No temperature output on RS232

[black_nickle]

Hi,
I am using PICDEM2 PLUS Demo Board. I used the codes (see below) to program my PIC18F4525 to read the temperature. It is working when i used a 4MHz crystal oscillator, however, when i changed my crystal to 20MHz and changed this to #use delay(clock=20000000), there's no output on my hyperterminal, can anyone guide me on this?..

Thank you.



#include <18F4525.H>
#fuses XT, NOWDT, PROTECT, BROWNOUT, PUT, NOLVP
#use delay(clock=20000000)
#use rs232(baud=9600, xmit=PIN_C6, rcv=PIN_C7, ERRORS)
#use i2c(master, sda=PIN_C4, scl=PIN_C3)

#define TC74_I2C_WRITE_ADDRESS 0x9A
#define TC74_I2C_READ_ADDRESS 0x9B
#define TC74_READ_TEMP_COMMAND 0x00
#define TC74_READ_CONFIG_COMMAND 0x01


signed int8 TC74_read_temperature(void);

//====================================
void main()
{
signed int8 temp;

while(1)
{
temp = TC74_read_temperature();
printf("Temperature (C) = %d\n\r", temp);
delay_ms(1000);
}

}

//====================================

// Read the temperature (in degrees Centigrade)
// from the TC74.

signed int8 TC74_read_temperature(void)
{
signed int8 retval;

i2c_start();
i2c_write(TC74_I2C_WRITE_ADDRESS);
i2c_write(TC74_READ_TEMP_COMMAND);

i2c_start(); // Re-start
i2c_write(TC74_I2C_READ_ADDRESS);
retval = i2c_read(0);
i2c_stop();

return(retval);
}

[Ttelmah]

You need to use the HS fuse for crystals above about 4MHz, or the oscillator won't work.
May be the whole problem.

Best Wishes

[black_nickle]

Oh yes!... my mistake.. !

Thanks for your help!!..........