CharlieplexCalc

A Python script that calculates charlieplexing pinouts and logic tables.

Run the script with the desired number of LEDs to drive (up to 999), and it will output the pinouts, logic table, and Ardunio code header to help you set up and program your CharliePlexed LEDs.

Usage

charlie.py <numleds>

e.g > python charlie.py 12

Output

You need 4 pins to drive 12 LEDs
[You could drive a maximum of 12 LEDs with 4 pins]

Pin   1 >    1-   2+   5-   6+  11-  12+
Pin   2 >    1+   2-   3-   4+   9-  10+
Pin   3 >    3+   4-   5+   6-   7-   8+
Pin   4 >    7+   8-   9+  10-  11+  12-

Logic table     1    2    3    4
Led   1   >    LO   HI   IN   IN
Led   2   >    HI   LO   IN   IN
Led   3   >    IN   LO   HI   IN
Led   4   >    IN   HI   LO   IN
Led   5   >    LO   IN   HI   IN
Led   6   >    HI   IN   LO   IN
Led   7   >    IN   IN   LO   HI
Led   8   >    IN   IN   HI   LO
Led   9   >    IN   LO   IN   HI
Led  10   >    IN   HI   IN   LO
Led  11   >    LO   IN   IN   HI
Led  12   >    HI   IN   IN   LO

int numPins = 4;
int numLeds = 12;
byte	ledPins[][4] ={
	{ 0,1,2,2 },
	{ 1,0,2,2 },
	{ 2,0,1,2 },
	{ 2,1,0,2 },
	{ 0,2,1,2 },
	{ 1,2,0,2 },
	{ 2,2,0,1 },
	{ 2,2,1,0 },
	{ 2,0,2,1 },
	{ 2,1,2,0 },
	{ 0,2,2,1 },
	{ 1,2,2,0 },
	};

Programming

Use the genetrated code in your Arduino project, and for each LED read the table to determine the status of each pin where 0 is LOW, 1 is HIGH, and 2 is configured for INPUT, use pinMode().

Here's an example main loop()

int pins[] = {8,7,6,5}; // Mapping of actual micro's pin numbers to the virtual pins

void loop(){
  // cycle through the LEDs
  for(int l=0; l<numLeds; l++){
    for(int p=0; p<numPins; p++){
      byte data = ledPins[l][p];
      
      if( data == 2 ){
        pinMode( pins[p], INPUT );
      }else{
        pinMode( pins[p], OUTPUT );
        digitalWrite( pins[p], data );
      } 
    }
  }
  delay(40);
}