Interlaced scrolling with NeoPixel+Arduino proof of concept

interlacedScroll.c

// Proof of concept for using horizontal interlacing with scrolling text to improve resolution.

#include <Adafruit_GFX.h>

#include <gamma.h>

#include <Adafruit_NeoMatrix.h>
#include <Adafruit_NeoPixel.h>

#ifndef PSTR
 #define PSTR // Make Arduino Due happy
#endif

#define PIN 6

#define ROWS 6
#define COLUMNS 22
// number of pixels to skip, use -1 for no interlacing.
#define SKIP -2
#define WAIT 10w

// matrix instead
Adafruit_NeoMatrix matrix = Adafruit_NeoMatrix(COLUMNS, ROWS, PIN,
  NEO_MATRIX_TOP     + NEO_MATRIX_RIGHT +
  NEO_MATRIX_COLUMNS + NEO_MATRIX_ZIGZAG,
  NEO_GRB            + NEO_KHZ800);

// raw data for scroll. later versions will have text and a font

uint32_t onColor = matrix.Color(60, 40, 20);
uint32_t offColor = matrix.Color(0, 0, 15);

const byte idea[] = {
  0b00111100,
  0b00111110,
  0b00010011,
  0b00010011,
  0b00111110,
  0b00111100,
  0,0,
  0b00111111,
  0b00111111,
  0b00100101,
  0b00100101,
  0b00111111,
  0b00011010,
  0,0,
  0b00011110,
  0b00111111,
  0b00100001,
  0b00100001,
  0b00110011,
  0b00010010,
  0,0,
  0b00111111,
  0b00111111,
  0b00100001,
  0b00110011,
  0b00011110,
  0b00001100,
  0,0,
  0b00010010,
  0b00111010,
  0b00101010,
  0b00101010,
  0b00111110,
  0b00111100,
  0,0,
  0b00111111,
  0b00111111,
  0b00100100,
  0b00100100,
  0b00111100,
  0b00011000,
  0,0,
  0b00011100,
  0b00111110,
  0b00100010,
  0b00100010,
  0b00100010,
  0b00100010,
  0,0,
  0b00011000,
  0b00111100,
  0b00100100,
  0b00100100,
  0b00111111,
  0b00111111,
  0,0,
};


// IMPORTANT: To reduce NeoPixel burnout risk, add 1000 uF capacitor across
// pixel power leads, add 300 - 500 Ohm resistor on first pixel's data input
// and minimize distance between Arduino and first pixel.  Avoid connecting
// on a live circuit...if you must, connect GND first.

void setup() {
  matrix.begin();
  matrix.show();
}

void loop() {
  for( int sourceColumn = 0; sourceColumn < sizeof(idea); sourceColumn++) {
    int renderSource = sourceColumn;
    for( int renderColumn = 0; renderColumn < COLUMNS; renderColumn++ ) {
      renderSource = (renderSource + SKIP) % sizeof(idea);
      renderByteAtColumn( idea[renderSource], renderColumn );
    }
    matrix.show();
    delay(WAIT);
  }
}

// TODO: replace this method with the proper matrix call.
int pixelLocation(int col, int row) {
  if( row & 1 ) {
    return (row+1) * COLUMNS - (col +1 );
  } else {
    return row * COLUMNS + col;
  }
}

void renderByteAtColumn( byte pixels, int column ) {
  for(int row=0; row<ROWS; row++) {
    int location = pixelLocation( column, row );
    if( pixels & ( 1 << row) ) {
      matrix.setPixelColor(location, onColor);
    } else {
      matrix.setPixelColor(location, offColor);
    }
  }
}