ADT7301

Rev. B | Page 13 of 16

The following software program shows how to program a

PIC16F873 to communicate with the ADT7301. The

PIC16F873 is configured as an SPI master with the Port A.1 pin

used as CS. Any microchip microcontroller can use this

program by simply exchanging the include file for the device

that is being used.

#include <16F873.h>

#device adc = 8

#use delay(clock = 4000000)

#fuses NOWDT,XT, PUT, NOPROTECT, BROWNOUT, LVP

#BIT CKP = 0x14.4

#define CS PIN_A1

void main(){

int MSByte,LSByte;

long int ADC_Temp_Code;

float TempVal,ADC_Temp_Code_dec;

setup_spi(spi_master);

//Pic is set up as master device.

CKP = 1;

//Idle state of clock is high.

do{

delay_ms(10);

//Allow time for conversions.

Output_low(CS);

//Pull CS low.

delay_us(10);

//CS to SCLK set-up time.

MSByte = SPI_Read(0);

//The first byte is clocked in.

LSByte = SPI_Read(0);

//The second byte is clocked in.

delay_us(10);

//SCLK to CS set-up time.

Output_High(CS);

//Bring CS high.

ADC_Temp_Code = make16(MSByte,LSByte);

//16 bit ADC code is stored ADC_Temp_Code.

ADC_Temp_Code_dec = (float)ADC_Temp_Code;

//Convert to float for division.

if ((0x2000 & ADC_Temp_Code) == 0x2000)

//Check sign bit for negative value.

{

TempVal = (ADC_Temp_Code_dec - 16384)/32;

//Conversion formula if negative temperature.

}

else

{

TempVal = (ADC_Temp_Code_dec/32);

//Conversion formula if positive temperature.

}

}while(True);

//Temperature value stored in TempVal.

}