ArduinoThermoSensor.ino

// Reads temperature from TMP36 sensor (from SparkFun electronics) on Arduino Pro Mini 3.3V 8MHz
// Reports the readings to serial port
// Plug Vcc of sensor to digital 12
// Plug Gnd of sensor to gnd of the board
// Plug Vout of sensor to analog 0
// Monitoring diode (digital 13) blinks while sensor is being read
const int power = 12;
const int monitor = 13;
const int analog = A0;
const int serialRate = 9600 * 4;

void setup() {
  // Beware: This is for Arduino Pro Mini 8MHz
  // most boards do not need this division
  Serial.begin(serialRate / 2);
  pinMode(power, OUTPUT);
}

void loop() {
  // Power up the thermo sensor
  digitalWrite(power, HIGH);
  // Power up monitor led
  digitalWrite(monitor, HIGH);
  // Wait for consistent ADC reading
  delay(150);
  // Read sensor value
  int value = analogRead(analog);
  digitalWrite(power, LOW);
  digitalWrite(monitor, LOW);

  // Print values to serial
  // Formula is 10mV per degree celsius for this sensor
  // Arduino reference is 3.3 on this board
  // ADC range is 0 to 1023 (10 bits)
  Serial.println(100 * value * (3.3 / 1023));
  // Flush serial to get more consistent decoding at the other end of serial link
  Serial.flush();
  
  // Wait for next loop
  delay(2000);
}

ProcessingSerialDecoder.pde

// Processing script (http://processing.org) to read thermal reports on serial port
// from Arduino code above. Displays temps as a visual thermometer. Fast, and ugly...

import processing.serial.*;

Serial port;

void setup() {
  size(120, 600);
  port = new Serial(this, "/dev/tty.usbserial-A601EQIH", 9600*4);
}

void draw() {
  if (port.available() > 0) {
    String input = port.readString();
    if (input != null) {
      if (input.length() == 7) {
        float temperature = float(input.substring(0, 6));
        println(temperature+"oC");
        
        if (temperature > 30.0) {
          temperature = 30.0;
        }
        if (temperature < 10.0) {
          temperature = 10.0;
        }
        float hauteur = (temperature - 10) * 600 / 20;
        
        line(21.0, "21°C");
        line(19.0, "19°C");
        line(23.0, "23°C");
        
        fill(255, 255, 255);
        rect(120 / 2 - 15, 10, 30, 590, 15, 15, 0, 0);
        fill(255, 0, 0);
        rect(120 / 2 - 15, 600 - hauteur, 30, hauteur, 15, 15, 0, 0);
      }
    }
  }
}

void line(float reference, String texte) {
  float hauteur = (reference - 10) * 600 / 20;
  line(120 / 2 + 15, 600 - hauteur, 120 / 2 + 30, 600 - hauteur);
  fill(0, 0, 0);
  text(texte, 120 / 2 + 25, 600 - hauteur - 10);
}