Unit HEX / NeoHEX Arduino Tutorial

#include <M5Unified.h>
#include <FastLED.h>

constexpr uint8_t LED_COUNT  = 37;
constexpr uint8_t LED_BRIGHT = 10;
constexpr uint8_t DATA_PIN   = 9; // CoreS3 Port B LED Signal (G9)
constexpr uint16_t UI_BG     = 0x1082;
constexpr uint16_t UI_PANEL  = 0x2104;
constexpr uint16_t UI_HEADER = 0x0349;
constexpr uint16_t UI_MUTED  = 0xBDF7;
CRGB leds[LED_COUNT];
M5Canvas canvas(&M5.Display);
uint8_t hue = 0;
uint32_t last_frame = 0;
uint32_t last_ui = 0;

uint16_t color565(const CRGB& color)
{
    return (static_cast<uint16_t>(color.r & 0xF8) << 8) |
           (static_cast<uint16_t>(color.g & 0xFC) << 3) | (color.b >> 3);
}

void drawStatus(const CRGB& sample)
{
    char led_count[8] = {};
    char brightness[8] = {};
    snprintf(led_count, sizeof(led_count), "%u", LED_COUNT);
    snprintf(brightness, sizeof(brightness), "%u", LED_BRIGHT);

    canvas.fillScreen(UI_BG);
    canvas.fillRect(0, 0, 320, 42, UI_HEADER);
    canvas.setTextDatum(textdatum_t::middle_center);
    canvas.setFont(&fonts::Font4);
    canvas.setTextSize(1);
    canvas.setTextColor(TFT_WHITE, UI_HEADER);
    canvas.drawString("UNIT HEX / NEOHEX", 160, 16);
    canvas.setFont(&fonts::Font2);
    canvas.setTextColor(UI_MUTED, UI_HEADER);
    canvas.drawString("RGB LIGHTING  /  STATUS", 160, 33);

    canvas.fillRoundRect(12, 54, 296, 82, 6, UI_PANEL);
    canvas.drawRoundRect(12, 54, 296, 82, 6, TFT_MAGENTA);
    canvas.fillCircle(52, 95, 25, color565(sample));
    canvas.setTextDatum(textdatum_t::middle_left);
    canvas.setTextColor(TFT_WHITE, UI_PANEL);
    canvas.drawString("RAINBOW RGB EFFECT", 94, 82);
    canvas.setTextColor(UI_MUTED, UI_PANEL);
    canvas.drawString("37 RGB PIXELS", 94, 105);
    canvas.drawString("RAINBOW COLOR FLOW", 94, 123);

    canvas.fillRoundRect(12, 148, 92, 48, 5, UI_PANEL);
    canvas.fillRoundRect(114, 148, 92, 48, 5, UI_PANEL);
    canvas.fillRoundRect(216, 148, 92, 48, 5, UI_PANEL);
    canvas.setTextDatum(textdatum_t::middle_center);
    canvas.setTextColor(UI_MUTED, UI_PANEL);
    canvas.drawString("LEDS", 58, 161);
    canvas.drawString("BRIGHT", 160, 161);
    canvas.drawString("MODE", 262, 161);
    canvas.setTextColor(TFT_WHITE, UI_PANEL);
    canvas.drawString(led_count, 58, 181);
    canvas.drawString(brightness, 160, 181);
    canvas.drawString("AUTO", 262, 181);

    canvas.fillRect(0, 214, 320, 26, UI_HEADER);
    canvas.setTextColor(TFT_WHITE, UI_HEADER);
    canvas.drawString("HEX + NEOHEX  |  CASCADE READY", 160, 227);
    canvas.pushSprite(0, 0);
}

void setup()
{
    M5.begin();
    Serial.begin(115200);
    canvas.setColorDepth(16);
    canvas.createSprite(320, 240);
    FastLED.addLeds<WS2812B, DATA_PIN, GRB>(leds, LED_COUNT)
        .setCorrection(TypicalLEDStrip);
    FastLED.setBrightness(LED_BRIGHT);
    drawStatus(leds[LED_COUNT / 2]);
}

void loop()
{
    if (millis() - last_frame < 20) {
        return;
    }
    last_frame = millis();
    fill_rainbow(leds, LED_COUNT, hue, 7);
    FastLED.show();
    hue++;
    if (millis() - last_ui >= 250) {
        last_ui = millis();
        drawStatus(leds[LED_COUNT / 2]);
    }
}