Python and IoT: Working with Raspberry Pi

Introduction
Prerequisites
Setup
Step 1: Installing Python
Step 2: Setting up Raspberry Pi
Step 3: Interacting with GPIO
Step 4: Controlling GPIO with Python
Conclusion

Introduction

The Internet of Things (IoT) is the concept of connecting everyday objects to the internet, allowing them to send and receive data. Raspberry Pi, a small and affordable computer, can be used as an IoT device for various applications. In this tutorial, we will learn how to work with Python and Raspberry Pi to build IoT applications using the General-Purpose Input/Output (GPIO) pins. By the end of this tutorial, you will be able to control external devices connected to the GPIO pins of a Raspberry Pi using Python programming.

Prerequisites

Before starting this tutorial, you should have basic knowledge of Python programming language. Familiarity with Raspberry Pi hardware and setup would also be helpful but not mandatory.

Setup

To follow along with this tutorial, you will need the following:

A Raspberry Pi board (any version will work)
An SD Card (8GB or more) with Raspbian OS (or any other compatible OS) flashed onto it
Power supply for Raspberry Pi
Keyboard, mouse, and HDMI cable for initial setup
External devices (LEDs, buttons, sensors, etc.) to connect with the GPIO pins
Jumper wires to connect the GPIO pins with external devices

Step 1: Installing Python

Before we start working with the Raspberry Pi, let’s make sure we have Python installed. Raspberry Pi comes with Python pre-installed, but it’s always a good idea to update it to the latest version. Follow these steps to update Python:

Open the terminal on your Raspberry Pi.
Type the following command and press Enter to update the package lists:
```
sudo apt update
```
After the update, install Python by running the following command:
```
sudo apt install python3
```
Verify the installation by checking the Python version:
```
python3 --version
```
This should display the installed Python version, such as Python 3.7.3.

Step 2: Setting up Raspberry Pi

Once we have Python set up, we need to prepare the Raspberry Pi to interact with external devices. Follow these steps to set up the Raspberry Pi:

Power off the Raspberry Pi and disconnect it from power.
Connect the external devices (LEDs, buttons, sensors, etc.) to the GPIO pins of the Raspberry Pi. Refer to the documentation or pinout diagram of your Raspberry Pi model to identify the GPIO pins.
Reconnect the power supply to the Raspberry Pi.

Step 3: Interacting with GPIO

GPIO pins on the Raspberry Pi allow us to control and interact with external devices. GPIO stands for General-Purpose Input/Output and provides a way to read input signals from sensors or control output signals to devices.

Before we dive into coding, let’s understand the basic concepts of GPIO:

GPIO Pin Numbering: Raspberry Pi uses different numbering schemes for the GPIO pins. The two most commonly used numbering schemes are BCM (Broadcom SOC channel numbering) and Physical (the physical pin numbers on the Pi’s header). In this tutorial, we will use the BCM numbering scheme.
GPIO Direction: GPIO pins can be set as input or output. Input pins read signals from external devices, while output pins control devices connected to them.
GPIO State: GPIO pins can be in two states: high or low. High signifies 3.3V or 1, and low signifies 0V or ground.

Step 4: Controlling GPIO with Python

Now that we have a basic understanding of GPIO, let’s start controlling the GPIO pins of the Raspberry Pi using Python.

Open a new Python script in your favorite code editor or IDE.
Import the required modules to work with GPIO:
```
import RPi.GPIO as GPIO
import time
```
The RPi.GPIO module provides access to the GPIO pins, and the time module will be used for adding delays.
Set the GPIO mode and numbering scheme:
```
GPIO.setmode(GPIO.BCM)
```
We are using the BCM numbering scheme in this tutorial.
Define the GPIO pins to be used:
```
LED_PIN = 18
BUTTON_PIN = 17
```
Here, we are using GPIO pin 18 for an LED and GPIO pin 17 for a button.

Set up the LED pin as an output and the button pin as an input:

GPIO.setup(LED_PIN, GPIO.OUT)
GPIO.setup(BUTTON_PIN, GPIO.IN)

Now, let’s control the LED based on the button input using a loop:
```
while True:
    if GPIO.input(BUTTON_PIN):
        GPIO.output(LED_PIN, GPIO.HIGH)
    else:
        GPIO.output(LED_PIN, GPIO.LOW)
```
This code continuously checks if the button is pressed. If the button is pressed, it turns on the LED; otherwise, it turns off the LED.

That’s it! You have successfully controlled the GPIO pins of Raspberry Pi using Python. You can expand upon this example to build more complex IoT applications with Raspberry Pi.

Conclusion

In this tutorial, we learned how to work with Python and Raspberry Pi to build IoT applications using the GPIO pins. We covered the basics of GPIO, set up the Raspberry Pi, and controlled external devices using Python code. With this knowledge, you can now explore various IoT projects and create your own applications using Python and Raspberry Pi.

Published: 21 March 2022