led_blink.ino

// Let's write a program that blinks an LED on and off forever!

// An Arduino program always has two main parts: setup() and loop().

// setup() is a function that gets run a single time at the start of the program.
// We usually use it to do "initialization", which basically means "stuff
// we have to do at the start of the program so that the rest of the program works right."




void setup() {
  // In this program, the only initialization we need to do is this line:
  pinMode(A0, OUTPUT);

  // That line tells the Arduino system that our program will be using pin A0 as an _output_.

  ////// Pin numbers

  // A0 is the pin that our LED is attached to.
  // If your LED is attached to a different pin, then either move it to pin A0,
  // or change the pinMode() line to refer to the right pin (e.g. pin A3 or whatever).

  ////// Input vs output

  // Your program can use any pin as either an "input" or an "output".

  // Inputs are things like sensors. When you use sensors, you attach them to your
  // Arduino and then you write code that checks the value of the sensors -
  // in this way, your program can figure out e.g. what the current temperature is.
  // Inputs are things that your program _reads from_.

  // Outputs are things like LEDs, or speakers, or motors.
  // Outputs are thing that your program _controls_.
}




// loop() is a function that gets run over and over again until you turn your Arduino off.
// If you want your program to do something over and over again, you'll want to put that code in loop().

void loop() {
  // Let's start by turning the LED on!
  // This line of code sets pin A0's voltage level to "high", which causes the LED to light up.
  digitalWrite(A0, HIGH);

  // Now let's wait for a second before we turn the LED off again.
  delay(1000);

  // delay() is a function that takes a number of milliseconds and pauses the program
  // for that long - so if I write delay(500), the program will stop doing anything
  // for 0.5 seconds.

  // Now let's turn the LED off by setting its voltage level to "low"...
  digitalWrite(A0, LOW);

  // ...and then let's wait for another second.
  delay(1000);

  // After this delay(1000) call is done, this loop() function is over.
  // But the Arduino system will automatically run it again, over and over, until you turn off your Arduino!
  // That's why the light will keep blinking on and off. Does that make sense?
}

// That's it, that's the whole program!
// To make the light blink faster or slower, try changing the number your program passes to delay()!