Published March 28, 2016 © GPL3+

Charlieplexing with Arduino

Charlieplexing extends the limitation of I/O pins of a controller beyond its capability.

BeginnerFull instructions provided1 hour9,043

Things used in this project

Hardware components

Arduino UNO

Resistor 221 ohm

LED (generic)

Hand tools and fabrication machines

Arduino CC

Story

Charlieplexing is that driving lots of LEDs with only a few pins. And in this laboratory experiment we drive 6 LEDs using 3 pins. This method of Charlieplexing uses the tri-state logic capabilities of micro-controllers in order to gain efficiency over traditional multiplexing. This is another form of multiplexing.

Figure 1. Charlieplexed LEDs

As per the above given to the charlieplexed display the following set of routines were written. The following program worked according to the requirement where the LED blinked in the pattern starting from LED1 to LED6.

The formula for Charlieplexing is:

Where n is the number of pins used.

A lookup table was drawn out to identify the pin pattern to light up each LED individually.

PDDR: Port Data Driven Register.

A: Pin 2

B: Pin 3

C: Pin 4

Code

Arduino Code for Charlieplexing

int A = 2;
int B = 3;
int C = 4;

void setup()
{
  pinMode(A, OUTPUT);
  pinMode(B, OUTPUT); 
  pinMode(C, OUTPUT);  

}


/*
* Turn on the given LED
*
* @paramledNum LED to turn on (1..6)
*
*/
void setLED(int ledNum)
{
	if(ledNum == 1)
	{
                pinMode(A, OUTPUT);
                pinMode(B, INPUT);  // changed to input to trigger tri state.
                pinMode(C, OUTPUT); 
  
                digitalWrite(A, HIGH);             
                digitalWrite(C, LOW);
	}

	if(ledNum == 2)
	{
                pinMode(A, OUTPUT);
                pinMode(B, INPUT); 
                pinMode(C, OUTPUT);
                
                digitalWrite(A, LOW);             
                digitalWrite(C, HIGH);
	}

	if(ledNum == 3)
	{ 
                pinMode(A, OUTPUT);
                pinMode(B, OUTPUT);
                pinMode(C, INPUT);
             
                 digitalWrite(A, HIGH);
                 digitalWrite(B, LOW);        
	}

	if(ledNum == 4)
	{
                pinMode(A, OUTPUT);
                pinMode(B, OUTPUT);
                pinMode(C, INPUT);
                
                digitalWrite(A, LOW);
                digitalWrite(B,HIGH);
	}

	if(ledNum == 5)
	{

                pinMode(A, INPUT);
                pinMode(B, OUTPUT);
                pinMode(C, OUTPUT);               

                digitalWrite(B, HIGH);
                digitalWrite(C, LOW);
	}

	if(ledNum == 6)
	{

                pinMode(A, INPUT);
                pinMode(B, OUTPUT);
                pinMode(C, OUTPUT);  

                digitalWrite(B, LOW);
                digitalWrite(C, HIGH);
	}
}

void loop()
{


		
	for(;;)
	{
		setLED(1);
		delay(500);
		setLED(2);
		delay(500);
		setLED(3);
		delay(500);
		setLED(4);
		delay(500);
		setLED(5);
		delay(500);
		setLED(6);
		delay(500);
	}


}

Credits

Lilanka Udawatta

6 projects • 42 followers

I am Electrical and Electronic engineering student, seeking for opportunities to create something that actually matter to the society.

Contact

Comments

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Charlieplexing with Arduino

Things used in this project

Hardware components

Hand tools and fabrication machines

Story

Schematics

Schematic Diagram

Code

Arduino Code for Charlieplexing

Credits

Lilanka Udawatta

Comments

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Charlieplexing with Arduino

Charlieplexing with Arduino

Things used in this project

Hardware components

Hand tools and fabrication machines

Story

Schematics

Schematic Diagram

Code

Arduino Code for Charlieplexing

Credits

Lilanka Udawatta

Comments

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