{"id":82378,"date":"2025-01-15T08:13:51","date_gmt":"2025-01-15T13:13:51","guid":{"rendered":"https:\/\/www.engineersgarage.com\/?p=82378"},"modified":"2025-02-24T12:55:08","modified_gmt":"2025-02-24T17:55:08","slug":"arduino-based-traffic-light-system-for-four-way-crossroad","status":"publish","type":"post","link":"https:\/\/www.engineersgarage.com\/arduino-based-traffic-light-system-for-four-way-crossroad\/","title":{"rendered":"How to design an Arduino-based traffic light system"},"content":{"rendered":"

Traffic light systems are important signaling devices that regulate the flow of vehicles and pedestrians at intersections, crosswalks, and other critical areas. These systems use three primary lights \u2014 red, yellow (amber), and green \u2014 to manage traffic effectively and ensure safety<\/a>.<\/p>\n

In this project, we’ll create a traffic light system for a four-way intersection using an Arduino microcontroller, RGB LEDs<\/a>, and an MAX7219 IC-based 7-segment display board. This project aims to replicate real-world traffic light operations, providing a functional and educational model of a standard traffic control system.<\/p>\n

Components<\/h3>\n
    \n
  1. Arduino MEGA x1<\/li>\n
  2. 7-Segments x8<\/li>\n
  3. MAX7219 IC x1<\/li>\n
  4. RGB LEDs x4<\/li>\n
  5. Breadboard x1<\/li>\n
  6. Jumper or connecting wires<\/li>\n<\/ol>\n

    The traffic light system<\/strong><\/h3>\n

    In this project, we’ll design a traffic light system for a four-way intersection, with each direction labeled as A, B, C, and D. The system includes red, orange (amber), and green lights, along with a timer for each direction.<\/p>\n

    At any given time, the green light will activate for only one direction, allowing traffic to flow, while the other directions remain stopped with red lights. This setup effectively manages traffic flow, similar to real-world traffic control systems.<\/p>\n

    \"\"<\/a><\/p>\n

    At the four-way, vehicles in intersection A are allowed to proceed first, followed by those in B, then C, and finally D. By regulating traffic in this sequence, the traffic lights follow the pattern shown in the table below, ensuring a systematic flow of vehicles and minimizing congestion at each intersection.<\/p>\n

    \"\"<\/a><\/p>\n

    Note, that the traffic light pattern repeats itself starting from the fifth step. Assuming the green light remains active for 20 seconds for each intersection and the orange light stays on for five seconds, the traffic signal operates according to the time schedule shown below.<\/p>\n

    \"\"<\/a><\/p>\n

    Initially, the signal for intersection B remains red for 25 seconds, for C it stays red for 50 seconds, and for D it remains red for 75 seconds. After completing the first cycle of signals for each direction, the signal follows a consistent pattern: green for 20 seconds, orange for 5 seconds, and red for 75 seconds for each way.<\/p>\n

    With the assumption that the signal remains green for 20 seconds and orange for 5 seconds for each intersection, let’s design the full traffic light system.<\/p>\n

    Circuit connections<\/strong><\/h3>\n

    In this project, we’re using the MAX7219 IC-based 7-segment driver module to display the timer for each signal. The MAX7219 is an 8-digit common-cathode LED display driver that enables interfacing a microcontroller with 7-segment display units of up to 8 digits.<\/p>\n

    The four ways of the crossroad are mapped to the 7-segment displays on the module, as shown in the image below.<\/p>\n

    \"\"<\/a>In the module, the data pins of the 7-segment displays are connected to the SEG A to SEG G and DP pins of the MAX7219. The common-cathode terminals of the segments are linked to MAX7219’s DIG0 to DIG7 pins. The IC’s pins 4 and 9 are connected to the ground pin, while pin 19 is connected to the 5V terminal.<\/p>\n

    MAX7219’s pin 18 is also connected to 5V DC via an appropriate resistor. The DIN, LOAD, and CLK pins of the IC can be connected to Arduino’s\u00a0 digital I\/O pins.<\/p>\n

    The MAX7219 communicates with the Arduino using an SPI-compatible interface. Specifically, the DIN, LOAD, and CLK pins of the IC are connected to Arduino’s pins 12, 10, and 11, respectively. The MAX7219 module is powered with 5V DC and grounded through the Arduino itself.<\/p>\n

    The red, green, and orange signals are represented using RGB LEDs. The circuit connections for the RGB LEDs are outlined in the table below.<\/p>\n

    \"\"<\/a><\/p>\n

    The circuit diagram for the project is shown in the image below.<\/p>\n

    \"\"<\/p>\n

    The Arduino sketch<\/strong><\/h3>\n

    Before making the circuit connections, upload the following sketch to Arduino MEGA.<\/p>\n