2.1.5 Tilt Switch¶

Introduction¶

This is a ball tilt-switch with a metal ball inside. It is used to detect inclinations of a small angle.

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	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
Tilt Switch	-

Schematic Diagram¶

Experimental Procedures¶

Step 1: Build the circuit.

Step 2: Change directory.

cd ~/raphael-kit/c/2.1.5/

Step 3: Compile.

gcc 2.1.5_Tilt.c -lwiringPi

Step 4: Run.

sudo ./a.out

Place the tilt vertically, and the green LED will turns on. If you tilt it, “Tilt!” will be printed on the screen and the red LED will lights on. Place it vertically again, and the green LED will turns on again.

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 TiltPin     0
#define Gpin        2
#define Rpin        3

void LED(char* color)
{
    pinMode(Gpin, OUTPUT);
    pinMode(Rpin, OUTPUT);
    if (color == "RED")
    {
        digitalWrite(Rpin, HIGH);
        digitalWrite(Gpin, LOW);
    }
    else if (color == "GREEN")
    {
        digitalWrite(Rpin, LOW);
        digitalWrite(Gpin, HIGH);
    }
    else
        printf("LED Error");
}

int main(void)
{
    if(wiringPiSetup() == -1){ //when initialize wiring failed,print message to screen
        printf("setup wiringPi failed !");
        return 1;
    }

    pinMode(TiltPin, INPUT);
    LED("GREEN");

    while(1){
        if(0 == digitalRead(TiltPin)){
            delay(10);
            if(0 == digitalRead(TiltPin)){
                LED("RED");
                printf("Tilt!\n");
            }
        }
        else if(1 == digitalRead(TiltPin)){
            delay(10);
            if(1 == digitalRead(TiltPin)){
                LED("GREEN");
            }
        }
    }
    return 0;
}

Code Explanation

void LED(char* color)
{
    pinMode(Gpin, OUTPUT);
    pinMode(Rpin, OUTPUT);
    if (color == "RED")
    {
        digitalWrite(Rpin, HIGH);
        digitalWrite(Gpin, LOW);
    }
    else if (color == "GREEN")
    {
        digitalWrite(Rpin, LOW);
        digitalWrite(Gpin, HIGH);
    }
    else
        printf("LED Error");
}

Define a function LED() to turn the two LEDs on or off. If the parameter color is RED, the red LED lights up; similarly, if the parameter color is GREEN, the green LED will turns on.

while(1){
        if(0 == digitalRead(TiltPin)){
            delay(10);
            if(0 == digitalRead(TiltPin)){
                LED("RED");
                printf("Tilt!\n");
            }
        }
        else if(1 == digitalRead(TiltPin)){
            delay(10);
            if(1 == digitalRead(TiltPin)){
                LED("GREEN");
            }
        }
    }

If the read value of tilt switch is 0, it means that the tilt switch is tilted then you write the parameter ”RED” into function LED to get the red LED lighten up; otherwise, the green LED will lit.