Joey’s Arduino Homework 2

Digital Input




  Turns on and off a light emitting diode(LED) connected to digital pin 13,

  when pressing a pushbutton attached to pin 2.

  The circuit:

  – LED attached from pin 13 to ground

  – pushbutton attached to pin 2 from +5V

  – 10K resistor attached to pin 2 from ground

  – Note: on most Arduinos there is already an LED on the board

    attached to pin 13.


// constants won’t change. They’re used here to set pin numbers:

const int buttonPin = 2;     // the number of the pushbutton pin

const int ledPin =  13;      // the number of the LED pin

// variables will change:

int buttonState = 0;         // variable for reading the pushbutton status

void setup() {

  // initialize the LED pin as an output:

  pinMode(ledPin, OUTPUT);

  // initialize the pushbutton pin as an input:

  pinMode(buttonPin, INPUT);


void loop() {

  // read the state of the pushbutton value:

  buttonState = digitalRead(buttonPin);

  // check if the pushbutton is pressed. If it is, the buttonState is LOW:

  if (buttonState == LOW) {

    // turn LED on:

    digitalWrite(ledPin, HIGH);

  } else {

    // turn LED off:

    digitalWrite(ledPin, LOW);




The Serial Analog Input



  Analog input, analog output, serial output

  Reads an analog input pin, maps the result to a range from 0 to 255 and uses

  the result to set the pulse width modulation (PWM) of an output pin.

  Also prints the results to the Serial Monitor.

  The circuit:

  – potentiometer connected to analog pin 0.

    Center pin of the potentiometer goes to the analog pin.

    side pins of the potentiometer go to +5V and ground

  – LED connected from digital pin 9 to ground


// These constants won’t change. They’re used to give names to the pins used:

const int analogInPin = A0;  // Analog input pin that the potentiometer is attached to

const int analogOutPin = 9; // Analog output pin that the LED is attached to

int sensorValue = 0;        // value read from the pot

int outputValue = 0;        // value output to the PWM (analog out)

void setup() {

  // initialize serial communications at 9600 bps:



void loop() {

  // read the analog in value:

  sensorValue = analogRead(analogInPin);

  // map it to the range of the analog out:

  outputValue = map(sensorValue, 0, 1023, 0, 255);

  // change the analog out value:

  analogWrite(analogOutPin, outputValue);

  // print the results to the Serial Monitor:

  Serial.print(“sensor = “);


  Serial.print(“\t output = “);


  // wait 2 milliseconds before the next loop for the analog-to-digital

  // converter to settle after the last reading:




Two buttons control one LED (lighter and off)

It does not work?

Author: Joey

Hi I am Joey, I am from china.

One thought on “Joey’s Arduino Homework 2”

  1. Hi Joey, I can’t see your videos because they are set to private, would you please change the youtube permissions to “unlisted” or “public”? Thanks!

Comments are closed.