How to Build the Tellaprompter with an ESP32 and ILI9341 Touchscreen

#include <Arduino.h>
// Teleprompter for ESP32 + ILI9341 TFT + XPT2046 Touch + Push Button
// Button (GPIO21): pause/resume scrolling
// Touch screen: tap left half = slower, tap right half = faster

#include <SPI.h>
#include <Adafruit_GFX.h>
#include <Adafruit_ILI9341.h>
#include <XPT2046_Touchscreen.h>

// Pin definitions
#define TFT_CS   4
#define TFT_DC   27
#define TFT_RST  32
#define TFT_BL   16
#define TOUCH_CS 13
#define TOUCH_IRQ 14
#define BUTTON_PIN 21

// Display dimensions
#define SCREEN_W 240
#define SCREEN_H 320

// Text settings
#define TEXT_SIZE    2
#define CHAR_H       16   // 8px * TEXT_SIZE
#define LINE_SPACING 2
#define ROW_H        (CHAR_H + LINE_SPACING)
#define CHARS_PER_LINE 20 // SCREEN_W / (6 * TEXT_SIZE)

// Touch calibration (adjust if needed)
#define TOUCH_X_MIN 300
#define TOUCH_X_MAX 3800
#define TOUCH_Y_MIN 300
#define TOUCH_Y_MAX 3800

Adafruit_ILI9341 tft = Adafruit_ILI9341(TFT_CS, TFT_DC, TFT_RST);
XPT2046_Touchscreen touch(TOUCH_CS, TOUCH_IRQ);

// --- Script text ---
// Each entry is a line of text (up to CHARS_PER_LINE chars)
const char* script[] = {
  "Welcome to the",
  "Teleprompter!",
  "",
  "This text will",
  "scroll up the",
  "screen.",
  "",
  "Use the button",
  "to pause and",
  "resume.",
  "",
  "Tap left side",
  "to slow down.",
  "",
  "Tap right side",
  "to speed up.",
  "",
  "Add your own",
  "script text by",
  "editing the",
  "script array.",
  "",
  "Good luck with",
  "your recording!",
  "",
  "-- END --",
  "",
  "",
  "",
  "",
};

const int SCRIPT_LINES = sizeof(script) / sizeof(script[0]);
const int VISIBLE_ROWS = SCREEN_H / ROW_H;

// Scrolling state
// scrollPos is in sub-pixel units (pixels * 16) for smooth scrolling
int32_t scrollPos = 0;          // pixels scrolled (top of visible area)
int32_t scrollSpeed = 1;        // pixels per update (1..8)
bool paused = false;

// Button debounce
bool lastBtnState = HIGH;
unsigned long lastBtnTime = 0;
#define DEBOUNCE_MS 50

// Touch debounce
unsigned long lastTouchTime = 0;
#define TOUCH_COOLDOWN_MS 400

// Rendering: track last drawn scroll position to avoid full redraws every frame
int32_t lastDrawnScroll = -9999;

// Total pixel height of script
int totalHeight() {
  return SCRIPT_LINES * ROW_H;
}

// Draw the teleprompter view for a given scroll offset (pixels from top of script)
void drawView(int32_t scrollPx) {
  tft.fillScreen(ILI9341_BLACK);

  // First line index that is (partially) visible
  int firstLine = scrollPx / ROW_H;
  int yOffset = -(scrollPx % ROW_H); // negative offset for partial top line

  for (int i = 0; i < VISIBLE_ROWS + 2; i++) {
    int lineIdx = firstLine + i;
    int y = yOffset + i * ROW_H;
    if (y >= SCREEN_H) break;
    if (lineIdx < 0 || lineIdx >= SCRIPT_LINES) continue;

    // Center text horizontally
    const char* line = script[lineIdx];
    int len = strlen(line);
    int xPos = (SCREEN_W - len * 6 * TEXT_SIZE) / 2;
    if (xPos < 0) xPos = 0;

    tft.setTextSize(TEXT_SIZE);
    tft.setTextColor(ILI9341_WHITE, ILI9341_BLACK);
    tft.setCursor(xPos, y);
    tft.print(line);
  }

  // Draw speed indicator bar at bottom
  tft.fillRect(0, SCREEN_H - 4, (scrollSpeed * SCREEN_W) / 8, 4, ILI9341_GREEN);

  // Draw pause indicator
  if (paused) {
    tft.setTextSize(1);
    tft.setTextColor(ILI9341_YELLOW, ILI9341_BLACK);
    tft.setCursor(2, 2);
    tft.print("PAUSED");
  }
}

// Draw only the speed bar and pause indicator (overlay update)
void drawOverlay() {
  // Clear overlay area
  tft.fillRect(0, 0, 60, 10, ILI9341_BLACK);
  tft.fillRect(0, SCREEN_H - 4, SCREEN_W, 4, ILI9341_BLACK);

  // Speed bar
  tft.fillRect(0, SCREEN_H - 4, (scrollSpeed * SCREEN_W) / 8, 4, ILI9341_GREEN);

  // Pause text
  if (paused) {
    tft.setTextSize(1);
    tft.setTextColor(ILI9341_YELLOW, ILI9341_BLACK);
    tft.setCursor(2, 2);
    tft.print("PAUSED");
  }
}

void setup() {
  Serial.begin(115200);

  // Backlight on
  pinMode(TFT_BL, OUTPUT);
  digitalWrite(TFT_BL, HIGH);

  // Button
  pinMode(BUTTON_PIN, INPUT_PULLUP);

  // TFT init
  tft.begin();
  tft.setRotation(2); // Portrait, connector at top

  // Touch init
  touch.begin();
  touch.setRotation(2);

  // Splash screen
  tft.fillScreen(ILI9341_BLACK);
  tft.setTextSize(2);
  tft.setTextColor(ILI9341_CYAN);
  tft.setCursor(30, 130);
  tft.print("TELEPROMPTER");
  tft.setTextSize(1);
  tft.setTextColor(ILI9341_WHITE);
  tft.setCursor(40, 160);
  tft.print("Press button to start");
  delay(2000);

  // Start paused, position at top with a small margin
  scrollPos = 0;
  paused = true;
  drawView(scrollPos);
  drawOverlay();
}

void loop() {
  unsigned long now = millis();

  // --- Button handling ---
  bool btnState = digitalRead(BUTTON_PIN);
  if (btnState == LOW && lastBtnState == HIGH && (now - lastBtnTime) > DEBOUNCE_MS) {
    paused = !paused;
    lastBtnTime = now;
    drawOverlay();
  }
  lastBtnState = btnState;

  // --- Touch handling ---
  if ((now - lastTouchTime) > TOUCH_COOLDOWN_MS && touch.tirqTouched() && touch.touched()) {
    TS_Point p = touch.getPoint();
    // Map raw touch to screen coordinates
    int tx = map(p.x, TOUCH_X_MIN, TOUCH_X_MAX, 0, SCREEN_W);
    // tx < SCREEN_W/2 = left = slower, tx >= SCREEN_W/2 = right = faster
    if (tx < SCREEN_W / 2) {
      scrollSpeed--;
      if (scrollSpeed < 1) scrollSpeed = 1;
    } else {
      scrollSpeed++;
      if (scrollSpeed > 8) scrollSpeed = 8;
    }
    lastTouchTime = now;
    drawOverlay();
  }

  // --- Scrolling ---
  static unsigned long lastScrollTime = 0;
  // Scroll every 30ms (adjust for smooth motion)
  if (!paused && (now - lastScrollTime) >= 30) {
    lastScrollTime = now;
    scrollPos += scrollSpeed;

    // Clamp: stop at end of script (last line visible)
    int maxScroll = totalHeight() - SCREEN_H;
    if (maxScroll < 0) maxScroll = 0;
    if (scrollPos > maxScroll) {
      scrollPos = maxScroll;
      paused = true; // auto-pause at end
    }

    // Redraw view (full redraw each scroll step)
    drawView(scrollPos);
    drawOverlay();
  }
}

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