Tactility/libs/esp_lvgl_port

LVGL ESP Portation

This component helps with using LVGL with Espressif's LCD and touch drivers. It can be used with any project with LCD display.

Features

• Initialization of the LVGL
  • Create task and timer
  • Handle rotating
• Add/remove display (using esp_lcd)
• Add/remove touch input (using esp_lcd_touch)
• Add/remove navigation buttons input (using button)
• Add/remove encoder input (using knob)

LVGL Version

This component supports LVGL8 and LVGL9. By default, it selects the latest LVGL version. If you want to use a specific version (e.g. latest LVGL8), you can easily put into idf_component.yml in your project like this:

  lvgl/lvgl:
    version: "^8"
    public: true

LVGL Version Compatibility

This component is fully compatible with LVGL version 9. All types and functions are used from LVGL9. Some LVGL9 types are not supported in LVGL8 and there are retyping in esp_lvgl_port_compatibility.h header file. Please, be aware, that some draw and object functions are not compatible between LVGL8 and LVGL9.

Usage

Initialization

    const lvgl_port_cfg_t lvgl_cfg = ESP_LVGL_PORT_INIT_CONFIG();
    esp_err_t err = lvgl_port_init(&lvgl_cfg);

Add screen

Add an LCD screen to the LVGL. It can be called multiple times for adding multiple LCD screens.

    static lv_disp_t * disp_handle;
    
    /* LCD IO */
	esp_lcd_panel_io_handle_t io_handle = NULL;
	ESP_ERROR_CHECK(esp_lcd_new_panel_io_spi((esp_lcd_spi_bus_handle_t) 1, &io_config, &io_handle));

    /* LCD driver initialization */ 
    esp_lcd_panel_handle_t lcd_panel_handle;
    ESP_ERROR_CHECK(esp_lcd_new_panel_st7789(io_handle, &panel_config, &lcd_panel_handle));

    /* Add LCD screen */
    const lvgl_port_display_cfg_t disp_cfg = {
        .io_handle = io_handle,
        .panel_handle = lcd_panel_handle,
        .buffer_size = DISP_WIDTH*DISP_HEIGHT,
        .double_buffer = true,
        .hres = DISP_WIDTH,
        .vres = DISP_HEIGHT,
        .monochrome = false,
        /* Rotation values must be same as used in esp_lcd for initial settings of the screen */
        .rotation = {
            .swap_xy = false,
            .mirror_x = false,
            .mirror_y = false,
        },
        .flags = {
            .buff_dma = true,
            .swap_bytes = false,
        }
    };
    disp_handle = lvgl_port_add_disp(&disp_cfg);
    
    /* ... the rest of the initialization ... */

    /* If deinitializing LVGL port, remember to delete all displays: */
    lvgl_port_remove_disp(disp_handle);

Add touch input

Add touch input to the LVGL. It can be called more times for adding more touch inputs.

    /* Touch driver initialization */
    ...
    esp_lcd_touch_handle_t tp;
    esp_err_t err = esp_lcd_touch_new_i2c_gt911(io_handle, &tp_cfg, &tp);

    /* Add touch input (for selected screen) */
    const lvgl_port_touch_cfg_t touch_cfg = {
        .disp = disp_handle,
        .handle = tp,
    };
    lv_indev_t* touch_handle = lvgl_port_add_touch(&touch_cfg);
    
    /* ... the rest of the initialization ... */

    /* If deinitializing LVGL port, remember to delete all touches: */
    lvgl_port_remove_touch(touch_handle);

Add buttons input

Add buttons input to the LVGL. It can be called more times for adding more buttons inputs for different displays. This feature is available only when the component espressif/button was added into the project.

    /* Buttons configuration structure */
    const button_config_t bsp_button_config[] = {
        {
            .type = BUTTON_TYPE_ADC,
            .adc_button_config.adc_channel = ADC_CHANNEL_0, // ADC1 channel 0 is GPIO1
            .adc_button_config.button_index = 0,
            .adc_button_config.min = 2310, // middle is 2410mV
            .adc_button_config.max = 2510
        },
        {
            .type = BUTTON_TYPE_ADC,
            .adc_button_config.adc_channel = ADC_CHANNEL_0, // ADC1 channel 0 is GPIO1
            .adc_button_config.button_index = 1,
            .adc_button_config.min = 1880, // middle is 1980mV
            .adc_button_config.max = 2080
        },
        {
            .type = BUTTON_TYPE_ADC,
            .adc_button_config.adc_channel = ADC_CHANNEL_0, // ADC1 channel 0 is GPIO1
            .adc_button_config.button_index = 2,
            .adc_button_config.min = 720, // middle is 820mV
            .adc_button_config.max = 920
        },
    };

    const lvgl_port_nav_btns_cfg_t btns = {
        .disp = disp_handle,
        .button_prev = &bsp_button_config[0],
        .button_next = &bsp_button_config[1],
        .button_enter = &bsp_button_config[2]
    };

    /* Add buttons input (for selected screen) */
    lv_indev_t* buttons_handle = lvgl_port_add_navigation_buttons(&btns);
    
    /* ... the rest of the initialization ... */

    /* If deinitializing LVGL port, remember to delete all buttons: */
    lvgl_port_remove_navigation_buttons(buttons_handle);

Note: When you use navigation buttons for control LVGL objects, these objects must be added to LVGL groups. See LVGL documentation for more info.

Add encoder input

Add encoder input to the LVGL. It can be called more times for adding more encoder inputs for different displays. This feature is available only when the component espressif/knob was added into the project.

    const button_config_t encoder_btn_config = {
        .type = BUTTON_TYPE_GPIO,
        .gpio_button_config.active_level = false,
        .gpio_button_config.gpio_num = GPIO_BTN_PRESS,
    };

    const knob_config_t encoder_a_b_config = {
        .default_direction = 0,
        .gpio_encoder_a = GPIO_ENCODER_A,
        .gpio_encoder_b = GPIO_ENCODER_B,
    };

    /* Encoder configuration structure */
    const lvgl_port_encoder_cfg_t encoder = {
        .disp = disp_handle,
        .encoder_a_b = &encoder_a_b_config,
        .encoder_enter = &encoder_btn_config
    };

    /* Add encoder input (for selected screen) */
    lv_indev_t* encoder_handle = lvgl_port_add_encoder(&encoder);
    
    /* ... the rest of the initialization ... */

    /* If deinitializing LVGL port, remember to delete all encoders: */
    lvgl_port_remove_encoder(encoder_handle);

Note: When you use encoder for control LVGL objects, these objects must be added to LVGL groups. See LVGL documentation for more info.

Add USB HID keyboard and mouse input

Add mouse and keyboard input to the LVGL. This feature is available only when the component usb_host_hid was added into the project.

    /* USB initialization */
    usb_host_config_t host_config = {
        .skip_phy_setup = false,
        .intr_flags = ESP_INTR_FLAG_LEVEL1,
    };
    ESP_ERROR_CHECK(usb_host_install(&host_config));

    ...

    /* Add mouse input device */
    const lvgl_port_hid_mouse_cfg_t mouse_cfg = {
        .disp = display,
        .sensitivity = 1, /* Sensitivity of the mouse moving */
    };
    lvgl_port_add_usb_hid_mouse_input(&mouse_cfg);

    /* Add keyboard input device */
    const lvgl_port_hid_keyboard_cfg_t kb_cfg = {
        .disp = display,
    };
    kb_indev = lvgl_port_add_usb_hid_keyboard_input(&kb_cfg);

Keyboard special behavior (when objects are in group):

• TAB: Select next object
• SHIFT + TAB: Select previous object
• ENTER: Control object (e.g. click to button)
• ARROWS or HOME or END: Move in text area
• DEL or Backspace: Remove character in textarea

Note: When you use keyboard for control LVGL objects, these objects must be added to LVGL groups. See LVGL documentation for more info.

LVGL API usage

Every LVGL calls must be protected with these lock/unlock commands:

	/* Wait for the other task done the screen operation */
    lvgl_port_lock(0);
    ...
    lv_obj_t * screen = lv_disp_get_scr_act(disp_handle);
    lv_obj_t * obj = lv_label_create(screen);
    ...
    /* Screen operation done -> release for the other task */
    lvgl_port_unlock();

Rotating screen

LVGL port supports rotation of the display. You can select whether you'd like software rotation or hardware rotation. Software rotation requires no additional logic in your flush_cb callback.

Rotation mode can be selected in the lvgl_port_display_cfg_t structure.

    const lvgl_port_display_cfg_t disp_cfg = {
        ...
        .flags = {
            ...
            .sw_rotate = true / false, // true: software; false: hardware
        }
    }

Display rotation can be changed at runtime.

    lv_disp_set_rotation(disp_handle, LV_DISP_ROT_90);

Note: During the hardware rotating, the component call esp_lcd API. When using software rotation, you cannot use neither direct_mode nor full_refresh in the driver. See LVGL documentation for more info.

Using PSRAM canvas

If the SRAM is insufficient, you can use the PSRAM as a canvas and use a small trans_buffer to carry it, this makes drawing more efficient.

    const lvgl_port_display_cfg_t disp_cfg = {
        ...
        .buffer_size = DISP_WIDTH * DISP_HEIGHT, // in PSRAM, not DMA-capable
        .trans_size = size, // in SRAM, DMA-capable
        .flags = {
            .buff_spiram = true,
            .buff_dma = false,
            ...
        }
    }

Performance

Key feature of every graphical application is performance. Recommended settings for improving LCD performance is described in a separate document here.