Traffic Light Simulator

🚦 Project 1: Traffic Light Simulator

1. Title

2. How It Works

This project emulates a standard traffic light sequence using three colored LEDs (Red, Yellow, Green). The ESP32 controls the LEDs in a repeating cycle:

Green for 5 seconds → vehicles go
Yellow for 2 seconds → warning to stop
Red for 5 seconds → vehicles stop
The timing is managed using non-blocking or blocking delays (blocking used here for simplicity), creating an automatic, continuous loop.

3. Hardware Required

All components are built into your trainer kit—no external wiring needed:

ESP32 DevKit (main controller)
LED1 (Green) – from CN7
LED2 (Yellow) – from CN7
LED3 (Red) – from CN7

✅ Confirmed from schematic: CN7 = 4 digital output LEDs connected to GPIO 16, 17, 18, 19.

4. Block Diagram / Pin Connection Table

5. Source Code (main.c)

// main.c - Traffic Light Simulator for ESP32 Trainer Kit

// Uses onboard LEDs: LED1=Green, LED2=Yellow, LED3=Red

#define GREEN_PIN 16

#define YELLOW_PIN 17

#define RED_PIN 18

void setup() {

// Configure LED pins as outputs

pinMode(GREEN_PIN, OUTPUT);

pinMode(YELLOW_PIN, OUTPUT);

pinMode(RED_PIN, OUTPUT);

// Ensure all LEDs start OFF

digitalWrite(GREEN_PIN, LOW);

digitalWrite(YELLOW_PIN, LOW);

digitalWrite(RED_PIN, LOW);

}

void loop() {

// Green ON → Go

digitalWrite(GREEN_PIN, HIGH);

digitalWrite(YELLOW_PIN, LOW);

digitalWrite(RED_PIN, LOW);

delay(5000); // 5 seconds

// Yellow ON → Prepare to stop

digitalWrite(GREEN_PIN, LOW);

digitalWrite(YELLOW_PIN, HIGH);

digitalWrite(RED_PIN, LOW);

delay(2000); // 2 seconds

// Red ON → Stop

digitalWrite(GREEN_PIN, LOW);

digitalWrite(YELLOW_PIN, LOW);

digitalWrite(RED_PIN, HIGH);

delay(5000); // 5 seconds

}

6. How the Project Works (Runtime Behavior)

On power-up or reset, the ESP32 initializes GPIO 16–18 as outputs.
All LEDs are turned OFF initially.
The program enters an infinite loop:
- Turns Green LED ON for 5 seconds → simulates "GO"
- Switches to Yellow LED for 2 seconds → "CAUTION"
- Switches to Red LED for 5 seconds → "STOP"
The cycle repeats automatically with no user input required.
Transitions are instantaneous (no fade or overlap).

7. Expected Output

Green LED lights steadily for 5 seconds, then turns off.
Yellow LED lights for 2 seconds, then turns off.
Red LED lights for 5 seconds, then turns off.
Sequence repeats indefinitely: Green → Yellow → Red → Green → …
No display, sound, or serial output — visual feedback only via onboard LEDs.

✅ Why It’s Effective:

Correct Pin Mapping:
Based on your schematic (Skematik Trainer Kit IoT ESP32.pdf), CN7 connects:
- LED1 → GPIO 16
- LED2 → GPIO 17
- LED3 → GPIO 18
  → Your #define values match exactly.
Clear State Logic:
Only one LED is ON at a time — no ambiguity or overlap.
Realistic Timing:
- Green: 5s (standard for go)
- Yellow: 2s (adequate warning)
- Red: 5s (allows cross-traffic or pedestrian phase)
Safe Initialization:
All LEDs start OFF to avoid unexpected states on boot.
Simple & Readable:
Easy for students to understand — ideal for educational use.

🔍 Verification from Your Schematic:

CN7 section shows 4 LEDs labeled LED1–LED4.
Connected to ESP32 DevKit pins D16, D17, D18, D19 (as per CN2 header mapping).
Each has a 330Ω resistor → safe for direct GPIO drive.

💡 Recommendation

You can enhance engagement by asking students to:

Modify timings (e.g., longer green for “main road”)
Add a pedestrian button (using CN6 SW1) to extend red
Simulate amber flash at night

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