Project 6.04 High Temperature Alarm
We don’t do anything in this project that we haven’t done before, but we take a different approach. Here, we shift a lot of the work into functions. This makes the code easier to follow and easier to adapt for a new project. You can simply copy the functions and paste them into different projects.
Upload the program, wait a moment, and then open the serial monitor. The temperature will be output to the serial monitor in °C. When the temperature goes above the value of the float variable tooHot (set to 32.2 °C (90 °F)), the piezo sounds an alarm. You can breathe gently on the sensor to raise its temperature and trigger the alarm.
Concepts: I2C communication, wire library
Circuits:
Upload the program, wait a moment, and then open the serial monitor. The temperature will be output to the serial monitor in °C. When the temperature goes above the value of the float variable tooHot (set to 32.2 °C (90 °F)), the piezo sounds an alarm. You can breathe gently on the sensor to raise its temperature and trigger the alarm.
Concepts: I2C communication, wire library
Circuits:
Both the setup() and loop() blocks are simple in this program. Besides setting pinMode for the piezo and initializing the Serial object, the loop() block makes a call to the setupSensor function to set the sensor’s resolution and direct the pointer to register 1 (this code is explained in detail in Project 6.03):
void setupSensor(){
Wire.begin();
Wire.beginTransmission(address);
Wire.write(0x01);
Wire.write(0x60);
Wire.endTransmission();
Wire.beginTransmission(address);
Wire.write( byte(0x00)),
Wire.endTransmission();
}
The loop() block contains only three lines. The first starts the output line to the serial monitor:
Serial.print("TEMP = ");
The next line makes a call to our function getTemp and prints the result to the serial monitor with one decimal place. This all happens in one line:
Serial.println(getTemp(),1);
The third line makes another call to getTemp and calls the piezoTone function if the returned values is greater than 32.2:
if(getTemp() > 32.2) piezoTone(4000,10);
The getTemp function contains the code to read the temperature sensor and return a float value. The code is explained in Project 6.03:
float getTemp(){
Wire.requestFrom(address, byte(2));
tempreg = Wire.read();
tempreg= tempreg << 8;
tempreg |= Wire.read();
tempreg = tempreg >> 4;
temperature =( float ) tempreg / 16;
return temperature;ke
}
We used the piezoTone function in a lot of our other projects. This is a good example of portable code. We only needed to paste it into this sketch to use it for our alarm.
void setupSensor(){
Wire.begin();
Wire.beginTransmission(address);
Wire.write(0x01);
Wire.write(0x60);
Wire.endTransmission();
Wire.beginTransmission(address);
Wire.write( byte(0x00)),
Wire.endTransmission();
}
The loop() block contains only three lines. The first starts the output line to the serial monitor:
Serial.print("TEMP = ");
The next line makes a call to our function getTemp and prints the result to the serial monitor with one decimal place. This all happens in one line:
Serial.println(getTemp(),1);
The third line makes another call to getTemp and calls the piezoTone function if the returned values is greater than 32.2:
if(getTemp() > 32.2) piezoTone(4000,10);
The getTemp function contains the code to read the temperature sensor and return a float value. The code is explained in Project 6.03:
float getTemp(){
Wire.requestFrom(address, byte(2));
tempreg = Wire.read();
tempreg= tempreg << 8;
tempreg |= Wire.read();
tempreg = tempreg >> 4;
temperature =( float ) tempreg / 16;
return temperature;ke
}
We used the piezoTone function in a lot of our other projects. This is a good example of portable code. We only needed to paste it into this sketch to use it for our alarm.
