Touch toggle light

The project involves creating a simple traffic light control mechanism using a touch sensor and a traffic light LED module. When the touch sensor is activated, the LEDs will cycle through the following sequence: Red -> Yellow -> Green.

1. Build the Circuit

• Arduino UNO R4 Minima Board

• Touch Sensor Module

• Traffic Light Module

2. Code

1. Open the 08-Touch_toggle_light.ino file under the path of ultimate-sensor-kit\fun_project\08-Touch_toggle_light, or copy this code into Arduino IDE.

3. Code explanation

This project operates on a simple principle: when a touch is detected on the touch sensor, the next LED in the sequence (Red -> Yellow -> Green) will light up. The state of which LED is currently active is managed by the variable currentLED.

1. Define pins and initial values

   const int touchSensorPin = 2;  // touch sensor pin
   const int rledPin = 9;         // red LED pin
   const int yledPin = 8;         // yellow LED pin
   const int gledPin = 7;         // green LED pin
   int lastTouchState;     // the previous state of touch sensor
   int currentTouchState;  // the current state of touch sensor
   int currentLED = 0;     // current LED 0->Red, 1->Yellow, 2->Green
   

   These lines define the pins that we connect the components to on the Arduino board and initialize the states for touch and LEDs.

2. setup() function

   void setup() {
     Serial.begin(9600);              // initialize serial
     pinMode(touchSensorPin, INPUT);  // configure touch sensor pin as input
     // set LED pins as outputs
     pinMode(rledPin, OUTPUT);
     pinMode(yledPin, OUTPUT);
     pinMode(gledPin, OUTPUT);
     currentTouchState = digitalRead(touchSensorPin);
   }
   

   This function runs once when the Arduino is powered on or reset. Here, the touch sensor is set as an input (it will read values), while the LEDs are set as outputs (we will set their values). Also, the serial communication is started to allow debugging, and the initial touch state is read.

3. loop() function

   void loop() {
     lastTouchState = currentTouchState;               // save the last state
     currentTouchState = digitalRead(touchSensorPin);  // read new state
     if (lastTouchState == LOW && currentTouchState == HIGH) {
       Serial.println("The sensor is touched");
       turnAllLEDsOff();  // Turn off all LEDs
       // switch on the next LED in sequence
       switch (currentLED) {
         case 0:
           digitalWrite(rledPin, HIGH);
           currentLED = 1;
           break;
         case 1:
           digitalWrite(yledPin, HIGH);
           currentLED = 2;
           break;
         case 2:
           digitalWrite(gledPin, HIGH);
           currentLED = 0;
           break;
       }
     }
   }
   

   In the main loop, the current touch state is read and compared with the previous one. If a touch is detected (transition from LOW to HIGH), all LEDs are turned off, and the next one in the sequence is turned on.

4. Turn off LEDs function

   void turnAllLEDsOff() {
     digitalWrite(rledPin, LOW);
     digitalWrite(yledPin, LOW);
     digitalWrite(gledPin, LOW);
   }
   

   This function, when called, will turn off all the LEDs by setting their pins to LOW.