Team Del Burger:

Josh Stidham

•

Bill Rui

•

Jonathan Tenney

Published November 18, 2020 © GPL3+

RGB LED Selector

Not sure what colored light best sets the mood? Use the RGB LED to test every color of the visible light spectrum!

BeginnerFull instructions provided15 minutes270

Things used in this project

Hardware components

Texas Instruments EK-TM4C123GXL TM4C Tiva LaunchPad

Adafruit Standard LCD - 16x2 White on Blue

Rotary potentiometer (generic)

Jumper wires (generic)

Resistor 220 ohm

SparkFun Breadboard Power Supply Stick 5V/3.3V

9V 1A Switching Wall Power Supply

USB-A to Micro-USB Cable

Breadboard (generic)

Tilt Switch, SPST

Software apps and online services

Texas Instruments Energia

Story

Purpose-

Red, green, blue, indigo, purple, pink. I could go on, but you get the idea, there are a lot of colors! Despite this, when we look at nearly every light bulb around us, all we see is white. This is because white is a combination of red, green, and blue. When we adjust the amount of each color, we can unlock a whole spectrum of new colors.

What if we could use this to change the color of a light source with the turn of a knob? Well now you can with the RGB LED! This project features three different potentiometers that, when adjusted, affect the intensity of their respective color. One knob is for red, one knob is for green, and one knob is for blue; it’s as simple as that!

This project is a life-saver for when you want to try out different colors of light in different settings. You can use this project for anything from testing possible lights on a gaming computer all the way to choosing the best color of Christmas lights. The possibilities are endless!

Background-

Our engineering team of young Rice University students was approached and asked to make a useful design. It was simple. The design needed to be able to shine a bright light across the whole visible spectrum. We were free to use whatever parts we needed for the design. Firstly, we were provided with a Ti Launchpad kit that we needed to use for the design. Secondly, we were asked to implement a tilt switch in the design. With these specifications, we created the RBG LED!

Build Instructions-

(1) Using 3 potentiometers, a breadboard, jumper wires, and the Ti Launchpad, create the following circuit according to the schematic below.

Note: At this point, you will have a functional RGB LED. The potentiometers correspond to their respective wire color. Our team decided adding an LCD panel that displays the color-code of the LED would be extremely useful.

(2) Add the LCD panel and the fourth potentiometer. Connect pin 1 and pin 5 of the LCD panel to ground. Connect the last potentiometer to ground.

(3) Connect LCD pin 4 to PA7, pin 6 to PA6, pin 11 to PA5, pin 12 to PA4, pin 13 to PA3, and pin 14 to PA2. Connect LCD pin 3 to the output pin of the potentiometer.

(4) Add the 5V power supply. Connect the negative terminal to ground and the positive terminal to an empty slot of the breadboard. Connect a wire to pin 4, a wire to the potentiometer, and a 220 ohm resistor to pin 15 from the 5V power supply.

(5) Add a tilt switch between pin 16 and ground. This is the final schematic!

Here are images of the RGB LED and a video of it in action!

1 / 2 • LaunchPad

Overall Picture

Demostration

Simple Version (without LCD and tilt switch)

Project by: Josh Stidham (jls32), Johnathan Tenney (jrt11), Bill Rui (qr2)

Team: Del Burger

Code

Code

#include <LiquidCrystal.h>

// define input pins
#define REDI A9  // PE_4
#define GREENI A8  // PE_5
#define BLUEI A10  // PB_4
// define output pins
#define REDO 30
#define GREENO 39
#define BLUEO 40

int sensorPins[] = {REDI, GREENI, BLUEI};  // input pins for the potentiometers
int ledPins[] = {REDO, GREENO, BLUEO};  // LED pins
int brightness[3];  // brightness of leds

//define LCD pins
const int rs = 10, en = 9, d4 = 8, d5 = 13, d6 = 12, d7 = 11;
LiquidCrystal lcd(rs, en, d4, d5, d6, d7);


void setup() 
{
  //for debugging
  Serial.begin(9600);
  lcd.begin(16, 2);
  //welcome message
  lcd.print("Welcome to RGB!");
  //test LEDs
  analogWrite(ledPins[0], 255);
  delay(500);
  analogWrite(ledPins[0], 0);
  analogWrite(ledPins[1], 255);
  delay(500);
  analogWrite(ledPins[1], 0);
  analogWrite(ledPins[2], 255);
  delay(500);
  analogWrite(ledPins[2], 0);
  delay(500);
}

void loop() 
{
  
   //read the value from the sensor:
  for(int i = 0; i < 3; i++)
  {
    int value = (int) map(analogRead(sensorPins[i]), 0, 4095, 0, 255);  // scale the input value from 0-4095 to 0-255

    //set brightness to 0 when value is too small to completely turn off LED
    if(value < 1)
    {
      brightness[i] = 0;
    }
    else
    {
      brightness[i] = value;
    }
    delay(10);
  }
  delay(30);
  lcd.setCursor(0, 0);
  String redString = String(brightness[0], HEX);
  String greenString = String(brightness[1], HEX);
  String blueString = String(brightness[2], HEX);
  //ensure all have length 2
  if(redString.length() == 1)
  {
    redString = "0" + redString;
  }
    if(greenString.length() == 1)
  {
    greenString = "0" + greenString;
  }
    if(blueString.length() == 1)
  {
    blueString = "0" + blueString;
  }
  //print hex code to lcd
  lcd.print("HEX CODE: "  + redString + greenString + blueString);
  
  
   //write values to LEDs
  for(int i = 0; i < 3; i++)
  {
    analogWrite(ledPins[i], brightness[i]);  // turn the led on at given brightness
  }
  
}

Credits

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RGB LED Selector