# Julia Burch's Labs

## Lab 4

### Lesson One

```/* * Blink * * The basic Arduino example. Turns on an LED on for 1/10 of a second, * then off for 9/10 of a second, and so on... We use pin 13 because, * depending on your Arduino board, it has either a built-in LED * or a built-in resistor so that you need only an LED. * * http://www.arduino.cc/en/Tutorial/Blink */ int ledPin = 13; // LED connected to digital pin 13 void setup() // run once, when the sketch starts { pinMode(ledPin, OUTPUT); // sets the digital pin as output } void loop() // run over and over again { digitalWrite(ledPin, HIGH); // sets the LED on delay(100); // waits for 1/10 of a second digitalWrite(ledPin, LOW); // sets the LED off delay(900); // waits for 9/10 of a second } ```

### Lesson Two

• Exercise 1 Modify the code so that the light is on for 100 msec and off for 900 msec.
• Exercise 2 Modify the code so that the light is on for 50 msec and off for 50 msec. What happens? 'The light begins to blink very rapidly.'
• Exercise 3 Modify the code so that the light is on for 10 ms and off for 10 ms. What happens? 'The light does not appear to blink.'
• Exercise 4 Now pick up the Arduino and gently wave it back and forth, in a dark room. What happens? 'The light trails dashes through the air as you wave the Arduino back and forth.'
• Exercise 5 What do you think is happening here? 'This occurs because the Arduino is blinking, it is just occurring too quickly for our eyes to perceive.'

### Lesson Four

#### Hello World!

```/* * Hello World! * * This is the Hello World! for Arduino. * It shows how to send data to the computer */ void setup() // run once, when the sketch starts { Serial.begin(9600); // set up Serial library at 9600 bps } void loop() // run over and over again { Serial.println("Hello world!"); // prints hello with ending line break delay(1000); } ```

#### Have Some Math!

```/* * Math is fun! */ int a = 5; int b = 10; int c = 20; void setup() // run once, when the sketch starts { Serial.begin(9600); // set up Serial library at 9600 bps Serial.println("Here is some math: "); Serial.print("a = "); Serial.println(a); Serial.print("b = "); Serial.println(b); Serial.print("c = "); Serial.println(c); Serial.print("a + b = "); // add Serial.println(a + b); Serial.print("a * c = "); // multiply Serial.println(a * c); Serial.print("c / b = "); // divide Serial.println(c / b); Serial.print("b - c = "); // subtract Serial.println(b - c); } void loop() // we need this to be here even though its empty { } ```