Traffic Light System Using Raspberry Pi 3 (Python)

Introduction

 

This article demonstrates how to make a smart traffic system using Raspberry Pi and Python.

 

Learn how to use the GPIO pins on your Raspberry Pi to interface with electronic components, such as LEDs, Buzzer and buttons.

 

 

Prerequisite 

 

Hardware 

 

As well as a Raspberry Pi with an SD card and the usual peripherals, you'll also  need:

• 1x Solderless breadboard
• All king of jumper leads 
• 1x Tactile button
• 3x LEDs (Red, Green, and Yellow)
• 3x 330 ohm Register
• Buzzer
• Button

Software

   

Raspberry Pi needs NOOBS OS. NOOBS is a way of making setting up a Raspberry Pi for the first time much, much easier. You won't need network access, and you won't need to download imaging software. Just head to the download page, grab a copy of the NOOBS zip file and unpack it onto a freshly formatted 4GB (or larger) SD card. Once you have installed an operating system, your Pi will boot as normal.

 

 

GPIO pins 

 

One powerful feature of the Raspberry Pi is the row of GPIO pins along the top edge of the board. GPIO stands for General-Purpose Input/Output. These pins are a physical interface between the Raspberry Pi and the outside world.

 

 

If you don't have a pin label, then this can help you to identify the pin numbers

 

 

3.3 volts           

    

Anything connected to these pins will always get 3.3 v of power.

 

5 volts 

   

Anything connected to these pins will always get 5 v of power.

 

GND

 

Zero volts, used to complete a circuit

 

GPIO

   

These pins are for general-purpose use and can be configures as input or output pins

 

ID_SC/ID_SD/DNC

 

Special purpose pins. 

 

Lighting an LED 

 

LEDs are delicate little things. if you put too much current through them they will pop. To limit the current going through the LED, you should always use a register in series with it.

 

Long leg an LED to the Pi 3.3v and the short leg to a GND pin. Automatically LED will turn ON

 

 

If you connect special purpose(GPIO) pin are connect to a long leg, make sure to write the import code.

 

 

Switching an LED on and off

 

GPIO Zero is a new Python library which provides a simple interface to everyday GPIO component. It comes installed by default in Rasbian.

 

Open IDLE(Integrated Development Environment), which you can use to write and run code.

 

Raspbian Menu Icon >> Programming >> Python 3 (IDLE). 

 

• To create a new file in IDLE, You can click on File and then New File in IDLE's menu bar. 
• Create a new file by clicking File >> New File

• Save the new file by clicking File >> Save. Save the file as trffic.py
• You'll need the LED Class, and to tell it that the LED is on pin 17. Write the following code in your new file.

from gpiozero import LED
led = LED(17)

• To make the LED switch on, type the following and press Enter

led.on()

• To make it switch off you can type 

led.off()

  Your LED should switch on and then off again. But that's not all you can do. Similarly checks the Buzzer and Button. Just import a Buzzer and Button for the header file.

 

Making Traffic Light

 

We need a breadboard, three LEDs, a button, a buzzer, and the necessary jumper cables and registers.

 

Wiring

 

First, you need to understand how each component is connected.

• A push-button requires 1 ground pin and 1 GPIO pin
• An LED requires 1 ground pin and 1 GPIO pin, with a current limiting register
  
• A buzzer requires 1 ground pin and 1 GPIO pin

Place the components on the breadboard and connect them to the Raspberry Pi GPIO pins, according to the following diagram.

 

 

Component GPIO pin 

 

   Button                           21

   Red LED                       25

   Yellow LED                    8

   Green LED                    7

   Buzzer                           15

 

This is the same as the Switching and LED on and off step

• Open Python 3 from the main menu
• Create a new file just save with the project name.py

Add TrafficLight, Button and Buzzer Code

from gpiozero import Button, TrafficLights, Buzzer
from time import sleep

buzzer = Buzzer(15)
button = Button(21)
lights = TrafficLights(25, 8, 7)

while True:
           button.wait_for_press()
           buzzer.on()
           light.green.on()
           sleep(1)
           lights.amber.on()
           sleep(1)
           lights.red.on()
           sleep(1)
           lights.off()
           buzzer.off()

OUTPUT

 

Run your Powershell coding (F5)

 

Finally, we have successfully created a smart traffic system using a Raspberry Pi.