ESP32 with ILI9341 flickering and random lines with dark colors

How-to
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1

Hello,

I’m having problems with my LVGL library implementation on an ESP32 when using dark colors or tones. I’ve also noticed it slightly with light colors, and it’s not a display or hardware issue.

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As you can see in the image, random lines begin to appear as the color gets darker. Additionally, there’s a constant flickering that increases in frequency when I increase the ESP32’s clock speed from 160MHz to 240MHz (leading me to believe it’s a configuration or software issue).

This is my code for the display initialization configuration:

static void spi_display_init(void)
{
ESP_LOGI(TAG, “SPI Display: SPI2_HOST, DMA”);
spi_bus_config_t buscfg = {
.mosi_io_num = PIN_LCD_MOSI,
.miso_io_num = PIN_LCD_MISO,
.sclk_io_num = PIN_LCD_CLK,
//.max_transfer_sz = LCD_H_RES * LCD_V_RES * 2 + 8,
.max_transfer_sz = LCD_H_RES * LCD_V_RES * sizeof(uint8_t) * 3,
.flags = SPICOMMON_BUSFLAG_MASTER,
.intr_flags = ESP_INTR_FLAG_IRAM
};
ESP_ERROR_CHECK(spi_bus_initialize(LCD_HOST, &buscfg, SPI_DMA_CH_AUTO));
}

static void lcd_ili9341_init(void)
{
ESP_LOGI(TAG, “ILI9341 init”);
esp_lcd_panel_io_handle_t io_handle = NULL;
esp_lcd_panel_io_spi_config_t io_config = {
.dc_gpio_num = PIN_LCD_DC,
.cs_gpio_num = PIN_LCD_CS,
.pclk_hz = 40 * 1000 * 1000,
.lcd_cmd_bits = 8,
.lcd_param_bits = 8,
.spi_mode = 3,
.trans_queue_depth = 10,
.on_color_trans_done = lcd_flush_ready_cb,
.user_ctx = &disp_drv,
};
ESP_ERROR_CHECK(esp_lcd_new_panel_io_spi((esp_lcd_spi_bus_handle_t)LCD_HOST, &io_config, &io_handle));

esp_lcd_panel_dev_config_t panel_config = {
    .reset_gpio_num = PIN_LCD_RST,
    .rgb_endian = LCD_RGB_ENDIAN_BGR,   // Cambiar a BGR si los colores están invertidos
    .bits_per_pixel = 16,
};
ESP_ERROR_CHECK(esp_lcd_new_panel_ili9341(io_handle, &panel_config, &panel_handle));

ESP_ERROR_CHECK(esp_lcd_panel_reset(panel_handle));
ESP_ERROR_CHECK(esp_lcd_panel_init(panel_handle));

// --- CORRECCIÓN DE ORIENTACIÓN: espejo horizontal ---
bool swap_xy = false;
bool mirror_x = false;
bool mirror_y = false;

#if DISPLAY_ROTATION == 0
swap_xy = false; mirror_x = true; mirror_y = false; // 0°
#elif DISPLAY_ROTATION == 1
swap_xy = true; mirror_x = false; mirror_y = false; // 90°
#elif DISPLAY_ROTATION == 2
swap_xy = false; mirror_x = false; mirror_y = true; // 180°
#elif DISPLAY_ROTATION == 3
swap_xy = true; mirror_x = true; mirror_y = true; // 270°
#endif

ESP_ERROR_CHECK(esp_lcd_panel_swap_xy(panel_handle, swap_xy));
ESP_ERROR_CHECK(esp_lcd_panel_mirror(panel_handle, mirror_x, mirror_y));

ESP_ERROR_CHECK(esp_lcd_panel_disp_on_off(panel_handle, true));

}