I tried using the alert bit to control the led at first. It didn't work too well, and very unpredictably. I doubt it even was working through the alert bit at all. So, for now it's just a brute force led turning up when the temperature goes higher than the value stored in the T_high register.
Ex: Temperature Sensor from naureenm on Vimeo.
// ARDUINO CODE
#include "wire.h" // (where " "=angled brackets)
int led = 2;
int ptrTemp = 0b00000000; // TMP102 register pointers
int ptrConf = 0b00000001;
int ptrTLow = 0b00000010;
int ptrTHigh = 0b00000011;
int i2cAddr; // used to set address on the chip
void setup()
{
pinMode(led,OUTPUT);
Serial.begin(9600);
Wire.begin(); // join i2c bus (address optional for master)
i2cAddr = 0b1001001; // ADD0 pin connection selects one of four possible addresses
}
void loop()
{
// REQUESTING TEMPERATURES
/* TEMPERATURE REGISTER
*/
Wire.beginTransmission(i2cAddr); // select temperature register
Wire.send(ptrTemp); // (if only temperature is needed this can
Wire.endTransmission(); // be done once in setup() )
Wire.requestFrom(i2cAddr, 2); // request temperature
byte byte1 = Wire.receive();
byte byte2 = Wire.receive();
/* T_LOW REGISTER
*/
Wire.beginTransmission(i2cAddr); // select temperature register
Wire.send(ptrTLow);
Wire.send(24); // (if only temperature is needed this can
Wire.endTransmission(); // be done once in setup() )
Wire.requestFrom(i2cAddr, 2); // request temperature
byte lowbyte1 = Wire.receive();
byte lowbyte2 = Wire.receive();
/* T_High REGISTER
*/
Wire.beginTransmission(i2cAddr); // select temperature register
Wire.send(ptrTHigh);
Wire.send(28); // (if only temperature is needed this can
Wire.endTransmission(); // be done once in setup() )
Wire.requestFrom(i2cAddr, 2); // request temperature
byte hibyte1 = Wire.receive();
byte hibyte2 = Wire.receive();
// CALCULATING TEMPERATURES
int tempint = byte1 << 8; // shift first byte to high byte in an int
tempint = tempint | byte2; // or the second byte into the int
tempint = tempint >> 4; // right shift the int 4 bits per chip doc
float tempflt = float( tempint ) * .0625; // calculate actual temperature per chip doc
// Low_temp
int lowtempint = lowbyte1 << 8; // shift first byte to high byte in an int
lowtempint = lowtempint | lowbyte2; // or the second byte into the int
lowtempint = lowtempint >> 4; // right shift the int 4 bits per chip doc
float lowtempflt = float( lowtempint ) * .0625; // calculate actual temperature per chip doc
// Hi_temp
int hitempint = hibyte1 << 8; // shift first byte to high byte in an int
hitempint = hitempint | hibyte2; // or the second byte into the int
hitempint = hitempint >> 4; // right shift the int 4 bits per chip doc
float hitempflt = float( hitempint ) * .0625; // calculate actual temperature per chip doc
// PRINTING TEMPERATURES
Serial.print( "Temp: C = ");
Serial.print( int( tempflt ) );
int tempF = (tempflt * 9/5) + 32;
Serial.print( " F = ");
Serial.print( int( tempF ) );
Serial.print( " Low: C = ");
Serial.print( int( lowtempflt ) );
int lowF = (lowtempflt * 9/5) + 32;
Serial.print( " F = ");
Serial.print( int( lowF ) );
Serial.print( " Hi: C = ");
Serial.print( int( hitempflt ) );
int hiF = (hitempflt * 9/5) + 32;
Serial.print( " F = ");
Serial.println( int( hiF ) );
// LIGHTING UP THE LED IF TOO HOT
if ( tempflt > hitempflt )
digitalWrite(led,HIGH);
else
digitalWrite(led,LOW);
delay(500);
}
