Lesson 7 Tilt Switch


The tilt switch used here is a ball one with a metal ball inside. It is used to detect inclinations of a small angle.



Experimental Principle

The principle is very simple. When the switch is tilted in a certain angle, the ball inside rolls down and touches the two contacts connected to the pins outside, thus triggering circuits. Otherwise the ball will stay away from the contacts, thus breaking the circuits.


The schematic diagram:


Experimental Procedures

Step 1: Build the circuit


Step 2: Open the code file.

Step 3: Select the Board and Port.

Step 4: Upload the sketch to the board.

Now, tilt the switch, and the LED attached to pin 13 on Uno board will light up.



Code Analysis 7-1 Whole Code

const int ledPin = 13;      // the led attach to

void setup()


    pinMode(ledPin,OUTPUT); // initialize the ledPin as an output

    pinMode(2,INPUT);       // set pin2 as INPUT

    digitalWrite(2, HIGH);  // set pin2 as HIGH



void loop()


    int digitalVal = digitalRead(2); // Read the value of pin2

    if(HIGH == digitalVal)           // if tilt switch is not breakover


        digitalWrite(ledPin,LOW);    // turn the led off


    else //if tilt switch breakover


        digitalWrite(ledPin,HIGH);   // turn the led on



The whole code are very simple, one pin of the tilt switch is connected to pin2, another pin is connected to GND, when tilt the switch, the two pins of the switch will be connected to GND, then let the LED on the pin13 lights up.