Chapter 12. Digital Inputs

12.0 Introduction

In this chapter, you look at recipes for using digital inputs, such as switches and keypads. This chapter also covers modules that have a digital output that can be connected to a Raspberry Pi GPIO input.

Most of the recipes require the use of a solderless breadboard and jumper wires (see Recipe 9.8).

12.1 Connecting a Push Switch

Note

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

Problem

You want to connect a switch to your Raspberry Pi so that when you press it, some Python code is run.

Solution

Connect a switch to a GPIO pin and use the RPi.GPIO library in your Python program to detect the button press.

To make this recipe, you will need:

Figure 12-1 shows how to connect a tactile push switch using a breadboard and jumper wires.

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Figure 12-1. Connecting a push switch to a Raspberry Pi

An alternative to using a breadboard and tactile switch is to use a Squid Button (Figure 12-2). This is a push switch with female header leads soldered to the end, which can be connected directly to a the GPIO connector (Recipe 9.11).

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Figure 12-2. A Squid Button

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