Add IPanelDevice.

E (413) i2c: CONFLICT! driver_ng is not allowed to be used with this old driver

esp/cpp/06_i2c-scanner/.gitignore

@@ -0,0 +1,4 @@
+build
+managed_components
+dependencies.lock
+sdkconfig.old

esp/cpp/06_i2c-scanner/CMakeLists.txt

@@ -0,0 +1,17 @@
+# For more information about build system see
+# https://docs.espressif.com/projects/esp-idf/en/latest/api-guides/build-system.html
+# The following five lines of boilerplate have to be in your project's
+# CMakeLists in this exact order for cmake to work correctly
+cmake_minimum_required(VERSION 3.26)
+
+include($ENV{IDF_PATH}/tools/cmake/project.cmake)
+
+project(
+    #[[NAME]]   i2c-scanner
+    VERSION     0.1
+    DESCRIPTION "Simple I2C device scanner"
+    LANGUAGES   CXX
+)
+# For writing pure cmake components, see the documentation
+# https://docs.espressif.com/projects/esp-idf/en/stable/esp32/api-guides/build-system.html#writing-pure-cmake-components
+idf_build_set_property(COMPILE_OPTIONS "-Wno-error" APPEND)

esp/cpp/06_i2c-scanner/README.md

@@ -0,0 +1,32 @@
+# 06_i2c-scanner
+
+![schematic](./schematic.png)
+
+Simple I2C device scanner.
+
+For this example I used this [SSD1306 OLED display](https://www.digikey.com/en/products/detail/winstar-display/WEA012864DWPP3N00003/20533255).
+
+To build the example run the following commands.
+
+```bash
+source ~/path/to/esp-idf/export.sh
+
+mkdir build
+cd build
+cmake ..
+make -j $(nproc)
+
+# Flash to ESP32
+make flash
+
+# Open Serial Monitor, press CTRL+] to exit.
+make monitor
+```
+
+Expected output in serial monitor at 115200 baud
+
+```bash
+Scanning I2C devices...
+[0x3c]: Device found with clock rate 100000 and timeout 50
+Done.
+```

esp/cpp/06_i2c-scanner/main/CMakeLists.txt

@@ -0,0 +1,4 @@
+idf_component_register(
+    SRCS "main.cpp"
+    INCLUDE_DIRS "."
+)

esp/cpp/06_i2c-scanner/main/idf_component.yml

@@ -0,0 +1,17 @@
+## IDF Component Manager Manifest File
+dependencies:
+  ## Required IDF version
+  idf:
+    version: '>=4.1.0'
+  # # Put list of dependencies here
+  # # For components maintained by Espressif:
+  # component: "~1.0.0"
+  # # For 3rd party components:
+  # username/component: ">=1.0.0,<2.0.0"
+  # username2/component2:
+  #   version: "~1.0.0"
+  #   # For transient dependencies `public` flag can be set.
+  #   # `public` flag doesn't have an effect dependencies of the `main` component.
+  #   # All dependencies of `main` are public by default.
+  #   public: true
+  espressif/arduino-esp32: ^3.1.1

esp/cpp/06_i2c-scanner/main/main.cpp

@@ -0,0 +1,35 @@
+#include "Arduino.h"
+#include "Wire.h"
+
+[[maybe_unused]] static const char *TAG = "i2c-scanner";
+
+void i2c_scan()
+{
+  uint8_t device_num = 0;
+  Serial.println("Scanning I2C devices...");
+  for (byte address = 1; address < 127; address++) {
+    Wire.beginTransmission(address);
+    byte error = Wire.endTransmission();
+    if (error == 0) {
+      Serial.printf(
+          "[0x%.2x]: Device found with clock rate %lu and timeout %u\n",
+          address,
+          Wire.getClock(), Wire.getTimeOut());
+      device_num++;
+    } else if (error == 4) {
+      Serial.printf("[0x%.2x]: Unknown error.\n", address);
+    }
+  }
+  Serial.println(device_num > 0 ? "Done.\n" : "No I2C devices found.\n");
+}
+
+void setup()
+{
+  Serial.begin(115200);
+  Wire.begin();
+}
+
+void loop()
+{
+  i2c_scan();
+}

esp/cpp/07_lcd-panel/.gitignore

@@ -0,0 +1,4 @@
+build
+managed_components
+dependencies.lock
+sdkconfig.old

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

@@ -0,0 +1,17 @@
+# For more information about build system see
+# https://docs.espressif.com/projects/esp-idf/en/latest/api-guides/build-system.html
+# The following five lines of boilerplate have to be in your project's
+# CMakeLists in this exact order for cmake to work correctly
+cmake_minimum_required(VERSION 3.26)
+
+include($ENV{IDF_PATH}/tools/cmake/project.cmake)
+
+project(
+    #[[NAME]]   lcd-panel
+    VERSION     0.1
+    DESCRIPTION "Example of using the SSD1306 LCD display with ESP-IDF and LVGL"
+    LANGUAGES   CXX
+)
+# For writing pure cmake components, see the documentation
+# https://docs.espressif.com/projects/esp-idf/en/stable/esp32/api-guides/build-system.html#writing-pure-cmake-components
+idf_build_set_property(COMPILE_OPTIONS "-Wno-error" APPEND)

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

@@ -0,0 +1,33 @@
+# 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

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

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

@@ -0,0 +1,212 @@
+
+#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>
+
+// 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_;
+
+Display::Display(IPanelDevice *device) :
+    panel_(device)
+{
+  if (!lv_is_initialized()) {
+    ESP_LOGI(TAG, "Initialize LVGL");
+    lv_init();
+  }
+
+  // Create a 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_);
+
+  // 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");
+  xTaskCreate(Display::lvgl_port_task, "LVGL", LVGL_TASK_STACK_SIZE,
+              nullptr, LVGL_TASK_PRIORITY, nullptr);
+}
+
+void Display::set_text(const char *text,
+                       const char *name,
+                       lv_label_long_mode_t long_mode,
+                       lv_align_t align)
+{
+  // Lock the mutex due to the LVGL APIs are not thread-safe.
+  ScopedLock lock;
+
+  ESP_LOGI(TAG, "Display LVGL Scroll Text");
+  lv_obj_t *scr = lv_display_get_screen_active(lv_display_);
+  objects_[name] = lv_label_create(scr);
+
+  // Circular scroll.
+  auto obj = objects_[name];
+  lv_label_set_long_mode(obj, long_mode);
+  lv_label_set_text(obj, text);
+
+  // Set the size of the screen.
+  // If you use rotation 90 or 270 use lv_display_get_vertical_resolution.
+  lv_obj_set_width(obj, lv_display_get_horizontal_resolution(lv_display_));
+  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)
+{
+  auto *disp = (lv_display_t *) user_ctx;
+  lv_display_flush_ready(disp);
+  return false;
+}
+
+void Display::lvgl_flush_cb(lv_display_t *display, const lv_area_t *area,
+                            uint8_t *px_map)
+{
+  auto panel_handle =
+      (esp_lcd_panel_handle_t) lv_display_get_user_data(display);
+
+  // Necessary because LVGL reserves 2x4 bytes in the buffer for a palette.
+  // For more information about the monochrome, please refer to:
+  // https://docs.lvgl.io/9.2/porting/display.html#monochrome-displays
+  // Skip the palette here.
+  px_map += LVGL_PALETTE_SIZE;
+
+  uint16_t hor_res = lv_display_get_physical_horizontal_resolution(display);
+  int32_t x1 = area->x1;
+  int32_t x2 = area->x2;
+  int32_t y1 = area->y1;
+  int32_t y2 = area->y2;
+
+  for (int32_t y = y1; y <= y2; y++) {
+    for (int32_t x = x1; x <= x2; x++) {
+      /* The order of bits is MSB first.
+                  MSB           LSB
+         bits      7 6 5 4 3 2 1 0
+         pixels    0 1 2 3 4 5 6 7
+                  Left         Right
+      */
+      bool chroma_color = (px_map[(hor_res >> 3) * y + (x >> 3)] &
+                           1 << (7 - x % 8));
+
+      // Write to the buffer as required for the display.
+      // It writes only 1-bit for monochrome displays mapped vertically.
+      uint8_t *buf = SSD1306::oled_buffer_ + hor_res * (y >> 3) + (x);
+      if (chroma_color) {
+        (*buf) &= ~(1 << (y % 8));
+      } else {
+        (*buf) |= (1 << (y % 8));
+      }
+    }
+  }
+  // Pass the draw buffer to the driver.
+  ESP_ERROR_CHECK(
+      esp_lcd_panel_draw_bitmap(panel_handle, x1, y1, x2 + 1, y2 + 1,
+                                SSD1306::oled_buffer_));
+}
+
+void Display::lvgl_increase_tick(void *)
+{
+  // Tell LVGL how many milliseconds has elapsed
+  lv_tick_inc(LVGL_TICK_PERIOD_MS);
+}
+
+[[noreturn]] void Display::lvgl_port_task(void *)
+{
+  ESP_LOGI(TAG, "Starting LVGL task");
+  for (uint32_t time_till_next_ms = 0; true;) {
+    _lock_acquire(&ScopedLock::lock_);
+    time_till_next_ms = lv_timer_handler();
+    _lock_release(&ScopedLock::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,
+            },
+        }
+    )
+{
+  ESP_LOGI(TAG, "Initialize I2C bus");
+  ESP_ERROR_CHECK(i2c_new_master_bus(&bus_config_, &i2c_bus_));
+}
+
+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
+        }
+    )
+{
+  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/cpp/07_lcd-panel/main/display.h

@@ -0,0 +1,105 @@
+#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/idf_component.yml

@@ -0,0 +1,5 @@
+## IDF Component Manager Manifest File
+dependencies:
+  espressif/arduino-esp32: ^3.1.1
+  lvgl/lvgl: "9.2.0"
+  esp_lcd_sh1107: "^1"

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

@@ -0,0 +1,31 @@
+#include "display.h"
+#include "ssd1306.h"
+
+// Pin may vary based on your schematic.
+#define PIN_SDA                GPIO_NUM_21
+#define PIN_SCL                GPIO_NUM_22
+#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);
+
+void setup()
+{
+  SSD1306 ssd1306(i2c.i2c_bus_);
+  Display d(&ssd1306);
+
+  d.set_text("Test test 12345678910",
+             "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.",
+             "test-text3",
+             LV_LABEL_LONG_CLIP,
+             LV_ALIGN_BOTTOM_MID);
+}
+
+void loop() { }

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

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

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

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

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

@@ -0,0 +1,65 @@
+#ifndef PANEL_DEVICE_H
+#define PANEL_DEVICE_H
+
+#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"
+
+#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) { }
+
+  virtual ~IPanelDevice() = default;
+
+  [[nodiscard]] lv_display_t *create_display() const
+  {
+    auto display = lv_display_create(width_, height_);
+    assert(display);
+    return display;
+  }
+
+  void create_panel(esp_lcd_panel_dev_config_t &config,
+                    esp_lcd_panel_io_handle_t io,
+                    esp_lcd_panel_handle_t &panel)
+  {
+    // If the passed handle is already allocated, delete it.
+    if (panel != nullptr) {
+      ESP_LOGI(TAG, "Removing unused panel");
+      esp_lcd_panel_del(panel);
+    }
+
+    ESP_LOGI(TAG, "Install SSD1306 panel driver");
+    init_panel(config, io, panel);
+  }
+
+  int32_t width_;
+  int32_t height_;
+  int reset_gpio_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_;
+
+private:
+  virtual void init_panel(esp_lcd_panel_dev_config_t &config,
+                          esp_lcd_panel_io_handle_t io,
+                          esp_lcd_panel_handle_t &panel) = 0;
+};
+
+#endif // PANEL_DEVICE_H

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

@@ -0,0 +1,37 @@
+
+#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

@@ -0,0 +1,48 @@
+#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

esp/cpp/README.md

@@ -7,6 +7,7 @@ shaunrd0/klips/esp/
 ├── 03_temp-humidity-web        # Temperature and humidity sensor within a web browser.
 ├── 04_esp-idf-arduino          # CMake example instead of Arduino IDE for ESP development.
 ├── 05_temp-humidity-web        # Temperature and humidity sensor within a web browser.
+├── 06_i2c-scanner              # Simple I2C device scanner.
 ├── ESP32-basic-starter-kit.pdf # PDF for tutorials in ESP32 starter kit.
 ├── ESP32-dev-module.png
 └── README.md