Arduino Nano ESP32 - Traffic Light

In this tutorial, we will explore how to utilize the Arduino Nano ESP32 to control a traffic light module. In detail, we will learn:

Hardware Preparation

1×Arduino Nano ESP32
1×USB Cable Type-C
1×Traffic Light Module
1×Jumper Wires
1×(Recommended) Screw Terminal Adapter for Arduino Nano

Or you can buy the following sensor kit:

1×DIYables Sensor Kit 30 types, 69 units
Disclosure: Some of the links provided in this section are Amazon affiliate links. We may receive a commission for any purchases made through these links at no additional cost to you. We appreciate your support.

Overview of Traffic Light Module

Pinout

A traffic light module includes 4 pins:

  • GND pin: The ground pin, connect this pin to GND of Arduino Nano ESP32.
  • R pin: The pin to control the red light, connect this pin to a digital output of Arduino Nano ESP32.
  • Y pin: The pin to control the yellow light, connect this pin to a digital output of Arduino Nano ESP32.
  • G pin: The pin to control the green light, connect this pin to a digital output of Arduino Nano ESP32.
Traffic Light Pinout

How It Works

Wiring Diagram

The wiring diagram between Arduino Nano ESP32 and traffic light

This image is created using Fritzing. Click to enlarge image

How To Program For Traffic Light module

  • Configure an ESP32's pins to the digital output mode by using pinMode() function
pinMode(PIN_RED, OUTPUT); pinMode(PIN_YELLOW, OUTPUT); pinMode(PIN_GREEN, OUTPUT);
digitalWrite(PIN_RED, HIGH); // turn on RED digitalWrite(PIN_YELLOW, LOW); // digitalWrite(PIN_GREEN, LOW); delay(RED_TIME); // keep red led on during a period of time

Arduino Nano ESP32 Code

/* * This Arduino Nano ESP32 code was developed by newbiely.com * * This Arduino Nano ESP32 code is made available for public use without any restriction * * For comprehensive instructions and wiring diagrams, please visit: * https://newbiely.com/tutorials/arduino-nano-esp32/arduino-nano-esp32-traffic-light */ #define PIN_RED D3 // The Arduino Nano ESP32 pin connected to R pin of traffic light module #define PIN_YELLOW D4 // The Arduino Nano ESP32 pin connected to Y pin of traffic light module #define PIN_GREEN D5 // The Arduino Nano ESP32 pin connected to G pin of traffic light module #define RED_TIME 4000 // RED time in millisecond #define YELLOW_TIME 4000 // YELLOW time in millisecond #define GREEN_TIME 4000 // GREEN time in millisecond void setup() { pinMode(PIN_RED, OUTPUT); pinMode(PIN_YELLOW, OUTPUT); pinMode(PIN_GREEN, OUTPUT); } // The loop function repeats indefinitely void loop() { // red light on digitalWrite(PIN_RED, HIGH); // turn on digitalWrite(PIN_YELLOW, LOW); // turn off digitalWrite(PIN_GREEN, LOW); // turn off delay(RED_TIME); // keep red light on during a period of time // yellow light on digitalWrite(PIN_RED, LOW); // turn off digitalWrite(PIN_YELLOW, HIGH); // turn on digitalWrite(PIN_GREEN, LOW); // turn off delay(YELLOW_TIME); // keep yellow light on during a period of time // green light on digitalWrite(PIN_RED, LOW); // turn off digitalWrite(PIN_YELLOW, LOW); // turn off digitalWrite(PIN_GREEN, HIGH); // turn on delay(GREEN_TIME); // keep green light on during a period of time }

Detailed Instructions

To get started with Arduino Nano ESP32, follow these steps:

  • If you are new to Arduino Nano ESP32, refer to the tutorial on how to set up the environment for Arduino Nano ESP32 in the Arduino IDE.
  • Wire the components according to the provided diagram.
  • Connect the Arduino Nano ESP32 board to your computer using a USB cable.
  • Launch the Arduino IDE on your computer.
  • Select the Arduino Nano ESP32) board and its corresponding COM port.
  • Copy the above code and open with Arduino IDE
  • Click Upload button on Arduino IDE to upload code to Arduino Nano ESP32
  • Check out the traffic light module

It's important to note that the exact workings of a traffic light can vary depending on the specific design and technology used in different regions and intersections. The principles described above provide a general understanding of how traffic lights operate to manage traffic and enhance safety on the roads.

The code above demonstrates individual light control. Now, let's enhance the code for better optimization.

Arduino Nano ESP32 Code Optimization

  • Let's improve the code by implementing a function for light control.
/* * This Arduino Nano ESP32 code was developed by newbiely.com * * This Arduino Nano ESP32 code is made available for public use without any restriction * * For comprehensive instructions and wiring diagrams, please visit: * https://newbiely.com/tutorials/arduino-nano-esp32/arduino-nano-esp32-traffic-light */ #define PIN_RED D3 // The Arduino Nano ESP32 pin connected to R pin of traffic light module #define PIN_YELLOW D4 // The Arduino Nano ESP32 pin connected to Y pin of traffic light module #define PIN_GREEN D5 // The Arduino Nano ESP32 pin connected to G pin of traffic light module #define RED_TIME 2000 // RED time in millisecond #define YELLOW_TIME 1000 // YELLOW time in millisecond #define GREEN_TIME 2000 // GREEN time in millisecond #define RED 0 // Index in array #define YELLOW 1 // Index in array #define GREEN 2 // Index in array const int pins[] = { PIN_RED, PIN_YELLOW, PIN_GREEN }; const int times[] = { RED_TIME, YELLOW_TIME, GREEN_TIME }; void setup() { pinMode(PIN_RED, OUTPUT); pinMode(PIN_YELLOW, OUTPUT); pinMode(PIN_GREEN, OUTPUT); } // The loop function repeats indefinitely void loop() { // red light on trafic_light_on(RED); delay(times[RED]); // keep red light on during a period of time // yellow light on trafic_light_on(YELLOW); delay(times[YELLOW]); // keep yellow light on during a period of time // green light on trafic_light_on(GREEN); delay(times[GREEN]); // keep green light on during a period of time } void trafic_light_on(int light) { for (int i = RED; i <= GREEN; i++) { if (i == light) digitalWrite(pins[i], HIGH); // turn on else digitalWrite(pins[i], LOW); // turn off } }
  • Let's improve the code by using a for loop.
/* * This Arduino Nano ESP32 code was developed by newbiely.com * * This Arduino Nano ESP32 code is made available for public use without any restriction * * For comprehensive instructions and wiring diagrams, please visit: * https://newbiely.com/tutorials/arduino-nano-esp32/arduino-nano-esp32-traffic-light */ #define PIN_RED D3 // The Arduino Nano ESP32 pin connected to R pin of traffic light module #define PIN_YELLOW D4 // The Arduino Nano ESP32 pin connected to Y pin of traffic light module #define PIN_GREEN D5 // The Arduino Nano ESP32 pin connected to G pin of traffic light module #define RED_TIME 2000 // RED time in millisecond #define YELLOW_TIME 1000 // YELLOW time in millisecond #define GREEN_TIME 2000 // GREEN time in millisecond #define RED 0 // Index in array #define YELLOW 1 // Index in array #define GREEN 2 // Index in array const int pins[] = {PIN_RED, PIN_YELLOW, PIN_GREEN}; const int times[] = {RED_TIME, YELLOW_TIME, GREEN_TIME}; void setup() { pinMode(PIN_RED, OUTPUT); pinMode(PIN_YELLOW, OUTPUT); pinMode(PIN_GREEN, OUTPUT); } // The loop function repeats indefinitely void loop() { for (int light = RED; light <= GREEN; light ++) { trafic_light_on(light); delay(times[light]); // keep light on during a period of time } } void trafic_light_on(int light) { for (int i = RED; i <= GREEN; i ++) { if (i == light) digitalWrite(pins[i], HIGH); // turn on else digitalWrite(pins[i], LOW); // turn off } }
  • Let's improve the code by using millis() function intead of delay().
/* * This Arduino Nano ESP32 code was developed by newbiely.com * * This Arduino Nano ESP32 code is made available for public use without any restriction * * For comprehensive instructions and wiring diagrams, please visit: * https://newbiely.com/tutorials/arduino-nano-esp32/arduino-nano-esp32-traffic-light */ #define PIN_RED D3 // The Arduino Nano ESP32 pin connected to R pin of traffic light module #define PIN_YELLOW D4 // The Arduino Nano ESP32 pin connected to Y pin of traffic light module #define PIN_GREEN D5 // The Arduino Nano ESP32 pin connected to G pin of traffic light module #define RED_TIME 2000 // RED time in millisecond #define YELLOW_TIME 1000 // YELLOW time in millisecond #define GREEN_TIME 2000 // GREEN time in millisecond #define RED 0 // Index in array #define YELLOW 1 // Index in array #define GREEN 2 // Index in array const int pins[] = { PIN_RED, PIN_YELLOW, PIN_GREEN }; const int times[] = { RED_TIME, YELLOW_TIME, GREEN_TIME }; unsigned long last_time = 0; int light = RED; // start with RED light void setup() { pinMode(PIN_RED, OUTPUT); pinMode(PIN_YELLOW, OUTPUT); pinMode(PIN_GREEN, OUTPUT); trafic_light_on(light); last_time = millis(); } // The loop function repeats indefinitely void loop() { if ((millis() - last_time) > times[light]) { light++; if (light >= 3) light = RED; // new circle trafic_light_on(light); last_time = millis(); } // TO DO: your other code } void trafic_light_on(int light) { for (int i = RED; i <= GREEN; i++) { if (i == light) digitalWrite(pins[i], HIGH); // turn on else digitalWrite(pins[i], LOW); // turn off } }

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