Chapter 9. Controlling Hardware

9.0. Introduction

In this chapter, you come to grips with the control of electronics through the Raspberry Pi’s GPIO connector.

Most of the recipes require the use of solderless breadboard and male-to-female and male-to-male jumper wires (see Recipe 8.10).

9.1. Connecting an LED

Note

Be sure to check out the accompanying video for this recipe at http://razzpisampler.oreilly.com.

Problem

You want to know how to connect an LED to the Raspberry Pi.

Solution

Connect an LED (see Opto-Electronics) to one of the GPIO pins using a 470Ω or 1kΩ series resistor (see Resistors and Capacitors) to limit the current. To make this recipe, you will need:

Figure 9-1 shows how you can wire this using solderless breadboard and male-to-female jumper leads.

Connecting an LED to a Raspberry Pi
Figure 9-1. Connecting an LED to a Raspberry Pi

Having connected the LED, we need to be able to turn it on and off using commands from Python. To do this, follow Recipe 8.3 to install the RPi.GPIO Python library.

Start a Python console (Recipe 5.3) from the Terminal with superuser access and enter these commands:

$ sudo python
>>> import RPi.GPIO as GPIO
>>> GPIO.setmode(GPIO.BCM)
>>> GPIO.setup(18, GPIO.OUT)
>>> GPIO.output(18, True)
>>> GPIO.output(18, False)

This will turn your LED on and off.

Discussion ...

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