PROJECT: Hold Button To Turn LED On
Step 1 - Build the Project

This code ties two conditions together- the button’s condition is directly related to the LED’s condition. Because each of them is using only digital logic, there are only two condition (HIGH or LOW) for the button and for the LED.

Step 2 - Upload the Code

/* * Button held on pin A5 turns LED attached to pin 11 on */ void setup(){ pinMode(11, OUTPUT); //LED pin pinMode(A5, INPUT_PULLUP); //pushbutton pin } void loop(){ //if the pushbutton is pressed, hold the LED on if (digitalRead(A5) == LOW){ digitalWrite(11, HIGH); } else { digitalWrite(11,LOW); //otherwise, turn LED off } } // Try to add an LED to the code & when the button is pressed, both are on // (c) 2017 Let's Start Coding. License: www.letsstartcoding.com/bsdlicense
 

Step 3 - Read the Walkthrough

Because the pushbutton is setup as an INPUT_PULLUP, it will digitalRead LOW when it is pressed. To make the light illuminate when the button is pressed, you need to tie digitalRead LOW to digitalWrite HIGH in the ‘if’ statement.

The else statement says “If the ‘if’ statement isn’t true, do this section of code.” Because the button can only be pressed or unpressed, the else is very straightforward.

It looks like this code isn’t doing much when you use it, but remember that the loop is being run hundreds of times a minute, so the reaction to the button press will be very fast!