Using loops for the LED examples

In the last example – http://www.mikroblog.net/arduino/arduino-basics/more-arduino-and-led-examples.php we showed you some examples of flashing multiple LEDs, now this code worked OK but there is a more efficient way of doing the same action. We use loops to initialize the LEDs and then again for switching the LEDs on and off. There are 3 different types of loop and we will show the same example for all 3 of them.

 

Parts List

1 x Arduino UNO
7 x Leds
7 x 220ohm resistors

Schematic

Example 1 : Use a for loop to initialize the pins as outputs and also cycle through the LEDs one at a time from 2 to 8
[codesyntax lang=”cpp”]

#define myDelay 500

void setup() 
{
// initialize the digital pins as outputs:
for (int i = 2; i<=8 ; i++) 
{
pinMode(i, OUTPUT);
}
}

void loop() 
{
for (int i = 2; i<=8; i++) 
{ // blink LEDs on pins 2 to 8
digitalWrite(i, HIGH);
delay(myDelay);
digitalWrite(i, LOW);
}
}

[/codesyntax]

 

Example 2 : reverse it, going from 8 to 2

 

[codesyntax lang=”cpp”]

#define myDelay 500

void setup() 
{
// initialize the digital pins as outputs:
for (int i = 2; i<=8 ; i++) 
{
pinMode(i, OUTPUT);
}
}

void loop() 
{
for (int i = 8; i>=2; i--) 
{ // blink from LEDs 8 to 2
digitalWrite(i, HIGH);
delay(myDelay);
digitalWrite(i, LOW);
}
}

[/codesyntax]

 

Example 3 : You can also use a Do While loop, here is the example above again. the concept again is simple we set  the variable i to be 8, we then decrement this (subtract) by 1 every time. When i is equal to 2 the loop will exit and start again at 8.

 

[codesyntax lang=”cpp”]

#define myDelay 500

void setup() 
{
// initialize the digital pins as outputs:
for (int i = 2; i<=8 ; i++) 
{
pinMode(i, OUTPUT);
}
}

void loop() 
{
int i = 8;
do{
digitalWrite(i, HIGH);
delay(myDelay);
digitalWrite(i, LOW);
i--;
}while(i>=2);
}

[/codesyntax]

 
Example 4 : A while loop this time, same concept as above.

 

[codesyntax lang=”cpp”]

#define myDelay 500

void setup() 
{
// initialize the digital pins as outputs:
for (int i = 2; i<=8 ; i++) 
{
pinMode(i, OUTPUT);
}
}

void loop() 
{

int i = 8;

while(i>=2)
{
digitalWrite(i, HIGH);
delay(myDelay);
digitalWrite(i, LOW);
i--;
}
}

[/codesyntax]

 

 

 

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