#include <Adafruit_NeoMatrix.h> // https://github.com/adafruit/Adafruit_NeoMatrix

// offload arrays from RAM to PROGMEM
// #include <avr/pgmspace.h>  // https://github.com/Synapseware/avr/blob/master/include/avr/pgmspace.h

#define LED_PIN 6 // Data pin
#define DISPLAY_WIDTH 56 // 64 is too much for Uno/Nano
#define DISPLAY_HEIGHT 8
#define BRIGHTNESS 255
byte delayMS = 20;

Adafruit_NeoMatrix display = Adafruit_NeoMatrix(
                               DISPLAY_WIDTH, DISPLAY_HEIGHT, LED_PIN,
                               NEO_MATRIX_TOP + // NEO_MATRIX_BOTTOM
                               NEO_MATRIX_LEFT + // NEO_MATRIX_RIGHT
                               NEO_MATRIX_ROWS + // NEO_MATRIX_COLUMNS
                               NEO_MATRIX_PROGRESSIVE, // NEO_MATRIX_ZIGZAG,
                               NEO_GRB + // NEO_RGB
                               NEO_KHZ800 // NEO_KHZ400
                             );

int scroll = display.width();
// char sometext[] = "Never gonna give you up.";
const char sometext[] PROGMEM = // single, flat array of char
  "Never "
  "Gonna "
  "Give "
  "You "
  "Up ";
int k;
int scrollwidth = sizeof(sometext) * 6; // each character is 5 pixels plus one kern pixel

void setup() {
  Serial.begin(115200);
  display.begin(); // Initialize the display object
  display.setTextWrap(false);
  display.setBrightness(255);
  display.setTextColor(display.Color(255, 255, 255)); // Set text color (white)
}

void loop() {
  scrollText();
}

void scrollText() {
  // Serial.println(scroll);
  display.fillScreen(0);    //Turn off all the LEDs
  display.setCursor(scroll, 0); // start displaying Neopixels at the right edge
  // display.print(sometext); // store Neopixel buffer
  // display.write(pgm_read_byte(sometext + k)); // for PROGMEM
  // display.write(pgm_read_byte(&sometext[k])); // for PROGMEM
  display.write(pgm_read_byte(sometext)); // for PROGMEM
  if ( --scroll < -scrollwidth ) { // width of sizeof(text) scrolls from 32 to -150
    scroll = display.width(); // re-start at the right
  }
  display.show(); // display the Neopixel buffer
  delay(delayMS);
  // k++;
}