esp_lcd driver for RA8876/LT768x based displays

This component provides an implementation of the RA8876/LT768x LCD controller using the esp_lcd component APIs. Both of these chips are functionally identical and can be used interchangeably.

LCD controller	Communication interface	Component name	Link to datasheet
RA8876/LT768x	Intel 8080	esp_lcd_ra8876	Specification

Note on supported communication interfaces

When using the Intel 8080 (Parallel) interface the 16-bit color depth mode should be used. This uses RGB565 format data.

Using this component in your project

This package can be added to your project as follows:

dependencies:
  esp_lcd_ra8876:
    git: https://github.com/danmeuk/esp_lcd_ra8876.git

For more information on the usage of the idf_component.yml file please refer to Espressif's documentation.

Supported platforms

Due to the i80 nature of the interface, this requires ESP32-S3 or higher. Older ESP32 chips do not have hardware support for i80 interfaces.

Testing

This has been tested against a BuyDisplay.com ER-TFTM070-6 panel in 16-bit i80 mode at 12MHz. (note: at slower clock speeds, screen corruption was observed)

Example code

This assumes you have pulled the RD pin high either in software or on your PCB. If you don't do this, you will experience trouble.

This defaults to a 12MHz speed as I experience screen corruption at slower speeds.

To save some precious ESP32 pins, you can tie the CS pin to GND permanently and set LCD_CS to GPIO_NUM_NC.

This code will not work on its own, you need to configure other things such as LVGL and buffers etc. It is provided for guidance only.

/* create i80 bus */
esp_lcd_i80_bus_handle_t i80_bus = NULL;
esp_lcd_i80_bus_config_t bus_config = {
	.clk_src = LCD_CLK_SRC_DEFAULT,
	.dc_gpio_num = LCD_DC,
	.wr_gpio_num = LCD_WR,
	.data_gpio_nums = {
		LCD_D0, LCD_D1, LCD_D2, LCD_D3, LCD_D4, LCD_D5, LCD_D6, LCD_D7,
		LCD_D8, LCD_D9, LCD_D10, LCD_D11, LCD_D12, LCD_D13, LCD_D14, LCD_D15
	},
	.bus_width = 16,
	.psram_trans_align = 64,
	.sram_trans_align = 4,
	.max_transfer_bytes = 1024 * 10 * sizeof(lv_color_t)
};
esp_lcd_new_i80_bus(&bus_config, &i80_bus);
esp_lcd_panel_io_handle_t io_handle = NULL;
esp_lcd_panel_io_i80_config_t io_config = {
	.cs_gpio_num = LCD_CS,
	.pclk_hz = (12 * 1000 * 1000),
	.trans_queue_depth = 32,
	.dc_levels = {
		.dc_idle_level = 0,
		.dc_cmd_level = 0,
		.dc_dummy_level = 0,
		.dc_data_level = 1,
	},
	.flags = {
		.swap_color_bytes = 0,
		.pclk_idle_low = 0,
	},
	.on_color_trans_done = _notify_lvgl_flush_ready,
	.user_ctx = &disp_drv,
	.lcd_cmd_bits = 16,
	.lcd_param_bits = 8,
};
esp_lcd_new_panel_io_i80(i80_bus, &io_config, &io_handle);

/* configure RA8876/LT7683 panel */
const esp_lcd_panel_ra8876_config_t vendor_config = {
	.lcd_width = 1024,
	.lcd_height = 600,
	.mcu_bit_interface = 16,
};
esp_lcd_panel_dev_config_t panel_config = {
	.reset_gpio_num = LCD_RST,
	.color_space = ESP_LCD_COLOR_SPACE_RGB,
	.bits_per_pixel = 16,
	.vendor_config = (void*)&vendor_config,
};
esp_lcd_new_panel_ra8876(io_handle, &panel_config, &lcd_panel_handle);
esp_lcd_panel_init(lcd_panel_handle);
esp_lcd_panel_disp_on_off(lcd_panel_handle, true);