Freeze when trying to do I2C on 16F688

[robert campbell2]

Hello:

My program freezes when the first I2C_WRITE is encountered. The code is below, followed by the header file:

#include <16F688.h>
#include "C:\robspicc\archivalV1\archivalV1.h"

long int read_temp();
long int TP;

byte const DS_ADDR_WR = 0x90;
byte const DS_ADDR_RD = 0x91;
byte const DS_PTR_CFG = 0x01;
byte const DS_PTR_TEMP = 0x00;
byte const CFG_12BIT_ON = 0x60;
byte const CFG_10BIT_ON = 0x20;
byte const CFG_9BIT_ON = 0x00;
byte const CFG_10BIT_OFF = 0x21;
byte const CFG_9BIT_OFF = 0x01;

void main()
{
output_high(PWR); //Turns on temp sensor power
output_float(DS_CLK);
output_float(DS_DAT);
delay_ms(2000);

while(1){
output_high(LED); //LED For Debug
delay_ms(10);
output_low(LED);

TP = read_temp();
printf("%lu\r\n",TP);
delay_ms(2000);
}
}
long int read_temp()
{
int r1, r2;
// Start a single convert
I2C_START();
I2C_WRITE(DS_ADDR_WR); //Always Freezes here
/////////////////////////DEBUG
output_high(LED); //Used to indicate whether code reaches this point
delay_ms(500);
output_low(LED);
/////////////////////////DEBUG
I2C_WRITE(DS_PTR_CFG);
I2C_WRITE(CFG_9BIT_ON);
I2C_STOP();
delay_us(10);
I2C_START();
I2C_WRITE(DS_ADDR_WR);
I2C_WRITE(DS_PTR_CFG);
I2C_WRITE(CFG_9BIT_OFF);
I2C_STOP();
delay_us(10);
// Re-position pointer to temperature register..
I2C_START();
I2C_WRITE(DS_ADDR_WR);
I2C_WRITE(DS_PTR_TEMP);
I2C_STOP();
// Get the temperature
I2C_START();
I2C_WRITE(DS_ADDR_RD);
delay_us(10);
r1 = I2C_READ();
r2 = I2C_READ(0);
I2C_STOP();
return ((r1 << 8)+ r2);
}

And for the header file:

#use delay(clock=38400)
#fuses LP,NOWDT,NOBROWNOUT,NOMCLR,PUT,NOIESO,NOFCMEN
#use rs232(baud=300,BRGH1OK,parity=N,xmit=PIN_C2,rcv=PIN_A3,bits=8,INVERT)
#use i2c(Master, SDA=PIN_A1, SCL=PIN_A0, slow)

#define PWR PIN_C3
#define LED PIN_C4
#define DS_CLK PIN_A0
#define DS_DAT PIN_A1[/code]

[Kasper]

make sure you have pull up resistors on the SDA and SCL lines, or it will indeed lock ( own experience )
3.3K or something should be good

[robert campbell2]

I do in fact have the pullup resistors. Any other thoughts?

Thanx

[robert campbell]

Also, MPLAB sim hangs on the first I2c write command.

[robert campbell]

Also, MPLAB sim hangs on the first I2c write command.

[PCM programmer]

I wouldn't worry about MPLAB-SIM. There's no way that the
simulator knows that those pins are supposed to be used for
an i2c bus. How would it know ?

I think your problem is likely due to the comparator module
that is on Port A of the 16F688. It needs to be disabled
before Port A can be used for digital i/o. CCS has a
function that can do this. Example: