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Smart Fourway Traffic Light System Built with Arduino UNO
A four-way traffic signal control system based on the Arduino UNO platform provides a flexible, low-cost option for embedded systems laboratories and small intersection management. The design combines infrared sensors, traffic light modules and an I2C LCD display to create a closed-loop platform for monitoring traffic conditions and coordinating signal changes. Its core hardware architecture, wiring specifications and control logic are outlined below.
Core system architecture and components
The control system uses the Arduino UNO as its central processing unit. Built around the ATmega328P microcontroller, the board coordinates sensor inputs and actuator outputs.
Infrared sensors, traffic light modules and a 16x2 I2C LCD screen are integrated to support traffic status monitoring and display. The resulting configuration functions as a closed-loop platform for detecting vehicle or object movement, switching signal states and presenting countdown or status information.
| Component | Function | Interface/protocol |
|---|---|---|
| Arduino UNO | Central controller | Digital/analog I/O |
| IR sensor | Object or motion detection | Digital signal |
| Traffic light module | Red/yellow/green status indication | Digital GPIO |
| I2C LCD 16x2 | Information and countdown display | I2C (A4/A5) |
Hardware interface and wiring standards
Accurate wiring is fundamental to reliable logic execution. Under the design specification, all components share a common ground (GND) to maintain consistent voltage levels, while the VCC terminals of the sensors and display are connected to the 5V power pin.
- Sensor interface: Infrared sensor signals are received through digital pins D2 and D3.
- Traffic light interface: Digital pins D8 through D13 provide independent control of two traffic light groups.
- Display interface: The 16x2 LCD connects through pins A4 (SDA) and A5 (SCL), using the I2C protocol for data transmission.
The pin allocation keeps sensor input, signal output and display communication on distinct functional paths, reducing the risk of conflicting control signals during operation.
Control logic and implementation approach
The Arduino program logic relies primarily on the setup() and loop() functions. The setup() function configures pin modes, including defining digital pins as outputs, and initializes the LCD screen.
The loop() function operates as the main cycle. It continuously polls the infrared sensors, updates traffic light switching logic based on detected traffic flow and sends current countdown or status information to the LCD in real time.
The design notes indicate that further interrupt handling or state-machine logic would be required to ensure smooth and rigorous traffic light transitions.
