Published June 10, 2017 © GPL3+

Color-changing Lamp Via Temperature Input

This project detects changes in temperature based on your specifications, and then changes the color of a LED to the color of your choosing.

BeginnerProtip8,614

Color-changing Lamp Via Temperature Input

Things used in this project

Hardware components

Arduino UNO

Jumper wires (generic)

Temperature Sensor

from kit

Resistor 221 ohm

red red brown

Adafruit Flora RGB Neopixel LEDs- Pack of 4

starter kit

Story

This project is a simple combination of Projects 3 and 4 from the starter kit. There is a note at the end of Project 4 asking us to think about different inputs to the color changing lamp's LED pins. I thought that lighting up different LED's in the Love-o-meter was pretty cool, but the same idea could be integrated into PWM for each pin with some "if" statements. If anyone has input on how to make the transition from color to color as the temperature rises more smooth, please comment! I would like to have this feature on possible future projects.

Anyways, I'm sure this project has been done before, but I thought it may be a good idea to practice sharing my projects as well.

In the main picture, use a shot glass with holes in it as the cover to the LED; they recommend a ping-pong ball with a hole in it to diffuse the light.

Enjoy!

Code

Temperature Incremental Changes

const int greenLEDPin = 9;    // LED connected to digital pin 9
const int redLEDPin = 10;     // LED connected to digital pin 10
const int blueLEDPin = 11;    // LED connected to digital pin 11

// room temperature in Celcius
const float baselineTemp = 20.0;

const float baselineSens = 144;
const int TempSensor = A0;  // pin with the temp sensor

int redValue = 0; // value to write to the red LED
int greenValue = 0; // value to write to the green LED
int blueValue = 0; // value to write to the blue LED

void setup() {
  // initialize serial communications at 9600 bps:
  Serial.begin(9600);

  // set the digital pins as outputs
  pinMode(greenLEDPin, OUTPUT);
  pinMode(redLEDPin, OUTPUT);
  pinMode(blueLEDPin, OUTPUT);
}

void loop() {

  // read the value on AnalogIn pin 0
  // and store it in a variable
  int sensorVal = analogRead(TempSensor);
  delay(5);
  //Serial.println(sensorVal);
   // convert the ADC reading to voltage
   // convert temp sensor reading from 0-1024 to analogWrite value from 0-255 
  float voltage = (sensorVal / 1024.0) * 5.0;
 
  
    // Send the voltage level out the Serial port
  Serial.print("Volts: ");
  Serial.print(voltage);
  
  // convert the voltage to temperature in degrees C
  // the sensor changes 10 mV per degree
  // the datasheet says there's a 500 mV offset
  // ((volatge - 500mV) times 100)
  Serial.print(", degrees C: ");
  float temperature = (voltage - .5) * 100;
  Serial.println(temperature);
  if (temperature < baselineTemp) {
  analogWrite(redLEDPin, 0);
  analogWrite(greenLEDPin, 127);
  analogWrite(blueLEDPin, 0);
  }else if (temperature >= baselineTemp && temperature < baselineTemp + 2) {
  analogWrite(redLEDPin, 0);
  analogWrite(greenLEDPin, 255);
  analogWrite(blueLEDPin, 0);
  } // if the temperature rises 2-4 degrees, turn an LED on
  else if (temperature >= baselineTemp + 2 && temperature < baselineTemp + 4) {
  analogWrite(redLEDPin, 0);
  analogWrite(greenLEDPin, 0);
  analogWrite(blueLEDPin, 255);
  } // if the temperature rises 4-6 degrees, turn a second LED on
  else if (temperature >= baselineTemp + 4 && temperature < baselineTemp + 6) {
  analogWrite(redLEDPin, 127);
  analogWrite(greenLEDPin, 0);
  analogWrite(blueLEDPin, 127);
  } // if the temperature rises more than 6 degrees, turn all LEDs on
  else if (temperature >= baselineTemp + 6) {
  analogWrite(redLEDPin, 255);
  analogWrite(greenLEDPin, 0);
  analogWrite(blueLEDPin, 0);
  }
  delay(1);


}