NOLVP, NODEBUG
#fuses H4, PROTECT
#fuses BROWNOUT
#fuses WDT128, BORV42
#fuses PUT, NOCPD, STVREN, NODEBUG
#fuses NOLVP, NOWRT, NOWRTD, NOIESO, FCMEN
#fuses NOPBADEN, BBSIZ1K, NOWRTC, NOWRTB, NOEBTR
#fuses NOEBTRB, CPB, NOLPT1OSC, MCLR
#fuses NOXINST


#use delay(clock=40000000)
#use fast_io(A)
#use fast_io(B)
#use fast_io(C)
#use I2C(Master, sda=PIN_C4, scl=PIN_C3, FORCE_HW, STREAM=DAC)


#zero_ram

void main(void)
{
// lokals...
int i8_temp1, i8_outputhigh, i8_outputlow;


// set up´s
SETUP_ADC_PORTS(ALL_ANALOG);
SETUP_ADC(ADC_CLOCK_DIV_16);
SET_TRIS_A(0b11111111);
SET_TRIS_B(0b11001000);
SET_TRIS_C(0b00000000);
SETUP_TIMER_0(RTCC_8_BIT | RTCC_DIV_32 );
SETUP_WDT(WDT_ON);

// switch off the status led´s
OUTPUT_BIT(STATUS_LED1, 0);
OUTPUT_BIT(STATUS_LED2, 0);
delay_ms(20);


// main loop
do {

OUTPUT_BIT(STATUS_LED1, 1);
delay_ms(20);

// Power up slave device MAX5812L
I2C_START(DAC);
I2C_WRITE(SLAVE_WRITE_ADRESS); // device adress SLAVE_WRITE_ADRESS = 0x20
I2C_WRITE(Cmd_PowerUp); // device command Cmd_PowerUp = 0x40
I2C_STOP(DAC);

OUTPUT_BIT(STATUS_LED2, 1);
delay_ms(20);

i8_outputhigh = 0xFF;
i8_outputlow = 0xFF;

// output dac value...(12Bit)
i8_temp1 = i8_outputhigh & 0x0F;
i8_temp1 = 0xC0 | i8_temp1;

I2C_START(DAC);
I2C_WRITE(SLAVE_WRITE_ADRESS); // device adress SLAVE_WRITE_ADRESS = 0x20
I2C_WRITE(i8_temp1); // device command 0xC..+ 12 Bit data
I2C_WRITE(i8_outputlow);
I2C_STOP(DAC);


// Power down slave device MAX5812L
I2C_START(DAC);
I2C_WRITE(SLAVE_WRITE_ADRESS); // device adress SLAVE_WRITE_ADRESS = 0x20
I2C_WRITE(Cmd_PowerDown0); // device command Cmd_PowerDown0 = 0x44
I2C_STOP(DAC);

// switch off the status led´s
OUTPUT_BIT(STATUS_LED1, 0);
OUTPUT_BIT(STATUS_LED2, 0);
delay_ms(20);


restart_wdt(); // restart watchdog timer


} while (TRUE);


}

Thank you.

Tomson[/code]

[PCM programmer]

[Tomson]

Hello PCM Programmer,

thanks for your fast reply. Obviously the problem is solved. But I have to change the #use i2c instruction too.

The following code (snipped) does work well.


#use I2C(Master, sda=PIN_C4, scl=PIN_C3, STREAM=DAC)

SET_TRIS_C(0b00011000);

Thanks again.

Best regards

Tomson