Why is the image on my LCD skewed?

[vritzka]

Hi,

I am running a 7-inch RGB Display with this IDF example --> (https://github.com/espressif/esp-idf/tr ... /rgb_panel)

Its a 18 / 24 bit RGB Display. But its being run with 16 Bit.

Its working well, Except that the image is slightly skewed.

All circles are egg-shaped when they should be perfectly round.

Its difficult to show, but here are some images.

IMG_7033.jpg (76.6 KiB) Viewed 1883 times

IMG_7034.jpg (83.74 KiB) Viewed 1883 times

Perhaps it has something to do with the LCD timings? I tried changing them in many ways to no avail.

Currently my LCD is created with these timings:

Code: Select all

  esp_lcd_rgb_panel_config_t panel_config = {
        .data_width = 16, // RGB565 in parallel mode, thus 16bit in width
        .bits_per_pixel = 16,
        .psram_trans_align = 64,
        .clk_src = LCD_CLK_SRC_DEFAULT,
        .disp_gpio_num = EXAMPLE_PIN_NUM_DISP_EN,
        .pclk_gpio_num = EXAMPLE_PIN_NUM_PCLK,
        .vsync_gpio_num = EXAMPLE_PIN_NUM_VSYNC,
        .hsync_gpio_num = EXAMPLE_PIN_NUM_HSYNC,
        .de_gpio_num = EXAMPLE_PIN_NUM_DE,
        .data_gpio_nums = {
            EXAMPLE_PIN_NUM_DATA0,
		(...)
            EXAMPLE_PIN_NUM_DATA15,
        },
        .timings = {
            .pclk_hz = EXAMPLE_LCD_PIXEL_CLOCK_HZ, //(18 * 1000 * 1000)
            .h_res = EXAMPLE_LCD_H_RES, //800
            .v_res = EXAMPLE_LCD_V_RES, //480
            // The following parameters should refer to LCD spec
            .hsync_back_porch = 46, 
            .hsync_front_porch = 210,
            .hsync_pulse_width = 1, 
            .vsync_back_porch = 23,
            .vsync_front_porch = 147,
            .vsync_pulse_width = 1,
            .flags.pclk_active_neg = true,
        },
        .flags.fb_in_psram = true, // allocate frame buffer in PSRAM

The Datasheet says:

IMG_7035.jpg (274.48 KiB) Viewed 1883 times

[ESP_Sprite]

Are you sure the pixels on the display itself are square? (As in, can you link the datasheet, or calculate the H and W of a pixel yourself?)

[vritzka]

Hi,

the Dot Pitch is 0.0642 (w) x 0.1790(h) mm

So the pixels are not square if I understand correctly.

I also attached the Datasheet. If you have a moment, would you please have a look?