Temperature Measurement

Code

#define aref_voltage 3.3 // we tie 3.3V to ARef and measure it with a multimeter!

int tempSensor1 = A0; // Define the pin of the LM35 sensor

int tempSensor2 = A2; //define the pin of the tmp36

const int numReadings = 100; // number of samples for temp reading

int tempReadings[numReadings]; // the readings from the lm35

int index = 0; // the index of the current reading

long total = 0; // the running total

int averageTemp = 0; // the average temp over 100 sample

int Max1 = 0; //Temp max reading

int Min1 = 1023; //temp min reading

int Max2 = 0;

int Min2 = 1023;

int tempReadings2[numReadings]; // the readings from the tmp36

int index2 = 0; // the index of the current reading

long total2 = 0; // the running total

int averageTemp2 = 0; // the average

float temp1 = 0; //temp LM35 in celsius

float temp2 = 0; //temp TMP36 in celsius

float tempMax1 = 0; //Temp max LM35 in celsius

float tempMin1 = 0; //Temp min LM35 in celsius

float tempMax2 = 0; //Temp max TMP36 in celsius

float tempMin2 = 0; //temp min TMP36 in celsius

void setup() {

Serial.begin(9600); //init serial port for printing

// initialize all the readings to 0:

for (int thisReading = 0; thisReading < numReadings; thisReading++) {

tempReadings[thisReading] = 0;

tempReadings2[thisReading] = 0;

}

analogReference(EXTERNAL); //setup the ref voltage of the ADC to external

}

void loop() {

readingTemp1 (); //call the function to read sensor LM35

readingTemp2(); //call the function to read sensor TMP36

// Print result on serial port

Serial.print("Sensor1:");

Serial.print (temp1);

Serial.print("Max=");

Serial.print(tempMax1);

Serial.print("Min=");

Serial.println(tempMin1);

Serial.print("Sensor2:");

Serial.print (temp2);

Serial.print("Max=");

Serial.print(tempMax2);

Serial.print("Min=");

Serial.println(tempMin2);

}

int readingTemp1 () {

// subtract the last reading:

total = total - tempReadings[index];

// read from the sensor:

tempReadings[index] = analogRead(tempSensor1);

// add the reading to the total:

total = total + tempReadings[index];

// advance to the next position in the array:

index = index + 1;

// if we're at the end of the array...

if (index >= numReadings)

// ...wrap around to the beginning:

index = 0;

// calculate the average:

averageTemp = total / numReadings;

//record the temp max

if (averageTemp > Max1) {

Max1 = averageTemp;

}

//record the temp min

if (averageTemp < Min1 && averageTemp < Max1) {

Min1 = averageTemp;

}

// temp calculation in celsius for LM35

temp1 = ((averageTemp * aref_voltage) / 1024) * 100 ;

tempMax1 = ((Max1 * aref_voltage) / 1024) * 100;

tempMin1 = ((Min1 * aref_voltage) / 1024) * 100;

delay(10);

return temp1;

return tempMax1;

return tempMin1;

}

int readingTemp2 () {

// subtract the last reading:

total2 = total2 - tempReadings2[index2];

// read from the sensor:

tempReadings2[index2] = analogRead(tempSensor2);

// add the reading to the total:

total2 = total2 + tempReadings2[index2];

// advance to the next position in the array:

index2 = index2 + 1;

// if we're at the end of the array...

if (index2 >= numReadings)

// ...wrap around to the beginning:

index2 = 0;

// calculate the average:

averageTemp2 = total2 / numReadings;

//record temp max

if (averageTemp2 > Max2) {

Max2 = averageTemp2;

}

//record temp min

if (averageTemp2 < Min2 && averageTemp2 < Max2) {

Min2 = averageTemp2;

}

//temp calculation for TMP36

temp2 = (((averageTemp2 * aref_voltage) / 1024) - 0.5) * 100 ;

tempMax2 = (((Max2 * aref_voltage) / 1024) - 0.5) * 100;

tempMin2 = (((Min2 * aref_voltage) / 1024) - 0.5) * 100;

delay(10);

return temp2;

return tempMax2;

return tempMin2;

}