Renesas

The HMI-Board development board SDK now comes with LVGL integration for quick evaluation. Simply download the SDK for the supported motherboard and you’ll be on your way to creating your next GUI application in no time. For more information, check out the Software design description.

Creating new project with LVGL

It is recommended to start your project by downloading the HMI-Board SDK example project. It comes fully equipped with LVGL and dave-2d support (if the modules are present), so you won’t need to do any additional integration work.

HW acceleration for Renesas RA6M3 platforms

For RA6M3 platforms, hardware acceleration can be achieved using the dave-2d GPU, depending on the platform used. Each accelerator has its own context, allowing them to be used individually or simultaneously in LVGL’s multithreading mode.

Dave-2d accelerator

LVGL can offload several drawing features to the dave-2d engine, freeing up the CPU for other operations while dave-2d runs. An RTOS is required to block the LVGL drawing thread and switch to another task or suspend the CPU for power savings. Supported draw callbacks can be found in “src/draw/renesas/lv_gpu_d2_ra6m3.c”.

LVGL can offload several drawing features to the dave-2d engine, freeing up the CPU for other operations while dave-2d runs. An RTOS is required to block the LVGL drawing thread and switch to another task or suspend the CPU for power savings. Supported draw callbacks can be found in “src/draw/renesas/lv_gpu_d2_ra6m3.c”.

	ra_2d_draw_ctx->blend = lv_draw_ra6m3_2d_blend;
    ra_2d_draw_ctx->base_draw.draw_img_decoded = lv_port_gpu_img_decoded;
    ra_2d_draw_ctx->base_draw.wait_for_finish = lv_port_gpu_wait;
    ra_2d_draw_ctx->base_draw.draw_letter = lv_draw_gpu_letter;

Features supported:

All operations can be used in conjunction with optional transparency.

  • RGB565 and ARGB8888 color formats

  • Area fill with color

  • BLIT (BLock Image Transfer)

  • Color conversion

  • Rotate and scale

  • Alpha blending

  • Bilinear filtering

  • RTOS integration layer

  • Default RT-Thread code provided

  • Subpixel exact placement

Basic configuration:

  • Select Renesas dave-2d engine in lv_conf.h: Set LV_USE_GPU_RA6M3_G2D to 1

  • Set referenced header file in lv_conf.h: #define LV_GPU_RA6M3_G2D_INCLUDE "hal_data.h"

RT-Thread Example:

#define COLOR_BUFFER  (LV_HOR_RES_MAX * LV_VER_RES_MAX)

static lv_disp_drv_t disp_drv;

/*A static or global variable to store the buffers*/
static lv_color_t buf_1[COLOR_BUFFER];

  • After initializing your peripherals (such as SPI, GPIOs, and LCD) in the lv_port_disp_init() function, you can initialize LVGL using lv_init(). Next, register the frame buffers using lv_disp_draw_buf_init() and create a new display driver using lv_disp_drv_init().

/*Initialize `disp_buf` with the buffer(s). With only one buffer use NULL instead buf_2 */
lv_disp_draw_buf_init(&disp_buf, buf_1, RT_NULL, COLOR_BUFFER);
lv_disp_drv_init(&disp_drv); /*Basic initialization*/

/*Set the resolution of the display*/
disp_drv.hor_res = LV_HOR_RES_MAX;
disp_drv.ver_res = LV_VER_RES_MAX;

/*Set a display buffer*/
disp_drv.draw_buf = &disp_buf;

/*Used to copy the buffer's content to the display*/
disp_drv.flush_cb = disp_flush;

/* Initialize GPU module */
lv_port_gpu_hw_init();

/*Finally register the driver*/
lv_disp_drv_register(&disp_drv);

  • To run LVGL, you’ll need to create a thread. You can find examples of how to do this using RT-Thread in the env_support/rt-thread/lv_rt_thread_port.c file.

static void lvgl_thread_entry(void *parameter)
{
#if LV_USE_LOG
    lv_log_register_print_cb(lv_rt_log);
#endif /* LV_USE_LOG */
    lv_init();
    lv_port_disp_init();
    lv_port_indev_init();
    lv_user_gui_init();

    /* handle the tasks of LVGL */
    while(1)
    {
        lv_task_handler();
        rt_thread_mdelay(LV_DISP_DEF_REFR_PERIOD);
    }
}

static int lvgl_thread_init(void)
{
    rt_err_t err;
	
    /* create lvgl thread */
    err = rt_thread_init(&lvgl_thread, "LVGL", lvgl_thread_entry, RT_NULL,
           &lvgl_thread_stack[0], sizeof(lvgl_thread_stack), PKG_LVGL_THREAD_PRIO, 10);
    if(err != RT_EOK)
    {
        LOG_E("Failed to create LVGL thread");
        return -1;
    }
    rt_thread_startup(&lvgl_thread);

    return 0;
}
INIT_ENV_EXPORT(lvgl_thread_init);

  • The last step is to create a function to output the frame buffer to your LCD. The specifics of this function will depend on the features of your MCU. Here’s an example for a typical MCU interface: my_flush_cb.

static void my_flush_cb(lv_disp_drv_t *disp_drv, const lv_area_t *area, lv_color_t *color_p)
{
#ifdef PKG_USING_ILI9341
    lcd_fill_array_spi(area->x1, area->y1, area->x2, area->y2, color_p);
#elif LV_USE_GPU_RA6M3_G2D
    lv_port_gpu_blit(area->x1, area->y1, color_p, area);
#else
    ......
#endif
    lv_disp_flush_ready(disp_drv);
}