/*############################################################################# ## Author: Shaun Reed ## ## Legal: All Content (c) 2025 Shaun Reed, all rights reserved ## ## ## ## Contact: shaunrd0@gmail.com | URL: www.shaunreed.com ## ############################################################################## */ #ifndef PANEL_DEVICE_H #define PANEL_DEVICE_H #include #include #include #include #include #include // TODO: Remove static esp_timer_handle_t esp_timer_; #include /// Tag used for ESP logging. static const char* LCD_TAG = "LCD component"; // LVGL library is not thread-safe, this example calls LVGL APIs from tasks. // We must use a mutex to protect it. static _lock_t lv_lock_; // LVGL reserves 2x4 bytes in the buffer to be used as a palette. // This additional space must be added to the IPanelDevice::buf_size_. #define LVGL_PALETTE_SIZE 8 #define LVGL_TICK_PERIOD_MS 5 #define LVGL_TASK_STACK_SIZE (4 * 1024) #define LVGL_TASK_PRIORITY 2 #define LCD_H_RES 128 #define LCD_V_RES 64 // 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 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 /** * Calculate byte offset for the pixel at [x,y] within a horizontally-mapped * monochrome uint8 draw buffer, using the initialized horizontal resolution. * * We use `>> 3` because each pixel requires 1 bit, but each uint8 in the draw * buffer can hold 8 bits. To find the uint8 value in our draw buffer that * stores this pixel's value we must compensate for this when using pixel * coordinates in byte math. * * Therefore, each uint8 in the draw buffer stores the state of 8 pixels. * Below is an example of calculating for [x, y] pixel coordinates [20, 10]. * The example uses a horizontal resolution of 128. * * For the horizontal case, each row (y) of the image is represented by * `hor_res >> 3` bytes (16). The byte-offset of the first pixel in the 10th * row for example is `16 * 10` = 160. * * Since the pixels are stored horizontally we must calculate the 20th pixel * column (x) as `160 + (20 >> 3)`, or `160 + (20 / 8)` to get a final offset * of 162. * * @param x X pixel coordinate to find byte offset. * @param y Y pixel coordinate to find byte offset. * @param hor_res horizontal resolution of the display. * @return byte offset for a single-byte monochrome pixel at [x,y]. */ static ptrdiff_t horizontal_byte_offset_long(const int32_t x, const int32_t y, const int32_t hor_res) { // Convert pixel (bit) coordinates to byte coordinates in the draw buffer. return (hor_res >> 3) * y + (x >> 3); } static ptrdiff_t horizontal_byte_offset(const int32_t x, const int32_t y) { return horizontal_byte_offset_long(x, y, LCD_V_RES); } /** * Calculate byte offset for the pixel at [x,y] within a vertically-mapped * monochrome uint8 draw buffer, using the initialized horizontal resolution. * * We use `>> 3` because each pixel requires 1 bit, but each uint8 in the draw * buffer can hold 8 bits. To find the uint8 value in our draw buffer that * stores this pixel's value we must compensate for this when using pixel * coordinates in byte math. * * Therefore, each uint8 in the draw buffer stores the state of 8 pixels. * Below is an example of calculating for [x, y] pixel coordinates [20, 10]. * The example uses a horizontal resolution of 128. * * For the vertical case, each row (y) of the image is represented by * `hor_res` bytes (128) - one for each column (x). Because the pixels are * stored vertically, the byte-offset of the first pixel in the 10th row is * `128 * (10 >> 3)` or * `128 * (10 / 8)` = 128. * * From this location we can simply calculate the 20th pixel column (x) as * `128 + 20` to get a final offset of 148, because the pixels are stored in a * columnar format. * * @param x X pixel coordinate to find byte offset. * @param y Y pixel coordinate to find byte offset. * @param hor_res horizontal resolution of the display. * @return byte offset for a single-byte monochrome pixel at [x,y]. */ static ptrdiff_t vertical_byte_offset_long(const int32_t x, const int32_t y, const int32_t hor_res) { // Convert pixel (bit) coordinates to byte coordinates in the draw buffer. return hor_res * (y >> 3) + x; } static ptrdiff_t vertical_byte_offset(const int32_t x, const int32_t y) { return vertical_byte_offset_long(x, y, LCD_V_RES); } /** * Finds the Most Significant Bit location of bit `i` in a byte. * * MSB LSB * bits 7 6 5 4 3 2 1 0 * data 8 7 6 5 4 3 2 1 * Left Right * * @return bitmask for MSB location of `i`. */ static uint8_t msb_mask(const int32_t i) { return 1 << (7 - i % 8); } /** * Finds the Least Significant Bit location of bit `i` in a byte. * * LSB MSB * bits 0 1 2 3 4 5 6 7 * data 1 2 3 4 5 6 7 8 * Left Right * * @return bitmask for LSB location of `i`. */ static uint8_t lsb_mask(const int32_t i) { return 1 << (i % 8); } static uint8_t* get_additional_draw_buffer() { // Static to the scope of this function, not the compilation unit. // For LV_COLOR_FORMAT_I1 we need an extra buffer to hold converted data. static uint8_t oled_buffer[LCD_H_RES * LCD_V_RES / 8]; return oled_buffer; } /** * Retrieve the device specific vendor configuration structure. * * @return Address of vendor configuration structure. */ typedef void* (*vendor_config_cb_t)(); /** * Registers LVGL ticker timer callback for rendering this display. * * An implementation of the interface can optionally override this method to * provide custom LVGL callbacks and tick configurations. */ typedef void (*register_lvgl_tick_timer_cb_t)(); /** * Initializes the ESP panel using vendor specific APIs and configurations. * This method should implement any setup logic specific to the device. * * @param config ESP LCD panel configuration. * @param io ESP LCD panel IO handle. * @param [out] panel ESP LCD panel handle output pointer location. */ typedef void (*init_panel_cb_t)(esp_lcd_panel_dev_config_t* config, esp_lcd_panel_io_handle_t io, esp_lcd_panel_handle_t* panel); /** * Registers LVGL draw buffers and callbacks for this display. * * An implementation of the interface can optionally override this method to * provide custom LVGL callbacks and display configurations. * * @param display_handle LVGL display handle to use for rendering. * @param io_handle IO handle for the ESP LCD panel. */ typedef void (*register_rendering_data_cb_t)( lv_display_t* display_handle, esp_lcd_panel_io_handle_t io_handle, void*, size_t); /** * Encapsulates vendor specific ESP LCD panel initialization logic. * This pure virtual interface can be inherited from for using new LCD devices. * See SSD1306 as an example to implement IPanelDevice for NT35510 or ST7789. * * At this time only I2C is supported. * Classes that inherit from this interface should likely be marked final. */ struct IPanelDevice { /// Width of the device screen in pixels. int32_t width_; /// Height of the device screen in pixels. int32_t height_; /// RST GPIO pin number. int rst_num_; /// LVGL draw buffer size for the device. size_t lv_buf_size_; /// ESP LCD panel IO configuration. esp_lcd_panel_io_i2c_config_t esp_io_config_; /// LVGL draw buffer associated with this Display's lv_display_t. void* lv_buf_; /// Callback used to initialize the ESP panel. /// TODO: Assert by default? init_panel_cb_t init_panel_cb; /// Callback used to register LVGL tick timer. register_lvgl_tick_timer_cb_t register_lvgl_tick_timer_cb; /// Callback used to register LVGL draw buffers. register_rendering_data_cb_t register_rendering_data_cb; /// Callback used to fetch the display vendor configuration. vendor_config_cb_t vendor_config_cb; }; /** * Static accessor to a static buffer to store draw buffer data for the panel. * * This method is protected to allow an implementation to provide a custom * callback method similar to IPanelDevice::lvgl_flush_cb. * * The buffer is allocated statically within the scope of this function to * allow creating multiple panels that _each_ manage their own statically * allocated draw buffer data. This simplifies implementing the interface by * taking this responsibility off of the implementor. The buffer will only be * allocated if this method is called, so the memory is only used if required. * * @return Pointer to uint8 draw buffer data. * @sa register_rendering_data for overriding LVGL rendering callbacks. */ /** * The callback invoked when panel IO finishes transferring color data. * This signals that the panel is ready to flush image data to the display. * * @param panel LCD panel IO handles. * @param data Panel IO event data, fed by driver. * @param user_ctx User data, passed from `esp_lcd_panel_io_xxx_config_t`. * @return Whether a high priority task has been waken up by this function. * @sa register_rendering_data for overriding this callback. */ static bool lvgl_flush_ready_cb(esp_lcd_panel_io_handle_t panel, esp_lcd_panel_io_event_data_t* data, void* user_ctx) { lv_display_t* disp = (lv_display_t*)user_ctx; lv_display_flush_ready(disp); return false; } /** * The callback invoked for flushing the rendered image to the display. * * `px_map` contains the rendered image as raw pixel map and it should be * copied to `area` on the display. * * The following details are crucial for understanding the logic surrounding * flushing to the display in this example. * * The order of bits within the px_map from _LVGL_ 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 * * The bytes from _LVGL_ are mapped to pixel rows of the display * 8 bits (pixels) per byte - * [0, 0, 0, 0, 0, 0, 0, 0] * [0, 0, 0, 0, 0, 0, 0, 0] * [0, 0, 0, 0, 0, 0, 0, 0] * * The order of bits expected by the _display driver_ is LSB first. * We must preserve pairing of each bit and pixel when writing to the display. * LSB MSB * bits 0 1 2 3 4 5 6 7 * pixels 7 6 5 4 3 2 1 0 * Left Right * * Bytes expected by the _display driver_ map to pixel columns of the display. * 8 bits (pixels) per byte - * [0, [0, [0, [0, * 0, 0, 0, 0, * 0, 0, 0, 0, * 0, 0, 0, 0, * 0, 0, 0, 0, * 0, 0, 0, 0, * 0, 0, 0, 0, * 0] 0] 0] 0] * * These layouts in memory have no opinion on the shape of the image. The * beginning and end of a row or a column for example is entirely dependent * on how the data is accessed. The vertical and horitzontal resolution may * vary between displays. * * For the LV_COLOR_FORMAT_I1 color format we are using, an additional buffer * is needed for transposing the bits to the vertical arrangement required by * the display driver that is outlined above. * * This callback implementation is an example of handling this transposition * and flushing the data to the display in the expected format. * * @param display LVGL display handle to use for rendering. * @param area Area of the display being flushed. * @param px_map Rendered image data for writing to the display area. * @sa register_rendering_data for overriding this callback. * @sa get_additional_draw_buffer */ static void lvgl_flush_cb(lv_display_t* display, const lv_area_t* area, uint8_t* px_map) { esp_lcd_panel_handle_t 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. // Since we are monochrome, we don't need these additional bytes. // 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; // As of 03/01/2025 master branch of LVGL contains this helper for the same. // https://docs.lvgl.io/master/API/draw/sw/lv_draw_sw_utils.html // lv_draw_sw_i1_convert_to_vtiled() for (int32_t y = y1; y <= y2; y++) { for (int32_t x = x1; x <= x2; x++) { // Get the byte offset of the pixel coordinates using // horizontal-mapping. int h_offset = horizontal_byte_offset_long(x, y, hor_res); // True if the pixel is lit, else false. bool chroma_color = px_map[h_offset] & msb_mask(x); // We need an additional buffer for transposing the pixel data to // the vertical format required by the display driver. uint8_t* buf = get_additional_draw_buffer(); // Move to the position in the auxillary buffer where the pixel is // stored. buf += vertical_byte_offset_long(x, y, hor_res); // Write the single bit to the monochrome display mapped vertically. // Take the Least Significant Bit mask of the Y coordinate to select // the bit representing a pixel at position y in a vertically-mapped // display. if (chroma_color) { // Set the vertically-mapped pixel to on. *buf &= ~lsb_mask(y); } else { // Set the vertically-mapped pixel to off. *buf |= lsb_mask(y); } } } // Pass the draw buffer to the driver. ESP_ERROR_CHECK(esp_lcd_panel_draw_bitmap( panel_handle, x1, y1, x2 + 1, y2 + 1, get_additional_draw_buffer())); } /** * Callback invoked for every period of the timer. * * This callback _must_ call lv_tick_inc to inform LVGL how much time has * elapsed since the last period of the timer. * * @param data User data passed to the callback. * @sa register_lvgl_tick_timer for setting user data and the tick period of * the timer, or overriding this callback entirely. */ static void lvgl_increase_tick_cb(void* data) { // Tell LVGL how many milliseconds has elapsed lv_tick_inc(LVGL_TICK_PERIOD_MS); } /** * FreeRTOS task callback invoked for handling LVGL events or updating the UI. * * This function is intentionally an endless loop and should never return. * LVGL initialization logic can optionally be added before entering the loop. * Input logic can optionally be handled within the loop. * * This callback _must_ call lv_timer_handler to handle LVGL periodic timers. * * @param data User data passed to the callback. * @sa register_lvgl_tick_timer for overriding this callback. */ [[noreturn]] static void lvgl_port_task(void* data) { // Optionally initialize some LVGL objects here before entering loop below. ESP_LOGI(LCD_TAG, "Starting LVGL task"); for (uint32_t time_to_next_ms = 0; true; usleep(1000 * time_to_next_ms)) { // Obtain LVGL API lock before calling any LVGL methods. _lock_acquire(&lv_lock_); // Optionally handle LVGL input or event logic here. // Update LVGL periodic timers. time_to_next_ms = lv_timer_handler(); _lock_release(&lv_lock_); } } /** * Registers LVGL ticker timer callback for rendering this display. * * An implementation of the interface can optionally override this method to * provide custom LVGL callbacks and tick configurations. */ static void register_lvgl_tick_timer() { ESP_LOGI(LCD_TAG, "Use esp_timer to increase LVGL tick"); const esp_timer_create_args_t esp_timer_args = { .callback = &lvgl_increase_tick_cb, // Data to pass to the lvgl_port_task callback. .arg = NULL, .name = "lvgl_tick", }; /// Start periodic ESP timer handle. ESP_LOGI(LCD_TAG, "Creating esp_timer with name: '%s'", esp_timer_args.name); ESP_ERROR_CHECK(esp_timer_create(&esp_timer_args, &esp_timer_)); ESP_ERROR_CHECK( esp_timer_start_periodic(esp_timer_, LVGL_TICK_PERIOD_MS * 1000)); ESP_LOGI(LCD_TAG, "Starting esp_timer with name: '%s'", esp_timer_args.name); // LVGL requires a FreeRTOS task for running it's event loop. // The lvgl_port_task callback can update the UI or handle input logic. // For this basic example we don't do either of these things. ESP_LOGI(LCD_TAG, "Create LVGL FreeRTOS task"); // Optionally set user data to pass to LVGL's FreeRTOS task callback here. void* user_data = NULL; xTaskCreate(lvgl_port_task, "LVGL", LVGL_TASK_STACK_SIZE, user_data, LVGL_TASK_PRIORITY, NULL); } static void register_rendering_data(lv_display_t* display_handle, esp_lcd_panel_io_handle_t io_handle, void* lv_buf, size_t lv_buf_size) { // Create draw buffer. ESP_LOGI(LCD_TAG, "Allocate separate LVGL draw buffers"); lv_buf = heap_caps_calloc(1, lv_buf_size, MALLOC_CAP_INTERNAL | MALLOC_CAP_8BIT); assert(lv_buf); ESP_LOGI(LCD_TAG, "Set LVGL draw buffers"); // Color format must be set first, LVGL9 support new monochromatic format. lv_display_set_color_format(display_handle, LV_COLOR_FORMAT_I1); lv_display_set_buffers(display_handle, lv_buf, NULL, lv_buf_size, LV_DISPLAY_RENDER_MODE_FULL); lv_display_set_rotation(display_handle, LV_DISPLAY_ROTATION_0); ESP_LOGI(LCD_TAG, "Set LVGL callback for flushing to the display"); lv_display_set_flush_cb(display_handle, lvgl_flush_cb); ESP_LOGI(LCD_TAG, "Register io panel callback for LVGL flush ready notification"); const esp_lcd_panel_io_callbacks_t cbs = { .on_color_trans_done = lvgl_flush_ready_cb, }; ESP_ERROR_CHECK(esp_lcd_panel_io_register_event_callbacks(io_handle, &cbs, display_handle)); } /// Callback used to fail, indicating the device is not fully initialized. static void* fail_vendor_config_cb() { ESP_LOGE(LCD_TAG, "Callback is unset: IPanelDevice::vendor_config_cb"); assert(false); } /// Callback used to fail, indicating the device is not fully initialized. static void fail_init_panel_cb(esp_lcd_panel_dev_config_t*, esp_lcd_panel_io_handle_t, esp_lcd_panel_handle_t*) { ESP_LOGE(LCD_TAG, "Callback is unset: IPanelDevice::init_panel_cb"); assert(false); } static struct IPanelDevice LCD_new_panel() { return (struct IPanelDevice){ .width_ = LCD_H_RES, .height_ = LCD_V_RES, .rst_num_ = -1, .lv_buf_size_ = LCD_H_RES * LCD_V_RES / 8 + LVGL_PALETTE_SIZE, .esp_io_config_ = (esp_lcd_panel_io_i2c_config_t){ .dev_addr = I2C_HW_ADDR, // User data to pass to the LVGL flush_ready callback. // See IPanelDevice::lvgl_flush_ready_cb .user_ctx = NULL, .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, }, .init_panel_cb = fail_init_panel_cb, // Must be assigned by caller .register_lvgl_tick_timer_cb = register_lvgl_tick_timer, .register_rendering_data_cb = register_rendering_data, .vendor_config_cb = fail_vendor_config_cb, // Must be assigned by caller }; } #endif // PANEL_DEVICE_H