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.
It’s definitely convenient to buy a whole kit, here’s the link:
Name |
ITEMS IN THIS KIT |
LINK |
---|---|---|
Raphael Kit |
337 |
You can also buy them separately from the links below.
COMPONENT INTRODUCTION |
PURCHASE LINK |
---|---|
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.
Experimental Procedures¶
Step 1: Build the circuit.
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