Temperature Sensor. Positive + (to 5 volts.) Ground. To A0 To GND Signal. To 5v

Transcription

1 Temperature Sensor This system measures the change in temperature and converts it to a colorful thermometer using LEDs. The first time you run the sketch, you will use the serial monitor to find the lowest temperature in the room. This will be referred to as the basetemp. The temperature sensor will be inserted into three female wires in the hex socket using one of the 3-wire holes. You will then program the LEDs to come on consecutively as the temperature on the sensor increases. Warning! Look at the labels on the pins below and be sure to run the wires to the proper pins. Wiring them up the wrong way can cause the sensor to get very hot. Positive + (to 5 volts.) To A0 To GND Signal To 5v Ground 62

2 Materials needed to wire a photoresistor and piezo buzzer. Use one of the 3 wire socket holes. Odyssey Board Hex Socket Block 3 F/F Jumper wires Temperature Sensor 3 LEDs Round Socket Block 3 F/F Resistor wires 3 F/F Jumper wires Set up the Odyssey Board, dowels, and socket blocks. (Wire clip is optional.) Your blocks may use any horizontal or vertical dowel holes. They do not have to look exactly like the ones shown. 63

3 Be sure to look at how the temperature sensor is curved. The front is the flat side. To 5v To A0 1. Place 3 female jumper wires in the socket block. Be sure the signal wire is in the center position. To GND 2. Place the temperature sensor in the socket wires. Be very careful to check the orientation. 3. Connect the wire from the GND pin to ground the blue header pin. 4. Connect the wire from the center pin to the A0 yellow signal pin. 5. Connect the wire from the 5v pin to the red 5v header pin Insert 3 jumper wires with 3 resistor wires in the circle socket block Insert 3 LEDs wired to ground and pins D2, D3, and D4. Mount the temperature resistor assembly and the LED assembly to the Odyssey Board. 64

4 Fine tune the sketch to your environment to create a colorful thermometer: Upload and run the Color Thermometer sketch. Open the serial monitor in the Arduino IDE. Observe the lowest temperature value recorded in the serial monitor. Change the basetemp value in the sketch to match the lowest value observed in the serial monitor. Upload the new sketch. Gently pinch the temperature sensor between your thumb and finger and watch the data on the Serial Monitor. After several seconds, let go of the sensor and lightly blow on it. What happens on the Monitor? Open the serial monitor to observe the changes in temperature. As the temperature increases in two degree increments, each LED should progressively light. See if you can add a 4th LED and add the code to make it light up. Think about how you could map other environmental sensors to various outcomes (sound pitch, light brightness, blink rates, etc). 65

5 int temperaturepin = A0; //This is will read the center pin of the temperature sensor. float basetemp = 24.0; //This is the lowest temperature before LEDs will begin turning on. void setup() { Serial.begin(9600); //This sets up the serial port so that the temperature can be read. pinmode(2, OUTPUT); // These lines set pins 2-5 as output and starts them being off. pinmode(3, OUTPUT); pinmode(4, OUTPUT); digitalwrite(2, LOW); digitalwrite(3, LOW); void loop() { int sensorval = analogread(temperaturepin); //Stores the value being read by the center pin. float voltage = (sensorval / ) * 5.0; //Converts the signal to volts. Serial.println("Degrees C: "); float temperature = (voltage -.5) * 100; //Converts the voltage to degrees celsius. Serial.print(temperature); //Prints the temperature to the serial monitor. if (temperature < basetemp) { // if the current temperature is lower than the basetemp turn all the LEDs off digitalwrite(2, LOW); digitalwrite(3, LOW); Continue to next page for the rest of the sketch. 66

6 (Continued from previous page) // if the temperature is between basetemp and 2 degrees above the basetemp turn on the first LED on else if (temperature >= basetemp && temperature < basetemp + 2) { digitalwrite(2, HIGH); digitalwrite(3, LOW); // if the temperature is between 2 and 4 degrees above basetemp turn first two LEDs on else if (temperature >= basetemp + 2 && temperature < basetemp + 4) { digitalwrite(2, HIGH); digitalwrite(3, HIGH); // if the temperature is above degrees C above base temp turn all LEDs on else if (temperature >= basetemp + 4) { digitalwrite(2, HIGH); digitalwrite(3, HIGH); digitalwrite(4, HIGH); delay(100); //wait 100 ms before checking the temperature again 67