Rename project.

+ Refactor most classes to header only.

esp/cpp/07_lcd-panel-i2c/CMakeLists.txt

@@ -7,9 +7,9 @@ cmake_minimum_required(VERSION 3.26)
 include($ENV{IDF_PATH}/tools/cmake/project.cmake)
 
 project(
-    #[[NAME]]   lcd-panel
+    #[[NAME]]   lcd-panel-i2c
     VERSION     0.1
-    DESCRIPTION "Example of using the SSD1306 LCD display with ESP-IDF and LVGL"
+    DESCRIPTION "Using the SSD1306 LCD display with ESP-IDF and LVGL over I2C"
     LANGUAGES   CXX
 )
 # For writing pure cmake components, see the documentation

esp/cpp/07_lcd-panel-i2c/README.md

@@ -0,0 +1,29 @@
+# 07_lcd-panel-i2c
+
+Using the ESP IDF for drawing to a LCD screen over I2C.
+
+For instructions on setting up the ESP-IDF see [04_-esp-idf-arduino](./../04_esp-idf-arduino)
+
+[ESP IDF - I2C](https://docs.espressif.com/projects/esp-idf/en/v5.3.2/esp32/api-reference/peripherals/i2c.html)
+
+[ESP IDF - LCD](https://docs.espressif.com/projects/esp-idf/en/v5.3.2/esp32/api-reference/peripherals/lcd/index.html)
+
+[ESP IDF - FreeRTOS](https://docs.espressif.com/projects/esp-idf/en/v5.3.2/esp32/api-reference/system/freertos.html)
+
+![schematic](./schematic.png)
+
+Temperature and humidity sensor served on a web page within the local network.
+
+![example](./example.gif)
+
+To build this example run the following commands.
+
+```bash
+source ~/path/to/esp-idf/export.sh
+
+mkdir build
+cd build
+cmake ..
+make -j $(nproc)
+make flash
+```

esp/cpp/07_lcd-panel-i2c/main/CMakeLists.txt

@@ -0,0 +1 @@
+idf_component_register(SRC_DIRS . INCLUDE_DIRS .)

esp/cpp/07_lcd-panel-i2c/main/display.cpp

@@ -1,72 +1,40 @@
 
+#include <esp_timer.h>
+
+#include <lv_init.h>
+
+#include <mutex>
+
 #include "display.h"
-#include "ssd1306.h"
 
-#include "widgets/label/lv_label.h"
-#include <esp_log.h>
-#include <esp_lcd_panel_ops.h>
-#include <esp_heap_caps.h>
-#include <esp_lcd_panel_io.h>
-#include <esp_timer.h>
-#include <lv_init.h>
-#include <display/lv_display.h>
-#include <driver/i2c_master.h>
-#include <mutex>
+// TODO: Remove this dependency by relocating SSD1306::oledb_buffer_
+#include "ssd1306.h"
 
 // LVGL library is not thread-safe, this example calls LVGL APIs from tasks.
 // We must use a mutex to protect it.
-_lock_t ScopedLock::lock_;
+_lock_t Display::ScopedLock::lv_lock_;
 
-Display::Display(IPanelDevice *device) :
-    panel_(device)
+// Static TimeKeeper for managing ESP timers across all displays.
+TimeKeeper Display::timers_;
+
+Display::Display(IPanelDevice &device) :
+    panel_(device),
+    lv_buf_(nullptr)
 {
   if (!lv_is_initialized()) {
     ESP_LOGI(TAG, "Initialize LVGL");
     lv_init();
   }
 
-  // Create a lvgl display.
+  ESP_LOGI(TAG, "Creating LVGL display");
   lv_display_ = panel_.device_->create_display();
   // associate the i2c panel handle to the display
   lv_display_set_user_data(lv_display_, panel_.esp_panel_);
 
-  // Create draw buffer.
-  ESP_LOGI(TAG, "Allocate separate LVGL draw buffers");
-  lv_buf_ = heap_caps_calloc(1, panel_.device_->lv_buf_size_,
-                             MALLOC_CAP_INTERNAL | MALLOC_CAP_8BIT);
-  assert(lv_buf_);
+  register_draw_buffer();
+  register_lvgl_tick_timer();
 
-  // LVGL9 suooprt new monochromatic format.
-  lv_display_set_color_format(lv_display_, LV_COLOR_FORMAT_I1);
-  // Initialize LVGL draw buffers.
-  lv_display_set_buffers(lv_display_, lv_buf_, nullptr,
-                         panel_.device_->lv_buf_size_,
-                         LV_DISPLAY_RENDER_MODE_FULL);
-  lv_display_set_rotation(lv_display_, LV_DISPLAY_ROTATION_0);
-  // Set callback which can copy the rendered image to an area of the display.
-  lv_display_set_flush_cb(lv_display_, Display::lvgl_flush_cb);
-
-  ESP_LOGI(TAG, "Register io panel callback for LVGL flush ready notification");
-  const esp_lcd_panel_io_callbacks_t cbs = {
-      .on_color_trans_done = Display::lvgl_flush_ready,
-  };
-  /* Register done callback */
-  ESP_ERROR_CHECK(
-      esp_lcd_panel_io_register_event_callbacks(panel_.io_handle_, &cbs,
-                                                lv_display_));
-
-  // TODO: What is this
-  ESP_LOGI(TAG, "Use esp_timer as LVGL tick timer");
-  const esp_timer_create_args_t lvgl_tick_timer_args = {
-      .callback = &Display::lvgl_increase_tick,
-      .name = "lvgl_tick"
-  };
-  esp_timer_handle_t lvgl_tick_timer = nullptr;
-  ESP_ERROR_CHECK(esp_timer_create(&lvgl_tick_timer_args, &lvgl_tick_timer));
-  ESP_ERROR_CHECK(esp_timer_start_periodic(lvgl_tick_timer,
-                                           LVGL_TICK_PERIOD_MS * 1000));
-
-  ESP_LOGI(TAG, "Create LVGL task");
+  ESP_LOGI(TAG, "Create LVGL FreeRTOS task");
   xTaskCreate(Display::lvgl_port_task, "LVGL", LVGL_TASK_STACK_SIZE,
               nullptr, LVGL_TASK_PRIORITY, nullptr);
 }
@@ -81,10 +49,14 @@ void Display::set_text(const char *text,
 
   ESP_LOGI(TAG, "Display LVGL Scroll Text");
   lv_obj_t *scr = lv_display_get_screen_active(lv_display_);
-  objects_[name] = lv_label_create(scr);
+
+  // Create the label if it's `name` doesn't already exist in the map keys.
+  if (!lv_objects_.count(name)) {
+    lv_objects_[name] = lv_label_create(scr);
+  }
+  auto obj = lv_objects_[name];
 
   // Circular scroll.
-  auto obj = objects_[name];
   lv_label_set_long_mode(obj, long_mode);
   lv_label_set_text(obj, text);
 
@@ -94,9 +66,9 @@ void Display::set_text(const char *text,
   lv_obj_align(obj, align, 0, 0);
 }
 
-bool Display::lvgl_flush_ready(esp_lcd_panel_io_handle_t,
-                               esp_lcd_panel_io_event_data_t *,
-                               void *user_ctx)
+bool Display::lvgl_flush_ready_cb(esp_lcd_panel_io_handle_t,
+                                  esp_lcd_panel_io_event_data_t *,
+                                  void *user_ctx)
 {
   auto *disp = (lv_display_t *) user_ctx;
   lv_display_flush_ready(disp);
@@ -104,7 +76,7 @@ bool Display::lvgl_flush_ready(esp_lcd_panel_io_handle_t,
 }
 
 void Display::lvgl_flush_cb(lv_display_t *display, const lv_area_t *area,
-                            uint8_t *px_map)
+                            uint8_t *px_map) // NOLINT(*-non-const-parameter)
 {
   auto panel_handle =
       (esp_lcd_panel_handle_t) lv_display_get_user_data(display);
@@ -148,7 +120,7 @@ void Display::lvgl_flush_cb(lv_display_t *display, const lv_area_t *area,
                                 SSD1306::oled_buffer_));
 }
 
-void Display::lvgl_increase_tick(void *)
+void Display::lvgl_increase_tick_cb(void *)
 {
   // Tell LVGL how many milliseconds has elapsed
   lv_tick_inc(LVGL_TICK_PERIOD_MS);
@@ -158,55 +130,47 @@ void Display::lvgl_increase_tick(void *)
 {
   ESP_LOGI(TAG, "Starting LVGL task");
   for (uint32_t time_till_next_ms = 0; true;) {
-    _lock_acquire(&ScopedLock::lock_);
+    _lock_acquire(&ScopedLock::lv_lock_);
     time_till_next_ms = lv_timer_handler();
-    _lock_release(&ScopedLock::lock_);
+    _lock_release(&ScopedLock::lv_lock_);
     usleep(1000 * time_till_next_ms);
   }
 }
 
-I2C::I2C(gpio_num_t sda, gpio_num_t scl) :
-    i2c_bus_(nullptr),
-    bus_config_(
-        (i2c_master_bus_config_t) {
-            .i2c_port = I2C_BUS_PORT,
-            .sda_io_num = sda,
-            .scl_io_num = scl,
-            .clk_source = I2C_CLK_SRC_DEFAULT,
-            .glitch_ignore_cnt = 7,
-            .flags {
-                .enable_internal_pullup = true,
-            },
-        }
-    )
+void Display::register_draw_buffer()
 {
-  ESP_LOGI(TAG, "Initialize I2C bus");
-  ESP_ERROR_CHECK(i2c_new_master_bus(&bus_config_, &i2c_bus_));
+  // Create draw buffer.
+  ESP_LOGI(TAG, "Allocate separate LVGL draw buffers");
+  lv_buf_ = heap_caps_calloc(1, panel_.device_->lv_buf_size_,
+                             MALLOC_CAP_INTERNAL | MALLOC_CAP_8BIT);
+  assert(lv_buf_);
+
+  ESP_LOGI(TAG, "Set LVGL draw buffers");
+  // Color format must be set first, LVGL9 suooprt new monochromatic format.
+  lv_display_set_color_format(lv_display_, LV_COLOR_FORMAT_I1);
+  lv_display_set_buffers(lv_display_, lv_buf_, nullptr,
+                         panel_.device_->lv_buf_size_,
+                         LV_DISPLAY_RENDER_MODE_FULL);
+  lv_display_set_rotation(lv_display_, LV_DISPLAY_ROTATION_0);
+
+  ESP_LOGI(TAG, "Set LVGL callback for flushing to the display");
+  lv_display_set_flush_cb(lv_display_, Display::lvgl_flush_cb);
+
+  ESP_LOGI(TAG, "Register io panel callback for LVGL flush ready notification");
+  const esp_lcd_panel_io_callbacks_t cbs = {
+      .on_color_trans_done = Display::lvgl_flush_ready_cb,
+  };
+  ESP_ERROR_CHECK(
+      esp_lcd_panel_io_register_event_callbacks(panel_.esp_io_, &cbs,
+                                                lv_display_));
 }
 
-Panel::Panel(IPanelDevice *device) :
-    device_(device),
-    io_handle_(nullptr),
-    esp_panel_(nullptr),
-    // According to SSD1306 datasheet
-    panel_config_(
-        (esp_lcd_panel_dev_config_t) {
-            .reset_gpio_num = device_->reset_gpio_num_,
-            .bits_per_pixel = 1,
-            // .vendor_config should be set in IPanelDevice::init_panel override
-        }
-    )
+void Display::register_lvgl_tick_timer()
 {
-  ESP_LOGI(TAG, "Install panel IO");
-  ESP_ERROR_CHECK(esp_lcd_new_panel_io_i2c(
-      device_->i2c_bus_, &device_->io_config_, &io_handle_));
-
-  device_->create_panel(panel_config_, io_handle_, esp_panel_);
-
-  ESP_LOGI(TAG, "Resetting panel display");
-  ESP_ERROR_CHECK(esp_lcd_panel_reset(esp_panel_));
-  ESP_LOGI(TAG, "Initializing panel display");
-  ESP_ERROR_CHECK(esp_lcd_panel_init(esp_panel_));
-  ESP_LOGI(TAG, "Turning on panel display");
-  ESP_ERROR_CHECK(esp_lcd_panel_disp_on_off(esp_panel_, true));
+  ESP_LOGI(TAG, "Use esp_timer to increase LVGL tick");
+  const esp_timer_create_args_t esp_timer_args = {
+      .callback = &Display::lvgl_increase_tick_cb,
+      .name = "lvgl_tick"
+  };
+  timers_.start_new_timer_periodic(esp_timer_args, LVGL_TICK_PERIOD_MS * 1000);
 }

esp/cpp/07_lcd-panel-i2c/main/display.h

@@ -0,0 +1,139 @@
+#ifndef DISPLAY_H
+#define DISPLAY_H
+
+
+#include <widgets/label/lv_label.h>
+
+#include <unordered_map>
+
+#include "time_keeper.h"
+#include "panel.h"
+
+#define LVGL_TICK_PERIOD_MS    5
+#define LVGL_TASK_STACK_SIZE   (4 * 1024)
+#define LVGL_TASK_PRIORITY     2
+
+class Display {
+public:
+  //
+  // CONSTRUCTORS
+
+  Display(const Display &) = delete;
+
+  Display(Display &) = delete;
+
+  Display &operator=(Display &) = delete;
+
+  /**
+   * Construct a new Display using an IPanelDevice.
+   *
+   * @param device An object that implements the IPanelDevice interface.
+   */
+  explicit Display(IPanelDevice &device);
+
+  ~Display() = default;
+
+  //
+  // GETTERS
+
+  /**
+   * Getter for accessing LVGL display handle.
+   *
+   * @sa ScopedLock for calling custom LVGL API's not implemented by Display.
+   */
+  [[nodiscard]] inline const lv_display_t *get() const { return lv_display_; }
+
+  /**
+   * Getter for accessing LVGL display handle.
+   *
+   * @sa ScopedLock for calling custom LVGL API's not implemented by Display.
+   */
+  [[nodiscard]] inline lv_display_t *get() { return lv_display_; }
+
+  /// Dereference operator for accessing LVGL display handle.
+  [[nodiscard]] inline const lv_display_t *operator*() const { return get(); }
+
+  /// Dereference operator for accessing LVGL display handle.
+  [[nodiscard]] inline lv_display_t *operator*() { return get(); }
+
+  //
+  // LVGL OPERATIONS
+
+  /**
+   * Create a LVGL label with some given text on the current display.
+   * The name of the object can be reused to change text on this label later.
+   *
+   * @param text Text to write to the display.
+   * @param name Name for the LVGL label object associated with this text.
+   * @param long_mode LVGL long mode for text wider than the current display.
+   * @param align LVGL alignment to use for placing the label on the display.
+   */
+  void set_text(const char *text,
+                const char *name,
+                lv_label_long_mode_t long_mode = LV_LABEL_LONG_SCROLL_CIRCULAR,
+                lv_align_t align = LV_ALIGN_TOP_MID);
+
+  //
+  // TYPE DEFINITIONS
+
+  /**
+   * Obtains LVGL API mutex lock for the duration of local scope.
+   *
+   * LVGL library is not thread-safe, this example calls LVGL APIs from tasks.
+   */
+  struct ScopedLock {
+    explicit ScopedLock() { _lock_acquire(&lv_lock_); }
+
+    ~ScopedLock() { _lock_release(&lv_lock_); }
+
+    /// Mutex used to protect LVGL API calls.
+    static _lock_t lv_lock_;
+  };
+
+  //
+  // PUBLIC STATIC MEMBERS
+
+  /// Public static TimeKeeper for managing ESP timers across all displays.
+  static TimeKeeper timers_;
+
+private:
+  /// Registers LVGL draw buffers for this display.
+  void register_draw_buffer();
+
+  /// Registers LVGL ticker timer callback for rendering this display.
+  static void register_lvgl_tick_timer();
+
+  static bool lvgl_flush_ready_cb(esp_lcd_panel_io_handle_t panel,
+                                  esp_lcd_panel_io_event_data_t *data,
+                                  void *user_ctx);
+
+  static void lvgl_flush_cb(lv_display_t *display,
+                            const lv_area_t *area,
+                            uint8_t *px_map);
+
+  static void lvgl_increase_tick_cb(void *arg);
+
+  [[noreturn]] static void lvgl_port_task(void *arg);
+
+  //
+  // PRIVATE MEMBERS
+
+  /// Panel associated with this Display.
+  Panel panel_;
+
+  /// LVGL display handle.
+  lv_display_t *lv_display_;
+
+  /// LVGL draw buffer associated with this Display's lv_display_t.
+  void *lv_buf_;
+
+  /**
+   * LVGL object handles stored in the LVGL screen associated with this Display.
+   *
+   * @sa Display::set_text
+   * @sa lv_display_get_screen_active
+   */
+  std::unordered_map<const char *, lv_obj_t *> lv_objects_;
+};
+
+#endif // DISPLAY_H

esp/cpp/07_lcd-panel-i2c/main/i2c.h

@@ -0,0 +1,42 @@
+#ifndef I2C_H
+#define I2C_H
+
+#define I2C_BUS_PORT  0
+
+#include <driver/i2c_master.h>
+
+static const char *TAG = "lcd-panel";
+
+struct I2C {
+  I2C(gpio_num_t sda, gpio_num_t scl, int rst = -1) :
+      esp_i2c_bus_(nullptr),
+      rst_num_(rst),
+      esp_bus_config_(
+          (i2c_master_bus_config_t) {
+              .i2c_port = I2C_BUS_PORT,
+              .sda_io_num = sda,
+              .scl_io_num = scl,
+              .clk_source = I2C_CLK_SRC_DEFAULT,
+              .glitch_ignore_cnt = 7,
+              .flags {
+                  .enable_internal_pullup = true,
+              },
+          }
+      )
+  {
+    ESP_LOGI(TAG, "Initializing new master I2C bus");
+    ESP_ERROR_CHECK(i2c_new_master_bus(&esp_bus_config_, &esp_i2c_bus_));
+  }
+
+  ~I2C() = default;
+
+  // TODO: Can you use the I2C get_master_bus API in a static method?
+  i2c_master_bus_handle_t esp_i2c_bus_;
+
+  int rst_num_;
+
+private:
+  i2c_master_bus_config_t esp_bus_config_;
+};
+
+#endif //I2C_H

esp/cpp/07_lcd-panel-i2c/main/main.cpp

@@ -4,22 +4,25 @@
 // Pin may vary based on your schematic.
 #define PIN_SDA                GPIO_NUM_21
 #define PIN_SCL                GPIO_NUM_22
-#define PIN_RST                -1
+#define PIN_RST                (-1)
 
-// TODO: Can this be static since there can only be one initialization?
-// TODO: Store RST in I2C and retrieve within SSD instead of the #define
-I2C i2c(PIN_SDA, PIN_SCL);
+I2C i2c(PIN_SDA, PIN_SCL, PIN_RST);
 
 void setup()
 {
-  SSD1306 ssd1306(i2c.i2c_bus_);
-  Display d(&ssd1306);
+  SSD1306 ssd1306(i2c);
+  Display d(ssd1306);
 
   d.set_text("Test test 12345678910",
              "test-text1",
              LV_LABEL_LONG_SCROLL,
              LV_ALIGN_CENTER);
 
+  d.set_text("Test test changing text",
+             "test-text1",
+             LV_LABEL_LONG_SCROLL,
+             LV_ALIGN_CENTER);
+
   d.set_text("Hello hello hello hello hello hello hello hello!", "test-text2");
 
   d.set_text("A random sentence with no meaning at all.",

esp/cpp/07_lcd-panel-i2c/main/panel.h

@@ -0,0 +1,44 @@
+#ifndef PANEL_H
+#define PANEL_H
+
+#include "panel_device.h"
+
+class Panel {
+public:
+  explicit Panel(IPanelDevice &device) :
+      device_(&device),
+      esp_io_(nullptr),
+      esp_panel_(nullptr),
+      esp_panel_config_(
+          (esp_lcd_panel_dev_config_t) {
+              .reset_gpio_num = device_->rst_num_,
+              .bits_per_pixel = 1,
+              .vendor_config = device_->vendor_config(),
+          }
+      )
+  {
+    esp_io_ = device_->create_io_handle();
+
+    device_->create_panel(esp_panel_config_, esp_io_, esp_panel_);
+
+    ESP_LOGI(TAG, "Resetting panel display");
+    ESP_ERROR_CHECK(esp_lcd_panel_reset(esp_panel_));
+    ESP_LOGI(TAG, "Initializing panel display");
+    ESP_ERROR_CHECK(esp_lcd_panel_init(esp_panel_));
+    ESP_LOGI(TAG, "Turning on panel display");
+    ESP_ERROR_CHECK(esp_lcd_panel_disp_on_off(esp_panel_, true));
+  }
+
+  ~Panel() = default;
+
+  IPanelDevice *device_;
+
+  esp_lcd_panel_io_handle_t esp_io_;
+
+  esp_lcd_panel_handle_t esp_panel_;
+
+private:
+  esp_lcd_panel_dev_config_t esp_panel_config_;
+};
+
+#endif //PANEL_H

esp/cpp/07_lcd-panel-i2c/main/panel_device.h

@@ -3,24 +3,35 @@
 
 #include <esp_lcd_panel_dev.h>
 #include <esp_lcd_panel_ops.h>
-#include <esp_lcd_panel_ssd1306.h>
-#include <driver/i2c_types.h>
 #include <esp_lcd_panel_io.h>
 #include <esp_log.h>
-#include "display/lv_display.h"
+
+#include <display/lv_display.h>
+
+#include "i2c.h"
 
 #define LVGL_PALETTE_SIZE      8
 
-static const char *TAG = "lcd-panel";
-
 class IPanelDevice {
 public:
-  explicit IPanelDevice(i2c_master_bus_handle_t i2c,
-                        int reset_gpio_num,
-                        esp_lcd_panel_io_i2c_config_t io_config) :
-      reset_gpio_num_(reset_gpio_num),
-      i2c_bus_(i2c),
-      io_config_(io_config) { }
+  explicit IPanelDevice(I2C &i2c,
+                        esp_lcd_panel_io_i2c_config_t config,
+                        int width,
+                        int height) :
+      IPanelDevice(i2c, config, width, height,
+                   width * height / 8 + LVGL_PALETTE_SIZE) { }
+
+  explicit IPanelDevice(I2C &i2c,
+                        esp_lcd_panel_io_i2c_config_t io_config,
+                        int width,
+                        int height,
+                        size_t draw_buf_size) :
+      width_(width),
+      height_(height),
+      rst_num_(i2c.rst_num_),
+      lv_buf_size_(draw_buf_size),
+      esp_i2c_bus_(i2c.esp_i2c_bus_),
+      esp_io_config_(io_config) { }
 
   virtual ~IPanelDevice() = default;
 
@@ -31,6 +42,15 @@ public:
     return display;
   }
 
+  [[nodiscard]] esp_lcd_panel_io_handle_t create_io_handle()
+  {
+    ESP_LOGI(TAG, "Creating panel IO handle");
+    esp_lcd_panel_io_handle_t handle = nullptr;
+    ESP_ERROR_CHECK(
+        esp_lcd_new_panel_io_i2c(esp_i2c_bus_, &esp_io_config_, &handle));
+    return handle;
+  }
+
   void create_panel(esp_lcd_panel_dev_config_t &config,
                     esp_lcd_panel_io_handle_t io,
                     esp_lcd_panel_handle_t &panel)
@@ -45,16 +65,20 @@ public:
     init_panel(config, io, panel);
   }
 
+  virtual void *vendor_config() = 0;
+
   int32_t width_;
+
   int32_t height_;
-  int reset_gpio_num_;
+
+  int rst_num_;
 
   // LVGL reserves 2x4 bytes in the buffer to be used as a palette.
   size_t lv_buf_size_;
-  // TODO: Can we use a static accessor in I2C instead?
-  i2c_master_bus_handle_t i2c_bus_;
 
-  esp_lcd_panel_io_i2c_config_t io_config_;
+  i2c_master_bus_handle_t esp_i2c_bus_;
+
+  esp_lcd_panel_io_i2c_config_t esp_io_config_;
 
 private:
   virtual void init_panel(esp_lcd_panel_dev_config_t &config,

esp/cpp/07_lcd-panel-i2c/main/ssd1306.cpp

@@ -0,0 +1,6 @@
+
+#include "ssd1306.h"
+
+// To use LV_COLOR_FORMAT_I1 we need an extra buffer to hold the converted data.
+// TODO: Remove this and SSD1306 can be header only.
+uint8_t SSD1306::oled_buffer_[LCD_H_RES * LCD_V_RES / 8];

esp/cpp/07_lcd-panel-i2c/main/ssd1306.h

@@ -0,0 +1,83 @@
+/*
+ * https://docs.espressif.com/projects/esp-idf/en/v5.3.2/esp32/api-reference/peripherals/lcd/index.html#functional-overview
+ *
+ * Implementing the interface draw to an LCD using various interface modes.
+ * I2C interface mode is SSD1306
+ * SPI interface mode is ST7789
+ * I80 interface mode is NT35510 or ST7789
+ *
+ * Actually, I think any driver can be used with any interface mode
+ * Along with additional third party drivers via the component manager
+ * https://github.com/espressif/esp-idf/tree/0d6099ec533c4b647fb7a7b0b8942bc7aeb82f90/examples/peripherals/lcd/spi_lcd_touch#spi-lcd-and-touch-panel-example
+ */
+
+#ifndef SSD1306_H
+#define SSD1306_H
+
+#include <esp_lcd_panel_ssd1306.h>
+
+#include "panel_device.h"
+
+// According to specific display hardware.
+// https://www.digikey.com/en/products/detail/winstar-display/WEA012864DWPP3N00003/20533255
+#define SCREEN_WIDTH           128  // OLED display width, in pixels.
+#define SCREEN_HEIGHT          64  // OLED display height, in pixels.
+
+// According to SSD1306 datasheet.
+// https://cdn-shop.adafruit.com/datasheets/SSD1306.pdf
+#define LCD_H_RES              128
+#define LCD_V_RES              64
+#define I2C_HW_ADDR            0x3C
+#define LCD_PIXEL_CLOCK_HZ     (400 * 1000)
+// Bit number used to represent command and parameter
+#define LCD_CMD_BITS           8
+#define LCD_PARAM_BITS         8
+
+class SSD1306 final : public IPanelDevice {
+public:
+  // Constructors allow overriding ssd1306 config.
+  explicit SSD1306(I2C &i2c) :
+      SSD1306(i2c, {.height = SCREEN_HEIGHT}) { }
+
+  SSD1306(I2C &i2c,
+          esp_lcd_panel_ssd1306_config_t config,
+          int width = SCREEN_WIDTH,
+          int height = SCREEN_HEIGHT
+  ) :
+      IPanelDevice(i2c,
+                   (esp_lcd_panel_io_i2c_config_t) {
+                       .dev_addr = I2C_HW_ADDR,
+                       .control_phase_bytes = 1,
+                       .dc_bit_offset = 6,
+                       .lcd_cmd_bits = LCD_CMD_BITS,
+                       .lcd_param_bits = LCD_PARAM_BITS,
+                       .scl_speed_hz = LCD_PIXEL_CLOCK_HZ,
+                   },
+                   width,
+                   height
+      ),
+      ssd1306_config_(config) { }
+
+  ~SSD1306() final = default;
+
+  void *vendor_config() override
+  {
+    return &ssd1306_config_;
+  }
+
+  // The configuration structure specific to the SSD1306.
+  esp_lcd_panel_ssd1306_config_t ssd1306_config_;
+
+  // For LV_COLOR_FORMAT_I1 we need an extra buffer to hold the converted data.
+  static uint8_t oled_buffer_[LCD_H_RES * LCD_V_RES / 8];
+
+private:
+  void init_panel(esp_lcd_panel_dev_config_t &config,
+                  esp_lcd_panel_io_handle_t io,
+                  esp_lcd_panel_handle_t &panel) override
+  {
+    ESP_ERROR_CHECK(esp_lcd_new_panel_ssd1306(io, &config, &panel));
+  }
+};
+
+#endif // SSD1306_H

esp/cpp/07_lcd-panel-i2c/main/time_keeper.h

@@ -0,0 +1,131 @@
+
+#ifndef TIME_KEEPER_H
+#define TIME_KEEPER_H
+
+#include <esp_log.h>
+#include <esp_timer.h>
+
+#include "i2c.h"
+
+/**
+ * Stores arguments and ESP timer handle for a Timer.
+ * In general Timers should be used via the TimeKeeper interface only.
+ *
+ * Timers cannot be copied, and are only created by a TimeKeeper instance.
+ * The public way to access a Timer is by obtaining a TimerHandle (Timer *).
+ * The TimeKeeper can delete existing Timers, calling it's destructor.
+ * The ESP timer will be deleted when this class desctructor is called.
+ */
+struct Timer {
+  Timer(const Timer &) = delete;
+
+  Timer(Timer &) = delete;
+
+  Timer &operator=(Timer &) = delete;
+
+  explicit Timer(esp_timer_create_args_t args) :
+      args_(args), esp_timer_(nullptr)
+  {
+    ESP_LOGI(TAG, "Creating esp_timer with name: %s", args_.name);
+    ESP_ERROR_CHECK(esp_timer_create(&args, &esp_timer_));
+  }
+
+  ~Timer()
+  {
+    ESP_LOGI(TAG, "Destroying esp_timer with name: %s", args_.name);
+    ESP_ERROR_CHECK(esp_timer_delete(esp_timer_));
+  }
+
+  /// Arguments passed to ESP API during timer creation.
+  esp_timer_create_args_t args_;
+
+  /// ESP timer handle.
+  esp_timer_handle_t esp_timer_;
+};
+
+/**
+ * ESP timer mananger class.
+ *
+ * Timers should only be accessed using the get_handle method.
+ * If the Timer destructor is called the underlying ESP timer will be deleted.
+ */
+struct TimeKeeper {
+  /// Timer handle type used for referring to Timers.
+  using TimerHandle = Timer *;
+
+  TimerHandle get_handle(const char *name)
+  {
+    return &managed_timers_.at(name);
+  }
+
+  TimerHandle operator[](const char *name) { return get_handle(name); }
+
+  /**
+   * Create a new managed Timer with the provided ESP arguments.
+   * The timer can be retrieved later using the args.name field value.
+   *
+   * @param args ESP timer creation arguments.
+   * @return TimerHandle Handle to a Timer managed by this TimeKeeper.
+   * @sa get_handle
+   * @sa operator[](const char*)
+   */
+  TimerHandle create_timer(esp_timer_create_args_t args)
+  {
+    auto rt = managed_timers_.emplace(args.name, args);
+    if (!rt.second) {
+      ESP_LOGE(TAG, "Display::Timer already exists with name %s", args.name);
+      return nullptr;
+    }
+    return &rt.first->second;
+  }
+
+  /// Stop a Timer with the given name.
+  [[maybe_unused]] void stop_timer(const char *name)
+  {
+    ESP_ERROR_CHECK(esp_timer_stop(get_handle(name)->esp_timer_));
+  }
+
+  /// Delete a Timer with the given name.
+  [[maybe_unused]] void delete_timer(const char *name)
+  {
+    managed_timers_.erase(name);
+  }
+
+  /// Create a Timer with the ESP args and call esp_timer_start_periodic.
+  [[maybe_unused]] void
+  start_new_timer_periodic(esp_timer_create_args_t args,
+                           uint64_t period)
+  {
+    start_timer_periodic(create_timer(args)->args_.name, period);
+  }
+
+  /// Calls esp_timer_start_periodic on the Timer with the given name.
+  [[maybe_unused]] void start_timer_periodic(const char *name,
+                                             uint64_t period)
+  {
+    ESP_ERROR_CHECK(
+        esp_timer_start_periodic(get_handle(name)->esp_timer_, period));
+  }
+
+  /// Create a Timer with the ESP args and call esp_timer_start_once.
+  [[maybe_unused]] void
+  start_new_timer_once(esp_timer_create_args_t args,
+                       uint64_t timeout_us)
+  {
+    start_timer_once(create_timer(args)->args_.name, timeout_us);
+  }
+
+  /// Calls esp_timer_start_once on the Timer with the given name.
+  [[maybe_unused]] void start_timer_once(const char *name,
+                                         uint64_t timeout_us)
+  {
+    ESP_ERROR_CHECK(
+        esp_timer_start_once(get_handle(name)->esp_timer_, timeout_us));
+  }
+
+private:
+  /// Existing ESP timers created for this TimeKeeper instance.
+  std::unordered_map<const char *, Timer> managed_timers_;
+};
+
+#endif // TIME_KEEPER_H

esp/cpp/07_lcd-panel/README.md

@@ -1,33 +0,0 @@
-# 06_lcd-panel
-
-This example is largely adapted from those in [ESP32-basic-starter-kit.pdf](./ESP32-basic-starter-kit.pdf).
-
-The APIs in the original examples paired with this PDF have changed, and I decided to do some different things with the code and/or circuits, but the original code can be [found here](https://www.dropbox.com/scl/fo/6znlij3eb23ih4jxcpv2w/AKvB1t9CCUgoVRVtGen8Yrw?rlkey=z84anl0hs940qf9fpl7l8q8q2&e=1&dl=0).
-
-This is the same example in [03_temp-humidity-web](./../03_temp-humidity-web), ported to the cmake ESP-IDF build system.
-
-For instructions on setting up the ESP-IDF see [04_-esp-idf-arduino](./../04_esp-idf-arduino)
-
-This example is largely adapted from those in [ESP32-basic-starter-kit.pdf](./ESP32-basic-starter-kit.pdf).
-
-The APIs in the original examples paired with this PDF have changed, and I decided to do some different things with the code and/or circuits, but the original code can be [found here](https://www.dropbox.com/scl/fo/6znlij3eb23ih4jxcpv2w/AKvB1t9CCUgoVRVtGen8Yrw?rlkey=z84anl0hs940qf9fpl7l8q8q2&e=1&dl=0).
-
-![schematic](./schematic.png)
-
-Temperature and humidity sensor served on a web page within the local network.
-
-![screenshot](./screenshot.png)
-
-To build this example run the following commands.
-
-```bash
-source ~/path/to/esp-idf/export.sh
-
-mkdir build
-cd build
-cmake ..
-make -j $(nproc)
-make flash
-```
-
-[ESP-IDF I2C documentation](https://docs.espressif.com/projects/esp-idf/en/stable/esp32/api-reference/peripherals/i2c.html)

esp/cpp/07_lcd-panel/main/CMakeLists.txt

@@ -1,5 +0,0 @@
-idf_component_register(
-    SRCS main.cpp display.cpp panel_device.cpp ssd1306.cpp
-    INCLUDE_DIRS .
-    REQUIRES driver
-)

esp/cpp/07_lcd-panel/main/display.h

@@ -1,105 +0,0 @@
-#ifndef DISPLAY_H
-#define DISPLAY_H
-
-#include <esp_lcd_types.h>
-#include <esp_lcd_panel_ssd1306.h>
-#include <driver/i2c_types.h>
-#include <driver/i2c_master.h>
-#include <unordered_map>
-#include <esp_lcd_panel_ops.h>
-#include <esp_lcd_panel_io.h>
-#include "misc/lv_types.h"
-#include "misc/lv_area.h"
-#include "display/lv_display.h"
-#include "widgets/label/lv_label.h"
-
-#include "panel_device.h"
-
-#define I2C_BUS_PORT  0
-#define LVGL_TICK_PERIOD_MS    5
-#define LVGL_TASK_STACK_SIZE   (4 * 1024)
-#define LVGL_TASK_PRIORITY     2
-
-struct I2C {
-  I2C(gpio_num_t sda, gpio_num_t scl);
-
-  ~I2C() = default;
-
-  i2c_master_bus_handle_t i2c_bus_;
-
-private:
-  i2c_master_bus_config_t bus_config_;
-};
-
-struct ScopedLock {
-  explicit ScopedLock() { _lock_acquire(&lock_); }
-
-  ~ScopedLock() { _lock_release(&lock_); }
-
-  // LVGL library is not thread-safe, this example calls LVGL APIs from tasks.
-  // We must use a mutex to protect it.
-  static _lock_t lock_;
-};
-
-class Panel {
-public:
-  explicit Panel(IPanelDevice *device);
-
-  ~Panel() = default;
-
-  IPanelDevice *device_;
-
-  esp_lcd_panel_io_handle_t io_handle_;
-
-  esp_lcd_panel_handle_t esp_panel_;
-
-private:
-  esp_lcd_panel_dev_config_t panel_config_;
-};
-
-class Display {
-public:
-  explicit Display(IPanelDevice *device);
-
-  ~Display() = default;
-
-  [[nodiscard]] inline const lv_display_t *get() const { return lv_display_; }
-
-  [[nodiscard]] inline lv_display_t *get() { return lv_display_; }
-
-  [[nodiscard]] inline const lv_display_t *operator*() const { return get(); }
-
-  [[nodiscard]] inline lv_display_t *operator*() { return get(); }
-
-  void set_text(const char *text,
-                const char *name,
-                lv_label_long_mode_t long_mode = LV_LABEL_LONG_SCROLL_CIRCULAR,
-                lv_align_t align = LV_ALIGN_TOP_MID);
-
-  static bool lvgl_flush_ready(esp_lcd_panel_io_handle_t panel,
-                               esp_lcd_panel_io_event_data_t *data,
-                               void *user_ctx);
-
-  static void lvgl_flush_cb(lv_display_t *display,
-                            const lv_area_t *area,
-                            uint8_t *px_map);
-
-  static void lvgl_increase_tick(void *arg);
-
-  [[noreturn]] static void lvgl_port_task(void *arg);
-
-private:
-  Panel panel_;
-
-  lv_display_t *lv_display_;
-
-  // Draw buffer associated with the lv_display_t.
-  void *lv_buf_;
-
-  // Objects stored in the screen associated with this display.
-  // @sa Display::set_text
-  // @sa lv_display_get_screen_active
-  std::unordered_map<const char *, lv_obj_t *> objects_;
-};
-
-#endif // DISPLAY_H

esp/cpp/07_lcd-panel/main/main.h

@@ -1,4 +0,0 @@
-#ifndef  MAIN_H
-#define  MAIN_H
-
-#endif // MAIN_H

esp/cpp/07_lcd-panel/main/panel_device.cpp

@@ -1,2 +0,0 @@
-
-#include "panel_device.h"

esp/cpp/07_lcd-panel/main/ssd1306.cpp

@@ -1,37 +0,0 @@
-
-#include "ssd1306.h"
-
-// To use LV_COLOR_FORMAT_I1 we need an extra buffer to hold the converted data.
-uint8_t SSD1306::oled_buffer_[LCD_H_RES * LCD_V_RES / 8];
-
-SSD1306::SSD1306(i2c_master_bus_handle_t i2c,
-                 esp_lcd_panel_ssd1306_config_t config,
-                 int width,
-                 int height) :
-    IPanelDevice(i2c,
-                 PIN_RST,
-                 (esp_lcd_panel_io_i2c_config_t) {
-                     .dev_addr = I2C_HW_ADDR,
-                     .control_phase_bytes = 1,
-                     .dc_bit_offset = 6,
-                     .lcd_cmd_bits = LCD_CMD_BITS,
-                     .lcd_param_bits = LCD_CMD_BITS,
-                     .scl_speed_hz = LCD_PIXEL_CLOCK_HZ,
-                 }
-    ),
-    ssd1306_config_(config)
-{
-  this->width_ = width;
-  this->height_ = height;
-  this->reset_gpio_num_ = PIN_RST;
-  this->lv_buf_size_ = width_ * height_ / 8 + LVGL_PALETTE_SIZE;
-}
-
-void SSD1306::init_panel(esp_lcd_panel_dev_config_t &config,
-                         esp_lcd_panel_io_handle_t io,
-                         esp_lcd_panel_handle_t &panel)
-{
-  // Allocate SSD1306 panel handle.
-  config.vendor_config = &ssd1306_config_;
-  ESP_ERROR_CHECK(esp_lcd_new_panel_ssd1306(io, &config, &panel));
-}

esp/cpp/07_lcd-panel/main/ssd1306.h

@@ -1,48 +0,0 @@
-#ifndef SSD1306_H
-#define SSD1306_H
-
-#include <esp_lcd_panel_ssd1306.h>
-
-#include "panel_device.h"
-
-// According to SSD1306 datasheet
-// https://www.digikey.com/en/products/detail/winstar-display/WEA012864DWPP3N00003/20533255
-// Bit number used to represent command and parameter
-#define SCREEN_WIDTH           128  // OLED display width, in pixels.
-#define SCREEN_HEIGHT          64  // OLED display height, in pixels.
-#define LCD_H_RES              SCREEN_WIDTH
-#define LCD_V_RES              SCREEN_HEIGHT
-#define I2C_HW_ADDR            0x3C
-#define LCD_PIXEL_CLOCK_HZ     (400 * 1000)
-#define LCD_CMD_BITS           8
-#define LCD_PARAM_BITS         8
-
-#define PIN_RST                -1
-
-class SSD1306 : public IPanelDevice {
-public:
-  // Constructors allow overriding ssd1306 config.
-  explicit SSD1306(i2c_master_bus_handle_t i2c) :
-      SSD1306(i2c, {.height = SCREEN_HEIGHT}) { }
-
-  explicit SSD1306(i2c_master_bus_handle_t i2c,
-                   esp_lcd_panel_ssd1306_config_t config,
-                   int width = SCREEN_WIDTH,
-                   int height = SCREEN_HEIGHT);
-
-  virtual ~SSD1306() = default;
-
-  // The configuration structure specific to the SSD1306.
-  esp_lcd_panel_ssd1306_config_t ssd1306_config_;
-
-  // For LV_COLOR_FORMAT_I1 we need an extra buffer to hold the converted data.
-  static uint8_t oled_buffer_[LCD_H_RES * LCD_V_RES / 8];
-
-private:
-  void init_panel(esp_lcd_panel_dev_config_t &config,
-                  esp_lcd_panel_io_handle_t io,
-                  esp_lcd_panel_handle_t &panel) override;
-
-};
-
-#endif // SSD1306_H