Traffic Light System Simulation

Learn how to build and simulate a complete traffic light control system using STM32F401 microcontroller and Proteus

Introduction

Traffic lights are essential components of modern urban infrastructure that regulate vehicular flow at intersections by assigning right-of-way to specific directions. This project demonstrates how to simulate a basic traffic light system using the STM32F401RETx microcontroller and Proteus software.

The goal is to validate the control logic and hardware configuration in a virtual environment before physical deployment, ensuring cost-effective and error-free testing.

Hardware and Software Requirements

Hardware

  • 📦 STM32F401RETx microcontroller
  • 💡 Six LEDs (for simulation in Proteus)
  • 🔌 Resistors (330Ω) for each LED

Software

  • 💻 STM32CubeIDE for code development and configuration
  • 🔧 Proteus Professional 8 for circuit design and simulation

Development Process

  • STM32CubeIDE Configuration

    Configure the microcontroller's clock speed, memory, and GPIO pins for traffic light control.

    Traffic Light System Flowchart

  • Program Development

    Develop the C program in main.c to cycle through traffic light states (red, yellow, green) using HAL library functions.

    void update_traffic_light( GPIO_PinState Red1, GPIO_PinState Yellow1, GPIO_PinState Green1, GPIO_PinState Red2, GPIO_PinState Yellow2, GPIO_PinState Green2, uint32_t delay ) { HAL_GPIO_WritePin(GPIOA, GPIO_PIN_0, Red1); HAL_GPIO_WritePin(GPIOA, GPIO_PIN_1, Yellow1); HAL_GPIO_WritePin(GPIOA, GPIO_PIN_2, Green1); HAL_GPIO_WritePin(GPIOB, GPIO_PIN_3, Red2); HAL_GPIO_WritePin(GPIOB, GPIO_PIN_4, Yellow2); HAL_GPIO_WritePin(GPIOB, GPIO_PIN_5, Green2); HAL_Delay(delay); }

  • Building and Downloading

    Compile the program into a HEX file for Proteus simulation using STM32CubeIDE's build function.

  • Proteus Schematic Design

    Design a schematic with the STM32F401RE microcontroller and virtual LEDs in Proteus.

    Traffic Light System Flowchart

  • Importing HEX File

    Load the compiled HEX file into the Proteus microcontroller model.

  • Simulation

    Run the simulation to verify that virtual LEDs illuminate according to the programmed sequence.

Implementation Details

GPIO Pin Configuration

  • PA0 → Red Light (Intersection 1)
  • PA1 → Yellow Light (Intersection 1)
  • PA2 → Green Light (Intersection 1)
  • PB3 → Red Light (Intersection 2)
  • PB4 → Yellow Light (Intersection 2)
  • PB5 → Green Light (Intersection 2)

Traffic Light Sequence

while (1) { // Phase 1: Red1 ON, Green2 ON update_traffic_light( GPIO_PIN_SET, GPIO_PIN_RESET, GPIO_PIN_RESET, GPIO_PIN_RESET, GPIO_PIN_RESET, GPIO_PIN_SET, 5000 ); // Phase 2: Yellow1 ON update_traffic_light( GPIO_PIN_RESET, GPIO_PIN_SET, GPIO_PIN_RESET, GPIO_PIN_RESET, GPIO_PIN_RESET, GPIO_PIN_SET, 2000 ); // Phase 3: Green1 ON, Red2 ON update_traffic_light( GPIO_PIN_RESET, GPIO_PIN_RESET, GPIO_PIN_SET, GPIO_PIN_SET, GPIO_PIN_RESET, GPIO_PIN_RESET, 5000 ); // Phase 4: Yellow2 ON update_traffic_light( GPIO_PIN_RESET, GPIO_PIN_RESET, GPIO_PIN_SET, GPIO_PIN_RESET, GPIO_PIN_SET, GPIO_PIN_RESET, 2000 ); }

Results and Conclusion

The project successfully simulated a traffic light system using STM32CubeIDE and Proteus. The virtual LEDs illuminated according to the programmed sequence, confirming that the control logic worked as expected.

Key achievements:

  • ✅ Successfully configured STM32F401RETx microcontroller for traffic light control
  • ✅ Developed optimized code using function-based approach to reduce redundancy
  • ✅ Verified functionality through Proteus simulation before physical implementation
  • ✅ Demonstrated effective hardware-software integration for embedded systems

Future Enhancements

This project can be extended with additional features, such as:

  • 🚦 Integration of real-time traffic data for adaptive timing
  • 🚶 Addition of pedestrian crossing signals
  • 🚑 Implementation of emergency vehicle detection and priority
  • 📡 Wireless communication for coordinating multiple intersections
  • 📊 Data logging and traffic pattern analysis capabilities