M5 Fader unit: LED out 2

main.cpp

#include <Arduino.h>
#include <FastLED.h>

constexpr int pin_fader = 33;
constexpr int pin_led = 32;

constexpr int led_count = 14;
CRGB leds[led_count];
long show = 0;

void setup() {
  ::pinMode(pin_fader, INPUT);
  FastLED.addLeds<NEOPIXEL, pin_led>(leds, led_count);
  FastLED.setBrightness(64);
}

void loop() {
  constexpr int left[] =  {  0,  1,  2,  3,  4,  5,  6 };
  constexpr int right[] = { 13, 12, 11, 10,  9,  8,  7 };

  auto adc = ::analogRead(pin_fader);
  auto n = map(adc, 0, 4095, 7, 0);
  if (show == n) {
    return;
  }
  show = n;
  int i;
  for (i = 0; i < show; ++i)
    leds[left[i]] = leds[right[i]] = CRGB::Black;
  for (; i < 7; ++i)
    leds[left[i]] = leds[right[i]] = CRGB::White;

  FastLED.show();
}