Digital IO With Arduino Boards

Albert Hodo. Tangible User Interface. Fall 2022

Prompt: Design a good diffuser for your RGB LEDs (e.g. ping pong ball, Styrofoam, etc); Then connect 3 leds to an arduino and use Pulse Width Modulation to fake analog behaviour. Use the serial monitor to control the RGB values with multiple key presses. For example, pressing ‘r’ 5 times will set the brightness to 50% (or brightness = 127) and pressing ‘r’ 10 times will set it to 100% (or brightness = 255).

Components Used

1. Post-it notes (Paper)
2. plastic frosted countainer
3. 3 LEDs
4. 3 Resisters
5. 1 Breadboard
6. 1 Arduino Uno
7. Jump wires

Process: I created the first diffuser out of post-it notes inspired by the Japanese art of Origami. I followed the tutorial which can be found on YouTube here: https://www.youtube.com/watch?v=pFTfj2hkpts. I tested this with the arduino setup and realised the light wasnt bright enough because the paper was more opaque than I anticipated after the folding process. I then decided to use a frosted plastic as the diffuser. One way to allow the paper gain its translucent material is to soak it in oil which i didn't have access to, given the time constraint.

Concerning the Arduino Setup, i connected the wires to the resisters and the LEDs and made the code automate the fading process using the PWM. After which i used the Serial Monitor to send data to the code to change the values of the LEDs manually.

Code

char serInString[100];  // array that will hold the different bytes of the string. 100=100characters;
                        // -> you must state how long the array will be else it won't work properly
char colorCode;
float colorVal;
int count=0;
int redPin   = 11;   // Red LED,   connected to digital pin 9
int greenPin = 9;  // Green LED, connected to digital pin 10
int bluePin  = 10;  // Blue LED,  connected to digital pin 11
void setup() {
  pinMode(redPin,   OUTPUT);   // sets the pins as output
  pinMode(greenPin, OUTPUT);   
  pinMode(bluePin,  OUTPUT);
  Serial.begin(9600);
  analogWrite(redPin,   127);   // set them all to mid brightness
  analogWrite(greenPin, 127);   // set them all to mid brightness
  analogWrite(bluePin,  127);   // set them all to mid brightness
  Serial.println("enter color command (e.g. 'r43') :");  
}
void loop () {
//  count=0;
  // clear the string
  memset(serInString, 0, 100);
  //read the serial port and create a string out of what you read
  readSerialString(serInString);
    
  colorCode = serInString[0];
  if( colorCode == 'r' || colorCode == 'g' || colorCode == 'b' ) {
    int tempVal=countNumberOf(colorCode);
    Serial.print("temp debug 1: tempVal is: ");
    Serial.println(tempVal);
    if(tempVal<=10){
        colorVal=tempVal*25.5;
      }else{
        colorVal=255;
      }
    
    Serial.print("value is:");
    Serial.println(colorVal);
    if(colorCode == 'r') 
      analogWrite(redPin, colorVal);
    else if(colorCode == 'g')
      analogWrite(greenPin, colorVal);
    else if(colorCode == 'b')
      analogWrite(bluePin, colorVal);
      
   colorVal=0;
   tempVal=0;   //...not really needed   
  }
    
 
  
  delay(1000);  // wait a bit, for serial data
}
//read a string from the serial and store it in an array
//you must supply the array variable
void readSerialString (char *strArray) {
  int i = 0;
  if(!Serial.available()) {
    return;
  }
  while (Serial.available()) {
    strArray[i] = Serial.read();
    i++;
  }
}
int countNumberOf(char item){
  int tempCounter=0;
  for(int i=0; i<100;i++){
      if(serInString[i]==item){
//        tempCounter++;
        count++;
        Serial.print("the temp counter is: ");
        Serial.println(count);
        return count;
      }
      
    }
  }

Demo