Multi-Display Digital Clock

#include <Arduino.h>
#include <SPI.h>
#include <WiFi.h>
#include <time.h>
#include <Adafruit_GFX.h>
#if defined(ESP32)
#include <Fonts/FreeSansBold24pt7b.h>
#endif
#include <Adafruit_GC9A01A.h>


// Forward declarations

// Forward declarations
void prepareText(Adafruit_GC9A01A &screen, uint16_t color, uint8_t size);
void finishText(Adafruit_GC9A01A &screen);
void drawRollingText(Adafruit_GC9A01A &screen, const char *oldText, const char *newText, uint16_t color, uint8_t size, bool animate);

void drawCentered(Adafruit_GC9A01A &screen, const char *text, uint16_t color, uint8_t size);
void drawDigit(Adafruit_GC9A01A &screen, char digit, bool secondsScreen);
void showTime(const tm &now);
void showDate(const tm &now);
void showStatus(const char *message, uint16_t color);
bool connectAndUpdateTime();

// Enter your Wi-Fi details here before deploying if you want automatic time updates.
constexpr char WIFI_SSID[] = "YOUR_WIFI_NAME";
constexpr char WIFI_PASSWORD[] = "YOUR_WIFI_PASSWORD";
constexpr char IRELAND_TIME_ZONE[] = "GMT0BST,M3.5.0/1,M10.5.0/2";
constexpr uint32_t TIME_SYNC_INTERVAL_MS = 60UL * 60UL * 1000UL;

constexpr int TFT_SCK = 18;
constexpr int TFT_MOSI = 23;
constexpr int TFT1_CS = 4;
constexpr int TFT1_DC = 25;
constexpr int TFT2_CS = 13;
constexpr int TFT2_DC = 26;
constexpr int TFT3_CS = 14;
constexpr int TFT3_DC = 27;
constexpr int TFT4_CS = 16;
constexpr int TFT4_DC = 32;
constexpr int TFT5_CS = 17;
constexpr int TFT5_DC = 33;

Adafruit_GC9A01A screen1(TFT1_CS, TFT1_DC, -1);
Adafruit_GC9A01A screen2(TFT2_CS, TFT2_DC, -1);
Adafruit_GC9A01A screen3(TFT3_CS, TFT3_DC, -1);
Adafruit_GC9A01A screen4(TFT4_CS, TFT4_DC, -1);
Adafruit_GC9A01A screen5(TFT5_CS, TFT5_DC, -1);
Adafruit_GC9A01A *screens[] = {&screen1, &screen2, &screen3, &screen4, &screen5};

char lastShown[4] = {'\0', '\0', '\0', '\0'};
int lastSeconds = -1;
uint32_t lastTimePollMs = 0;
uint32_t lastTimeSyncMs = 0;
bool showingDate = false;

constexpr uint8_t ROLLER_FRAMES = 8;
constexpr uint16_t ROLLER_FRAME_MS = 50;

void prepareText(Adafruit_GC9A01A &screen, uint16_t color, uint8_t size) {
  screen.setTextWrap(false);
#if defined(ESP32)
  screen.setFont(&FreeSansBold24pt7b);
#endif
  screen.setTextSize(size);
  screen.setTextColor(color);
}

void finishText(Adafruit_GC9A01A &screen) {
#if defined(ESP32)
  screen.setFont(nullptr);
#endif
}

void drawCentered(Adafruit_GC9A01A &screen, const char *text, uint16_t color, uint8_t size) {
  screen.fillScreen(GC9A01A_BLACK);
  prepareText(screen, color, size);
  int16_t x1, y1;
  uint16_t width, height;
  screen.getTextBounds(text, 0, 0, &x1, &y1, &width, &height);
  screen.setCursor((240 - width) / 2 - x1, (240 - height) / 2 - y1);
  screen.print(text);
  finishText(screen);
}

void drawRollingText(Adafruit_GC9A01A &screen, const char *oldText, const char *newText,
                     uint16_t color, uint8_t size, bool animate) {
  prepareText(screen, color, size);
  int16_t x1, y1;
  uint16_t width, height;
  screen.getTextBounds(newText, 0, 0, &x1, &y1, &width, &height);
  const int16_t x = (240 - width) / 2 - x1;
  const int16_t centreY = (240 - height) / 2 - y1;

  const uint8_t frames = animate ? ROLLER_FRAMES : 1;
  for (uint8_t frame = 1; frame <= frames; ++frame) {
    const int16_t travel = (240 * frame) / frames;
    screen.fillScreen(GC9A01A_BLACK);
    if (animate) {
      screen.setCursor(x, centreY - travel);
      screen.print(oldText);
    }
    screen.setCursor(x, centreY + 240 - travel);
    screen.print(newText);
    if (animate) {
      delay(ROLLER_FRAME_MS);
    }
  }
  finishText(screen);
}

void showTime(const tm &now) {
  char digits[4] = {
    static_cast<char>('0' + now.tm_hour / 10),
    static_cast<char>('0' + now.tm_hour % 10),
    static_cast<char>('0' + now.tm_min / 10),
    static_cast<char>('0' + now.tm_min % 10)
  };

  for (int i = 0; i < 4; ++i) {
    if (digits[i] != lastShown[i]) {
      char oldText[2] = {lastShown[i] == '\0' ? digits[i] : lastShown[i], '\0'};
      char newText[2] = {digits[i], '\0'};
      drawRollingText(*screens[i], oldText, newText, GC9A01A_WHITE, 5, lastShown[i] != '\0');
      lastShown[i] = digits[i];
    }
  }

  if (now.tm_sec != lastSeconds) {
    char oldText[3];
    char newText[3];
    snprintf(oldText, sizeof(oldText), "%02d", lastSeconds < 0 ? now.tm_sec : lastSeconds);
    snprintf(newText, sizeof(newText), "%02d", now.tm_sec);
    drawRollingText(*screens[4], oldText, newText, GC9A01A_CYAN, 3, lastSeconds >= 0);
    lastSeconds = now.tm_sec;
  }
}

void showDate(const tm &now) {
  char day[3];
  char month[3];
  char year[5];
  snprintf(day, sizeof(day), "%02d", now.tm_mday);
  snprintf(month, sizeof(month), "%02d", now.tm_mon + 1);
  snprintf(year, sizeof(year), "%04d", now.tm_year + 1900);

  drawCentered(*screens[0], day, GC9A01A_GREEN, 5);
  drawCentered(*screens[1], day, GC9A01A_GREEN, 5);
  drawCentered(*screens[2], month, GC9A01A_GREEN, 5);
  drawCentered(*screens[3], month, GC9A01A_GREEN, 5);

  screen5.fillScreen(GC9A01A_BLACK);
  screen5.setTextWrap(false);
#if defined(ESP32)
  screen5.setFont(&FreeSansBold24pt7b);
#endif
  screen5.setTextSize(2);
  screen5.setTextColor(GC9A01A_GREEN);
  int16_t x1, y1;
  uint16_t width, height;
  screen5.getTextBounds(year, 0, 0, &x1, &y1, &width, &height);
  screen5.setCursor((240 - width) / 2 - x1, (240 - height) / 2 - y1);
  screen5.print(year);
#if defined(ESP32)
  screen5.setFont(nullptr);
#endif
}

void showStatus(const char *message, uint16_t color) {
  for (Adafruit_GC9A01A *screen : screens) {
    drawCentered(*screen, message, color, 2);
  }
}

bool connectAndUpdateTime() {
  WiFi.mode(WIFI_STA);
  WiFi.begin(WIFI_SSID, WIFI_PASSWORD);

  uint32_t startMs = millis();
  while (WiFi.status() != WL_CONNECTED && millis() - startMs < 20000) {
    delay(250);
  }
  if (WiFi.status() != WL_CONNECTED) {
    WiFi.disconnect(true);
    WiFi.mode(WIFI_OFF);
    return false;
  }

  configTzTime(IRELAND_TIME_ZONE, "pool.ntp.org", "time.nist.gov");
  tm timeInfo;
  bool gotTime = getLocalTime(&timeInfo, 15000);
  WiFi.disconnect(true);
  WiFi.mode(WIFI_OFF);

  if (gotTime) {
    lastTimeSyncMs = millis();
  }
  return gotTime;
}

void setup() {
  Serial.begin(115200);
#if defined(ESP32)
  SPI.begin(TFT_SCK, -1, TFT_MOSI);
#else
  SPI.begin();
#endif

  for (Adafruit_GC9A01A *screen : screens) {
    screen->begin();
    screen->setRotation(2);
    screen->fillScreen(GC9A01A_BLACK);
  }

  showStatus("WiFi", GC9A01A_YELLOW);
  if (!connectAndUpdateTime()) {
    showStatus("NO NET", GC9A01A_RED);
  }
}

void loop() {
  if (millis() - lastTimeSyncMs >= TIME_SYNC_INTERVAL_MS) {
    connectAndUpdateTime();
  }

  if (millis() - lastTimePollMs < 200) {
    return;
  }
  lastTimePollMs = millis();

  tm now;
  if (getLocalTime(&now, 50)) {
    const bool dateWindow = now.tm_sec == 30;
    if (dateWindow) {
      if (!showingDate) {
        showDate(now);
        showingDate = true;
      }
    } else {
      if (showingDate) {
        for (char &shown : lastShown) {
          shown = '\0';
        }
        showingDate = false;
      }
      showTime(now);
    }
  }
}