Arduino rgb matrix via serial

sketch_rgb_matrix_serial

// Base64 - Version: Latest 
#include <Base64.h>
//#include <base64.hpp>

// FastLED - Version: Latest 
#include <FastLED.h>
#define LED_PIN 2
#define MATRIX_WIDTH 8
#define MATRIX_HEIGHT 8
// #define NUM_LEDS 64
#define NUM_LEDS 128
#define BRIGHTNESS  12
#define LED_TYPE    WS2811
#define COLOR_ORDER GRB

CRGB leds[NUM_LEDS];

char rainbow2[] = "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";

void setup() {
  delay(3000);
  FastLED.addLeds<LED_TYPE, LED_PIN, COLOR_ORDER>(leds, NUM_LEDS);
  FastLED.setBrightness(BRIGHTNESS);
  
  patternBase64(rainbow2);
  FastLED.show();
  
  Serial.begin(38400);
  while (!Serial) {
    ; // wait for serial port to connect. Needed for native USB port only
  }
  Serial.println("rgb matrix via serial by FrankkieNL");
}

void loop() {
  //Read a whole strip's worth of RGB data directly into the leds array at once
  //https://github.com/FastLED/FastLED/wiki/Controlling-leds#read-rgb-data-from-serial
  //Serial.readBytes( (char*)leds, NUM_LEDS * 3);
  if (Serial.available()){
    Serial.readBytes( (char*)leds, NUM_LEDS * 3);
    FastLED.show();
  }
}


void patternBase64(char inputString[]) {
  int decodedLength = Base64.decodedLength(inputString, strlen(inputString));
  char decodedString[decodedLength];
  Base64.decode(decodedString, inputString, strlen(inputString));
  for (int i = 0; i < decodedLength; i+=3) {
    leds[i/3] = CRGB(decodedString[i],decodedString[i+1],decodedString[i+2]);
  }
}