LilyGo T-Deck

T-Deck

The LilyGo T-Deck is a development board for the ESP32-S3 module. It features a nice touchscreen display and expansion headers.

The espp::TDeck component provides a singleton hardware abstraction for initializing the touch and display subsystems.

• T-Deck Example
  • How to use example
    • Hardware Required
    • Build and Flash
  • Example Output

API Reference

Header File

• components/t-deck/include/t-deck.hpp

Classes

class TDeck : public espp::BaseComponent

The TDeck class provides an interface to the LilyGo T-Deck ESP32-S3 development board.

The class provides access to the following features:

• Touchpad

• Display

• Keyboard

For more information, see https://github.com/Xinyuan-LilyGO/T-Deck/tree/master and https://github.com/Xinyuan-LilyGO/T-Deck/blob/master/examples/UnitTest/utilities.h

The class is a singleton and can be accessed using the get() method.

Example

  espp::TDeck &tdeck = espp::TDeck::get();
  tdeck.set_log_level(espp::Logger::Verbosity::INFO);

  static auto rotation = LV_DISPLAY_ROTATION_0;

  auto keypress_callback = [&](uint8_t key) {
    logger.info("Key pressed: {}", key);
    if (key == 8) {
      std::lock_guard<std::recursive_mutex> lock(lvgl_mutex);
      clear_circles();
    } else if (key == ' ') {
      std::lock_guard<std::recursive_mutex> lock(lvgl_mutex);
      clear_circles();
      rotation = static_cast<lv_display_rotation_t>((static_cast<int>(rotation) + 1) % 4);
      lv_display_t *disp = _lv_refr_get_disp_refreshing();
      lv_disp_set_rotation(disp, rotation);
    }
  };

  auto touch_callback = [&](const auto &touch) {
    // NOTE: since we're directly using the touchpad data, and not using the
    // TouchpadInput + LVGL, we'll need to ensure the touchpad data is
    // converted into proper screen coordinates instead of simply using the
    // raw values.
    static auto previous_touchpad_data = tdeck.touchpad_convert(touch);
    auto touchpad_data = tdeck.touchpad_convert(touch);
    if (touchpad_data != previous_touchpad_data) {
      logger.info("Touch: {}", touchpad_data);
      previous_touchpad_data = touchpad_data;
      // if there is a touch point, draw a circle
      if (touchpad_data.num_touch_points > 0) {
        std::lock_guard<std::recursive_mutex> lock(lvgl_mutex);
        draw_circle(touchpad_data.x, touchpad_data.y, 10);
      }
    }
  };

  auto trackball_callback = [&](const auto &trackball) {
    logger.debug("Trackball: {}", trackball);
  };

  // initialize the Keyboard
  bool start_task = true;
  if (!tdeck.initialize_keyboard(start_task, keypress_callback)) {
    logger.error("Failed to initialize Keyboard!");
    return;
  }
  // initialize the LCD
  if (!tdeck.initialize_lcd()) {
    logger.error("Failed to initialize LCD!");
    return;
  }
  // set the pixel buffer to be 50 lines high
  static constexpr size_t pixel_buffer_size = tdeck.lcd_width() * 50;
  // initialize the LVGL display for the T-Deck
  if (!tdeck.initialize_display(pixel_buffer_size)) {
    logger.error("Failed to initialize display!");
    return;
  }
  // initialize the touchpad
  if (!tdeck.initialize_touch(touch_callback)) {
    logger.error("Failed to initialize touchpad!");
    return;
  }
  // initialize the trackball
  if (!tdeck.initialize_trackball(trackball_callback)) {
    logger.error("Failed to initialize trackball!");
    return;
  }

  // set the background color to black
  lv_obj_t *bg = lv_obj_create(lv_screen_active());
  lv_obj_set_size(bg, tdeck.lcd_width(), tdeck.lcd_height());
  lv_obj_set_style_bg_color(bg, lv_color_make(0, 0, 0), 0);

  // add text in the center of the screen
  lv_obj_t *label = lv_label_create(lv_screen_active());
  lv_label_set_text(label, "Touch the screen!\nPress the delete key to clear circles.\nPress the "
                           "space key to rotate the display.");
  lv_obj_align(label, LV_ALIGN_CENTER, 0, 0);
  lv_obj_set_style_text_align(label, LV_TEXT_ALIGN_CENTER, 0);

  // add a button in the top left which (when pressed) will rotate the display
  // through 0, 90, 180, 270 degrees
  lv_obj_t *btn = lv_btn_create(lv_screen_active());
  lv_obj_set_size(btn, 50, 50);
  lv_obj_align(btn, LV_ALIGN_TOP_LEFT, 0, 0);
  lv_obj_t *label_btn = lv_label_create(btn);
  lv_label_set_text(label_btn, LV_SYMBOL_REFRESH);
  // center the text in the button
  lv_obj_align(label_btn, LV_ALIGN_CENTER, 0, 0);
  lv_obj_add_event_cb(
      btn,
      [](auto event) {
        std::lock_guard<std::recursive_mutex> lock(lvgl_mutex);
        clear_circles();
        rotation = static_cast<lv_display_rotation_t>((static_cast<int>(rotation) + 1) % 4);
        lv_display_t *disp = _lv_refr_get_disp_refreshing();
        lv_disp_set_rotation(disp, rotation);
      },
      LV_EVENT_PRESSED, nullptr);

  // disable scrolling on the screen (so that it doesn't behave weirdly when
  // rotated and drawing with your finger)
  lv_obj_set_scrollbar_mode(lv_screen_active(), LV_SCROLLBAR_MODE_OFF);
  lv_obj_clear_flag(lv_screen_active(), LV_OBJ_FLAG_SCROLLABLE);

  // start a simple thread to do the lv_task_handler every 16ms
  espp::Task lv_task({.callback = [](std::mutex &m, std::condition_variable &cv) -> bool {
                        {
                          std::lock_guard<std::recursive_mutex> lock(lvgl_mutex);
                          lv_task_handler();
                        }
                        std::unique_lock<std::mutex> lock(m);
                        cv.wait_for(lock, 16ms);
                        return false;
                      },
                      .task_config = {
                          .name = "lv_task",
                      }});
  lv_task.start();

  // set the display brightness to be 75%
  tdeck.brightness(75.0f);

  // now just loop forever
  while (true) {
    std::this_thread::sleep_for(1s);
  }

Note

They keyboard has a backlight, which you can control with the shortcut alt + b. The keyboard backlight is off by default.

Public Types

using Pixel = lv_color16_t

Alias for the pixel type used by the TDeck display.

Public Functions

I2c &internal_i2c()

Get a reference to the internal I2C bus

Note

The internal I2C bus is used for the touchscreen

Returns

A reference to the internal I2C bus

espp::Interrupt &interrupts()

Get a reference to the interrupts

Returns

A reference to the interrupts

void peripheral_power(bool on)

Enable or disable power to the peripherals

Parameters

on – Whether to enable or disable power to the peripherals

bool peripheral_power() const

Get the state of the peripheral power

Returns

true if power is enabled, false otherwise

bool initialize_keyboard(bool start_task = true, const keypress_callback_t &key_cb = nullptr, std::chrono::milliseconds poll_interval = std::chrono::milliseconds(10))

Initialize the keyboard

See also

TKeyboard

See also

keyboard()

Note

The Keyboard has an interrupt pin connected from it (the esp32c3) to the main esp32s3. However, the default firmware on the keyboard (esp32c3) does not use this interrupt pin. Instead, the main esp32s3 must poll the keyboard to get key presses. This is done by the keyboard task. If you update the firmware on the keyboard to use the interrupt pin, you can set start_task to false and wire up the interrupt to the keyboard()->read_key() method.

Parameters

• start_task – Whether to start the keyboard task

• key_cb – The key callback function, called when a key is pressed if not null and the keyboard task is started

• poll_interval – The interval at which to poll the keyboard

Returns

true if the keyboard was successfully initialized, false otherwise

std::shared_ptr<TKeyboard> keyboard() const

Get the keyboard

Note

The keyboard is only available if it was successfully initialized

Returns

A shared pointer to the keyboard

bool initialize_trackball(const trackball_callback_t &trackball_cb = nullptr, int sensitivity = 10)

Initialize the trackball

See also

trackball()

See also

trackball_data()

See also

trackball_read()

See also

set_trackball_sensitivity()

Parameters

• trackball_cb – The trackball callback function, called when the trackball is moved if not null

• sensitivity – The sensitivity of the trackball. The higher the sensitivity, the faster the trackball will move

Returns

true if the trackball was successfully initialized, false otherwise

std::shared_ptr<PointerInput> trackball() const

Get the trackball

See also

initialize_trackball()

See also

trackball_data()

See also

trackball_read()

Note

The trackball is only available if it was successfully initialized

Note

This is the same as the pointer_input() method

Returns

A shared pointer to the trackball

void set_trackball_sensitivity(int sensitivity)

Set the trackball sensitivity

Note

The sensitivity can be negative, which will invert the direction of the trackball

Parameters

sensitivity – The sensitivity of the trackball. The higher the sensitivity, the faster the trackball will move

std::shared_ptr<PointerInput> pointer_input() const

Get the pointer input for the trackball

Returns

A shared pointer to the pointer input for the trackball

espp::PointerData trackball_data() const

Get the most recent trackball data

Returns

The trackball data

void trackball_read(int &x, int &y, bool &left_pressed, bool &right_pressed)

Get the most recent trackball data

Note

This method is a convenience method for integrating with LVGL, the data it returns is identical to the data returned by the trackball_data() method

Parameters

• x – The x coordinate

• y – The y coordinate

• left_pressed – Whether the left button is pressed

• right_pressed – Whether the right button is pressed

bool initialize_touch(const touch_callback_t &touch_cb = nullptr)

Initialize the touchpad

Note

This will configure the touchpad interrupt pin which will automatically call the touch callback function when the touchpad is touched

Warning

This method should be called after the display has been initialized if you want the touchpad to be recognized and used with LVGL and its objects.

Parameters

touch_cb – The touch callback function, called when the touchpad is touched if not null

Returns

true if the touchpad was successfully initialized, false otherwise

std::shared_ptr<TouchpadInput> touchpad_input() const

Get the touchpad input

Returns

A shared pointer to the touchpad input

espp::TouchpadData touchpad_data() const

Get the most recent touchpad data

Returns

The touchpad data

void touchpad_read(uint8_t *num_touch_points, uint16_t *x, uint16_t *y, uint8_t *btn_state)

Get the most recent touchpad data

See also

touchpad_data()

Note

This method is a convenience method for integrating with LVGL, the data it returns is identical to the data returned by the touchpad_data() method

Parameters

• num_touch_points – The number of touch points

• x – The x coordinate

• y – The y coordinate

• btn_state – The button state (0 = button released, 1 = button pressed)

espp::TouchpadData touchpad_convert(const espp::TouchpadData &data) const

Convert touchpad data from raw reading to display coordinates

Note

Uses the touch_invert_x and touch_invert_y settings to determine if the x and y coordinates should be inverted

Parameters

data – The touchpad data to convert

Returns

The converted touchpad data

bool initialize_lcd()

Initialize the LCD (low level display driver)

Returns

true if the LCD was successfully initialized, false otherwise

bool initialize_display (size_t pixel_buffer_size, const espp::Task::BaseConfig &task_config={.name="Display",.stack_size_bytes=4096,.priority=10,.core_id=0}, int update_period_ms=16)

Initialize the display (lvgl display driver)

Note

This will also allocate two full frame buffers in the SPIRAM

Parameters

• pixel_buffer_size – The size of the pixel buffer

• task_config – The task configuration for the display task

• update_period_ms – The update period of the display task

Returns

true if the display was successfully initialized, false otherwise

std::shared_ptr<Display<Pixel>> display() const

Get a shared pointer to the display

Returns

A shared pointer to the display

void brightness(float brightness)

Set the brightness of the backlight

Parameters

brightness – The brightness of the backlight as a percentage (0 - 100)

float brightness() const

Get the brightness of the backlight

Returns

The brightness of the backlight as a percentage (0 - 100)

Pixel *vram0() const

Get the VRAM 0 pointer (DMA memory used by LVGL)

Note

This is the memory used by LVGL for rendering

Note

This is null unless initialize_display() has been called

Returns

The VRAM 0 pointer

Pixel *vram1() const

Get the VRAM 1 pointer (DMA memory used by LVGL)

Note

This is the memory used by LVGL for rendering

Note

This is null unless initialize_display() has been called

Returns

The VRAM 1 pointer

uint8_t *frame_buffer0() const

Get the frame buffer 0 pointer

Note

This memory is designed to be used by the application developer and is provided as a convenience. It is not used by the display driver.

Note

This is null unless initialize_display() has been called

Returns

The frame buffer 0 pointer

uint8_t *frame_buffer1() const

Get the frame buffer 1 pointer

Note

This memory is designed to be used by the application developer and is provided as a convenience. It is not used by the display driver.

Note

This is null unless initialize_display() has been called

Returns

The frame buffer 1 pointer

void write_lcd(const uint8_t *data, size_t length, uint32_t user_data)

Write data to the LCD

Note

This method is designed to be used by the display driver

Note

This method queues the data to be written to the LCD, only blocking if there is an ongoing SPI transaction

Parameters

• data – The data to write

• length – The length of the data

• user_data – User data to pass to the spi transaction callback

void write_lcd_frame(const uint16_t x, const uint16_t y, const uint16_t width, const uint16_t height, uint8_t *data)

Write a frame to the LCD

Note

This method queues the data to be written to the LCD, only blocking if there is an ongoing SPI transaction

Parameters

• x – The x coordinate

• y – The y coordinate

• width – The width of the frame, in pixels

• height – The height of the frame, in pixels

• data – The data to write

void write_lcd_lines(int xs, int ys, int xe, int ye, const uint8_t *data, uint32_t user_data)

Write lines to the LCD

Note

This method queues the data to be written to the LCD, only blocking if there is an ongoing SPI transaction

Parameters

• xs – The x start coordinate

• ys – The y start coordinate

• xe – The x end coordinate

• ye – The y end coordinate

• data – The data to write

• user_data – User data to pass to the spi transaction callback

inline const std::string &get_name() const

Get the name of the component

Note

This is the tag of the logger

Returns

A const reference to the name of the component

inline void set_log_tag(const std::string_view &tag)

Set the tag for the logger

Parameters

tag – The tag to use for the logger

inline espp::Logger::Verbosity get_log_level() const

Get the log level for the logger

See also

Logger::Verbosity

See also

Logger::set_verbosity

Returns

The verbosity level of the logger

inline void set_log_level(espp::Logger::Verbosity level)

Set the log level for the logger

See also

Logger::Verbosity

See also

Logger::set_verbosity

Parameters

level – The verbosity level to use for the logger

inline void set_log_verbosity(espp::Logger::Verbosity level)

Set the log verbosity for the logger

See also

set_log_level

See also

Logger::Verbosity

See also

Logger::set_verbosity

Note

This is a convenience method that calls set_log_level

Parameters

level – The verbosity level to use for the logger

inline espp::Logger::Verbosity get_log_verbosity() const

Get the log verbosity for the logger

See also

get_log_level

See also

Logger::Verbosity

See also

Logger::get_verbosity

Note

This is a convenience method that calls get_log_level

Returns

The verbosity level of the logger

inline void set_log_rate_limit(std::chrono::duration<float> rate_limit)

Set the rate limit for the logger

See also

Logger::set_rate_limit

Note

Only calls to the logger that have _rate_limit suffix will be rate limited

Parameters

rate_limit – The rate limit to use for the logger

Public Static Functions

static inline TDeck &get()

Access the singleton instance of the TDeck class.

Returns

Reference to the singleton instance of the TDeck class

static inline constexpr auto peripheral_power_pin()

Get the GPIO pin for the peripheral power

Note

This pin is used to enable/disable power to the peripherals, such as the keyboard, screen, etc.

Returns

The GPIO pin for the peripheral power

static inline constexpr auto keyboard_interrupt()

Get the GPIO pin for the keyboard interrupt

Note

This pin is used to detect when a key is pressed on the keyboard and is connected to the main esp32s3, however the default firmware on the keyboard does not use this pin

Returns

The GPIO pin for the keyboard interrupt

static inline constexpr auto trackball_up_gpio()

Get the GPIO pin for the trackball up button

Returns

The GPIO pin for the trackball up button

static inline constexpr auto trackball_down_gpio()

Get the GPIO pin for the trackball down button

Returns

The GPIO pin for the trackball down button

static inline constexpr auto trackball_left_gpio()

Get the GPIO pin for the trackball left button

Returns

The GPIO pin for the trackball left button

static inline constexpr auto trackball_right_gpio()

Get the GPIO pin for the trackball right button

Returns

The GPIO pin for the trackball right button

static inline constexpr auto trackball_btn_gpio()

Get the GPIO pin for the trackball button

Returns

The GPIO pin for the trackball button

static inline constexpr size_t lcd_width()

Get the width of the LCD in pixels

Returns

The width of the LCD in pixels

static inline constexpr size_t lcd_height()

Get the height of the LCD in pixels

Returns

The height of the LCD in pixels

static inline constexpr auto get_lcd_dc_gpio()

Get the GPIO pin for the LCD data/command signal

Returns

The GPIO pin for the LCD data/command signal