2.1.4 Slide Switch

Introduction

In this project, we will learn how to use a slide switch. Usually,the slide switch is soldered on PCB as a power switch, but here we need to insert it into the breadboard, thus it may not be tightened. And we use it on the breadboard to show its function.

Required Components

In this project, we need the following components.

../_images/list_2.1.2_slide_switch.png

It’s definitely convenient to buy a whole kit, here’s the link:

Name

ITEMS IN THIS KIT

LINK

Raphael Kit

337

Raphael Kit

You can also buy them separately from the links below.

COMPONENT INTRODUCTION

PURCHASE LINK

GPIO Extension Board

BUY

Breadboard

BUY

Jumper Wires

BUY

Resistor

BUY

LED

BUY

Slide Switch

BUY

Capacitor

BUY

Schematic Diagram

Connect the middle pin of the Slide Switch to GPIO17, and two LEDs to pin GPIO22 and GPIO27 respectively. Then when you pull the slide, you can see the two LEDs light up alternately.

../_images/image305.png ../_images/image306.png

Experimental Procedures

Step 1: Build the circuit.

../_images/image161.png

Step 2: Go to the folder of the code.

cd ~/raphael-kit/c/2.1.4

Step 3: Compile.

gcc 2.1.4_Slider.c -lwiringPi

Step 4: Run the executable file above.

sudo ./a.out

While the code is running, get the switch connected to the left, then the yellow LED lights up; to the right, the red light turns on.

Note

If it does not work after running, or there is an error prompt: "wiringPi.h: No such file or directory", please refer to Install and Check the WiringPi.

Code

#include <wiringPi.h>
#include <stdio.h>
#define slidePin        0
#define led1            3
#define led2            2

int main(void)
{
    // When initialize wiring failed, print message to screen
    if(wiringPiSetup() == -1){
        printf("setup wiringPi failed !");
        return 1;
    }
    pinMode(slidePin, INPUT);
    pinMode(led1, OUTPUT);
    pinMode(led2, OUTPUT);
    while(1){
        // slide switch high, led1 on
        if(digitalRead(slidePin) == 1){
            digitalWrite(led1, LOW);
            digitalWrite(led2, HIGH);
            printf("LED1 on\n");
        }
        // slide switch low, led2 on
        if(digitalRead(slidePin) == 0){
            digitalWrite(led2, LOW);
            digitalWrite(led1, HIGH);
            printf(".....LED2 on\n");
        }
    }
    return 0;
}

Code Explanation

if(digitalRead(slidePin) == 1){
            digitalWrite(led1, LOW);
            digitalWrite(led2, HIGH);
            printf("LED1 on\n");
    }

When the slide is pulled to the right, the middle pin and right one are connected; the Raspberry Pi reads a high level at the middle pin, so the LED1 is on and LED2 off

if(digitalRead(slidePin) == 0){
            digitalWrite(led2, LOW);
            digitalWrite(led1, HIGH);
            printf(".....LED2 on\n");
        }

When the slide is pulled to the left, the middle pin and left one are connected; the Raspberry Pi reads a low, so the LED2 is on and LED1 off

Phenomenon Picture

../_images/image162.jpeg