Project 1.04 Pulse LED

This project demonstrates the full range of the analogWrite function, and how that can be used to create a pulsing effect.

Project Code:

/////////////////////////////////////////////////
// 1.04 - Pulse LED

byte LED1 = 13;

void setup() {
  pinMode(LED1, OUTPUT);
}

void loop() {
  byte wait = 10; 

  for (int i = 0; i < 255; i++) {
    analogWrite(LED1, i);
    delay(wait);
  }

  for (int i = 255; i > 0; i--) {
    analogWrite(LED1, i);
    delay(wait);
  }
}
/////////////////////////////////////////////////

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*If you’re copying and pasting the code, or typing from scratch, delete everything out of a new Arduino sketch and paste / type in the above text.

Before we jump into the code let’s take a look at what a for-loop is. A for-loop is a way to repeat a chunk of code a specified number of times. See the table below for a breakdown of a for-loop structure:

Part	Description
for	Loop type
i < 255;	This is a conditional. The for-loop will continue to run while this is true. In this case, i is less than 255
i++	This increments the i variable by 1 every time the loop executes
{ analogWrite(LED1, i); delay(wait); }	This is the code that runs every time the loop executes

for-loops can be a foreign concept. For a video explanation please visit:

https://www.youtube.com/watch?v=b4DPj0XAfSg

Here in the program a for-loop is used to count 0 – 255, slowly increasing the brightness of the LED. The index of the for-loop ( i ) is passed to the analogWrite function as the for-loop loops. A small delay is added after each analogWrite so the changes can be perceived by the human eye.

for (int i = 0; i < 255; i++) {
  analogWrite(LED1, i);
  delay(wait);
}

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Here the program counts down 255 – 0, slowly decreasing the brightness of the LED.

for (int i = 0; i < 255; i++) {
  analogWrite(LED1, i);    
  delay(wait);
}

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