Double Transducer: Light Color to Rotation

An electronic setup placed on a chipboard. On the left side, a breadboard holds a light color sensor. On the right side, another breadboard is topped with three small LED lights in red, green, and blue. A second sensor is positioned next to the lights to measure brightness. A small servo motor is included in the assembly, which rotates based on the sensor’s readings.

Project picture

Detail photos

A APDS-9960 color sensor is on breadboard and connected to arduino uno behind it by jumpers

Color sensor APDS-9960 on breadboard

One LED light on

A LCD screen is mounted on chipboard connected to Arduino through a small yellow breadboard. The LCD displays the input and output data

LCD connected to Arduino

Three lighting up LED with different color are connected on a breadboard

All three lED lights on

Final project movies

IMG_5512.mov

Narrative description

On the left side of the chipboard, there is a small white board with a light color sensor attached to it, positioned so that it faces toward the opposite side. On the right side, there is another white board, and mounted on top of it are three lights, each emitting a different color. When the color sensor detects a specific light, a corresponding number of lights on the right board will turn on. It could be one, two, or all three. Next to these lights, a second sensor is placed to measure the overall intensity of the illumination. The reading from this intensity sensor controls the servo motor, with its values mapped to determine the rotation angle.

Progress images

Each image with caption and alt text.

skip button conntected through breadboard

Middle step LED lights connected through breadboard

Middle step Photoresistor connected through breadboard

Discussion

It has been a great experience to engage in these hands-on works and actually build something tangible. Looking back on my design and building process, I feel that I did a good job understanding the interaction sequence of the system, and the coding side went relatively smoothly. I was able to translate my design intentions into functioning code.

That said, I also see areas where I could improve. My understanding of the electronic components still feels a bit shallow. For instance, in this project I used a light color sensor as the input, but I processed the data simply by averaging the RGB values without realizing at the time that this essentially gave me brightness rather than meaningful color differentiation. Similarly, with the LCD display, I didn't notice the need to use the clear function, so the digits overflowed and cluttered the screen.

I think these issues could have been avoided if I had started the project earlier and given myself more time to carefully test and refine the input and output behaviors. Being more mindful of the details of the electronic components.

Functional block diagram and electrical schematic

Code

#include <Adafruit_APDS9960.h>

/***************************************************************************

Double Transducer: light color to rotation

This script uses the Adafruit library to read RGB value of light, then calculates the

average of RGB value and uses it to determine the number of LEDs turned on. More

LEDs get turned on means the reading of photoresistor will be higher. The reading of

photoresistor determines the angle of rotation. When the skip button is pressed, the script

will directly map the average of RGB value to the rotation angle of the servo motor.

Pin mapping table:

component Arduino pin role

servo motor 7 output

skip button 8 input

blue LED 11 output

yellow LED 12 output

green LED 13 output

photoresistor A3 input

credit:

intial ideation with G Meloche

***************************************************************************/

#include <Servo.h>

#include "Adafruit_APDS9960.h"

#include <Wire.h>

#include <LiquidCrystal_I2C.h>

LiquidCrystal_I2C lcd(0x27,20,2);

Adafruit_APDS9960 apds;

const int MOTORPIN = 7;

const int PHOTOPIN = A3;

const int BUTTONPIN = 8;

const int BLUELED = 11;

const int YELLOWLED = 12;

const int GREENLED = 13;

Servo ServoMotor;

void setup() {

pinMode(BUTTONPIN,INPUT);

pinMode(PHOTOPIN,INPUT);

pinMode(BLUELED, OUTPUT);

pinMode(YELLOWLED, OUTPUT);

pinMode(GREENLED, OUTPUT);

ServoMotor.attach(MOTORPIN);

Serial.begin(115200);

if(!apds.begin()){

Serial.println("failed to initialize device! Please check your wiring.");

}

else Serial.println("Device initialized!");

//enable color sensign mode

apds.enableColor(true);

//Display setup

lcd.init();

lcd.backlight();

lcd.setCursor(0,0);

lcd.print("i:");

lcd.setCursor(6,0);

lcd.print("m:");

lcd.setCursor(12,1);

lcd.print("o:");

}

void loop() {

//create some variables to store the color data in

uint16_t r, g, b, c;

int button = digitalRead(BUTTONPIN);

int photoVal = analogRead(PHOTOPIN);

//wait for color data to be ready

while(!apds.colorDataReady()){

delay(5);

}

//get the data and print the different channels

apds.getColorData(&r, &g, &b, &c);

Serial.print("photoVal: ");

Serial.print(photoVal);

Serial.print("red: ");

Serial.print(r);

Serial.print(" green: ");

Serial.print(g);

Serial.print(" blue: ");

Serial.print(b);

Serial.print(" clear: ");

Serial.println(c);

Serial.println();

int avg = (r+g+b)/3;

Serial.print("avg:");

Serial.println(avg);

//lcd input print

lcd.setCursor(2,0);

int inputLCD = map(avg, 0,100,0,99);

lcd.print(inputLCD);

Serial.print("LCD input:");

Serial.println(inputLCD);

lcd.noDisplay();

delay(100);

lcd.display();

delay(100);

int degree = map(avg, 0,80,10,170);

if (button==1){

//if button is pressed

digitalWrite(BLUELED,LOW);

digitalWrite(YELLOWLED,LOW);

digitalWrite(GREENLED,LOW);

ServoMotor.write(degree);

}

else{

if (avg>10){

digitalWrite(BLUELED,HIGH);

digitalWrite(YELLOWLED,LOW);

digitalWrite(GREENLED,LOW);

lcd.setCursor(8,0);

lcd.print("1 on");

}

if (avg>15){

digitalWrite(YELLOWLED,HIGH);

digitalWrite(BLUELED,HIGH);

digitalWrite(GREENLED,LOW);

lcd.setCursor(8,0);

lcd.print("2 on");

}

if (avg>20){

digitalWrite(GREENLED,HIGH);

digitalWrite(YELLOWLED,HIGH);

digitalWrite(BLUELED,HIGH);

lcd.setCursor(8,0);

lcd.print("3 on");

}

lcd.setCursor(8,1);

int lcdMSensor = map(photoVal, 650, 850, 0, 99);

Serial.print("lcdphotoVal:");

Serial.println(lcdMSensor);

lcd.print(lcdMSensor);

degree = map(photoVal, 700, 850, 10, 170);

ServoMotor.write(degree);

Serial.print("degree:");

Serial.println(degree);

//lcd.setCursor(14,1);

//int lcdOut = map(degree, 10 , 170, 0, 99);

//lcd.print(lcdOut);

}

lcd.setCursor(14,1);

int lcdOut = map(degree, 10 , 170, 0, 99);

lcd.print(lcdOut);

//delay(100);

}

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