Stop random flickering vertical lines, ESP32 CYD, IL9341, esp-idf

How to
1

I try to port my project (GitHub - 0xPIT/ESPGrind at cyd-2432S024C) to the IL9341 of a capacitive CYD (2432S024C). My UI is 99% made in Squareline, I use esp-idf, including their display driver.

While everything seems to render and work mostly normally, I get randomly flickering vertical lines, but only on some of the screens and only on a part of the screen – see screenshot.
Please note that this code works fine on a waveshare display and on the ESP-BOX.

The main screen works normally, but has some single lines flickering while I increment/decrement a spinbox via a timer.

I’ve tried different SPI speeds, but that does not change anything.

Can anyone help me to get a clean display?
The BSP code is here.

Thanks!

Screenshot 2025-01-16 at 09.22.07
Screenshot 2025-01-16 at 09.22.072134×1210 453 KB

2

Hi, Since you mentioned it works fine on other displays, it’s likely either a hardware issue with this specific display module or a compatibility issue with its timing requirements.

3

Here are some suggestions:

  1. SPI Configuration:
const esp_lcd_panel_io_spi_config_t io_config = {                                             
    .dc_gpio_num = BSP_LCD_DC,
    .cs_gpio_num = BSP_LCD_CS,
    .pclk_hz = BSP_LCD_PIXEL_CLOCK_HZ,  // Try reducing this
    .lcd_cmd_bits = BSP_LCD_CMD_BITS,
    .lcd_param_bits = BSP_LCD_PARAM_BITS,
    .spi_mode = 0,  // Try mode 3 (CPOL=1, CPHA=1)
    .trans_queue_depth = 10
};
  1. Buffer Configuration:
const bsp_display_config_t bsp_disp_cfg = {
    .max_transfer_sz = (BSP_LCD_H_RES * BSP_LCD_DRAW_BUF_HEIGHT) * sizeof(uint16_t),
};

Try these modifications:

  1. LCD Panel Timing:

    • Reduce the pixel clock frequency (BSP_LCD_PIXEL_CLOCK_HZ)
    • Try different SPI modes (particularly mode 3)

  2. Buffer Management:

    • Enable double buffering if not already enabled:
.double_buffer = 1,
  1. DMA Settings:
    • Ensure DMA channel is properly configured:
.flags = {
    .buff_dma = true,
    .buff_spiram = false,
}
  1. Panel Initialization:
esp_lcd_panel_init(*ret_panel);
// Add these commands after init:
esp_lcd_panel_invert_color(*ret_panel, false);
esp_lcd_panel_swap_xy(*ret_panel, true);

The flickering might be related to timing issues between the ESP32 and the ILI9341. I’d recommend trying these changes one at a time to identify which solves the issue.

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4

Thanks for your reply.
None of your suggestions did any change.

I’ve managed to fix it by using this custom init code instead of what’s in the driver from esp-idf.

FYI, custom init code can be passed using .vendor_config of esp_lcd_panel_dev_config_t, prior calling esp_lcd_new_panel_<panel>() – at least for the ili9341 driver.

1 Like