MIPI DSI Interfaced LCD

1. Create a DSI bus, it will initialize the DPHY as well.

   esp_lcd_dsi_bus_handle_t mipi_dsi_bus = NULL;
   esp_lcd_dsi_bus_config_t bus_config = {
       .bus_id = 0, // index from 0, specify the DSI host to use
       .num_data_lanes = 2, // Number of data lanes to use, can't set a value that exceeds the chip's capability
       .phy_clk_src = MIPI_DSI_PHY_CLK_SRC_DEFAULT, // Clock source for the DPHY
       .lane_bit_rate_mbps = EXAMPLE_MIPI_DSI_LANE_BITRATE_MBPS, // Bit rate of the data lanes, in Mbps
   };
   ESP_ERROR_CHECK(esp_lcd_new_dsi_bus(&bus_config, &mipi_dsi_bus));
   

2. Derive the DBI interface from the DSI bus. The DBI interface mostly is used as the control IO layer in the esp_lcd component. This interface provides the functions to read/write the configuration registers inside the LCD device. In this step, you need to provide the following information:

   • esp_lcd_dbi_io_config_t::virtual_channel: The virtual channel number to use. The virtual channel is a logical channel that is used to multiplex the data from different sources. If you only have one LCD connected, you can set this to 0.

   • esp_lcd_dbi_io_config_t::lcd_cmd_bits: The bit width of the command that recognized by the LCD controller chip. This is chip specific, you should refer to your LCD spec in advance.

   • esp_lcd_dbi_io_config_t::lcd_param_bits: The bit width of the parameter that recognized by the LCD controller chip. This is chip specific, you should refer to your LCD spec in advance.

   esp_lcd_panel_io_handle_t mipi_dbi_io = NULL;
   esp_lcd_dbi_io_config_t dbi_config = {
       .virtual_channel = 0,
       .lcd_cmd_bits = 8,   // according to the LCD spec
       .lcd_param_bits = 8, // according to the LCD spec
   };
   ESP_ERROR_CHECK(esp_lcd_new_panel_io_dbi(mipi_dsi_bus, &dbi_config, &mipi_dbi_io));
   

3. Install the LCD controller driver. The LCD controller driver is responsible for sending the commands and parameters to the LCD controller chip. In this step, you need to specify the MIPI DBI IO handle that allocated in the last step, and some panel specific configurations:

   • esp_lcd_panel_dev_config_t::bits_per_pixel sets the bit width of each pixel. The LCD driver uses this value to calculate the number of bytes to send to the LCD controller chip.

   • esp_lcd_panel_dev_config_t::reset_gpio_num sets the GPIO number of the reset pin. If the LCD controller chip does not have a reset pin, you can set this value to -1.

   • esp_lcd_panel_dev_config_t::rgb_ele_order set the RGB element order of the pixel data, it can be RGB or BGR.

   esp_lcd_panel_handle_t ili9881c_ctrl_panel = NULL;
   esp_lcd_panel_dev_config_t lcd_dev_config = {
       .bits_per_pixel = 24, // MIPI LCD usually uses 24bit (i.e., RGB888) per pixel
       .rgb_ele_order = LCD_RGB_ELEMENT_ORDER_RGB,
       .reset_gpio_num = EXAMPLE_PIN_NUM_LCD_RST,
   };
   ESP_ERROR_CHECK(esp_lcd_new_panel_ili9881c(mipi_dbi_io, &lcd_dev_config, &ili9881c_ctrl_panel));
   

4. With the LCD control panel that returned in the last step, you can reset the LCD device followed by a basic initialization. After that, you can turn on the display.

   ESP_ERROR_CHECK(esp_lcd_panel_reset(ili9881c_ctrl_panel));
   ESP_ERROR_CHECK(esp_lcd_panel_init(ili9881c_ctrl_panel));
   ESP_ERROR_CHECK(esp_lcd_panel_disp_on_off(ili9881c_ctrl_panel, true));
   

5. However, you still can't send pixel data to the MIPI LCD with the control panel, because MIPI LCD has a high resolution and there's no GRAM in the LCD controller. We need to maintain the LCD frame buffer and flush it to the LCD via the MIPI DSI DPI interface. To allocate a DPI data panel, you need to provide many essential parameters, including the DPI clock frequency, the pixel format, the video timing, and so on.

   • esp_lcd_dpi_panel_config_t::virtual_channel Like the DBI interface, we also need to set the virtual channel for the DPI interface. If you only have one LCD connected, you can set this to 0.

   • esp_lcd_dpi_panel_config_t::dpi_clk_src sets the clock source for the DPI interface. The available clock sources are listed in mipi_dsi_dpi_clock_source_t.

   • esp_lcd_dpi_panel_config_t::dpi_clock_freq_mhz sets the DPI clock frequency in MHz. Higher pixel clock frequency results in higher refresh rate, but may cause flickering if the DMA bandwidth is not sufficient or the LCD controller chip does not support high pixel clock frequency.

   • esp_lcd_dpi_panel_config_t::in_color_format sets the pixel format of the input pixel data. The available pixel formats are listed in lcd_color_format_t. We usually use RGB888 for MIPI LCD to get the best color depth.

   • esp_lcd_dpi_panel_config_t::video_timing sets the LCD panel specific timing parameters. All required parameters are listed in the esp_lcd_video_timing_t, including the LCD resolution and blanking porches. Please fill them according to the datasheet of your LCD.

   • esp_lcd_dpi_panel_config_t::extra_dpi_panel_flags::use_dma2d sets whether to use the 2D DMA peripheral to copy the user data to the frame buffer, asynchronously.

   esp_lcd_panel_handle_t mipi_dpi_panel = NULL;
   esp_lcd_dpi_panel_config_t dpi_config = {
       .virtual_channel = 0,
       .dpi_clk_src = MIPI_DSI_DPI_CLK_SRC_DEFAULT,
       .dpi_clock_freq_mhz = 1 * 1000,
       .in_color_format = LCD_COLOR_FMT_RGB888,
       .video_timing = {
           .h_size = EXAMPLE_MIPI_DSI_LCD_H_RES,
           .v_size = EXAMPLE_MIPI_DSI_LCD_V_RES,
           .hsync_back_porch = EXAMPLE_MIPI_DSI_LCD_HBP,
           .hsync_pulse_width = EXAMPLE_MIPI_DSI_LCD_HSYNC,
           .hsync_front_porch = EXAMPLE_MIPI_DSI_LCD_HFP,
           .vsync_back_porch = EXAMPLE_MIPI_DSI_LCD_VBP,
           .vsync_pulse_width = EXAMPLE_MIPI_DSI_LCD_VSYNC,
           .vsync_front_porch = EXAMPLE_MIPI_DSI_LCD_VFP,
       },
       .flags.use_dma2d = true,
   };
   ESP_ERROR_CHECK(esp_lcd_new_panel_dpi(mipi_dsi_bus, &dpi_config, &mipi_dpi_panel));
   ESP_ERROR_CHECK(esp_lcd_panel_init(mipi_dpi_panel));
   

API Reference

Header File

• components/esp_lcd/dsi/include/esp_lcd_mipi_dsi.h

• This header file can be included with:

  #include "esp_lcd_mipi_dsi.h"
  

• This header file is a part of the API provided by the esp_lcd component. To declare that your component depends on esp_lcd, add the following to your CMakeLists.txt:

  REQUIRES esp_lcd
  

  or

  PRIV_REQUIRES esp_lcd
  

Functions

esp_err_t esp_lcd_new_dsi_bus(const esp_lcd_dsi_bus_config_t *bus_config, esp_lcd_dsi_bus_handle_t *ret_bus)

Create MIPI DSI bus handle.

Parameters

• bus_config -- [in] Bus configuration

• ret_bus -- [out] Returned bus handle

Returns

• ESP_OK: Create MIPI DSI bus successfully

• ESP_ERR_INVALID_ARG: Create MIPI DSI bus failed because of invalid argument

• ESP_ERR_NO_MEM: Create MIPI DSI bus failed because of out of memory

• ESP_ERR_NOT_FOUND: Create MIPI DSI bus failed because no more free DSI hardware instance

• ESP_FAIL: Create MIPI DSI bus failed because of other error

esp_err_t esp_lcd_del_dsi_bus(esp_lcd_dsi_bus_handle_t bus)

Destroy MIPI DSI bus handle.

Parameters

bus -- [in] MIPI DSI bus handle, returned from esp_lcd_new_dsi_bus

Returns

• ESP_OK: Destroy MIPI DSI bus successfully

• ESP_ERR_INVALID_ARG: Destroy MIPI DSI bus failed because of invalid argument

• ESP_FAIL: Destroy MIPI DSI bus failed because of other error

esp_err_t esp_lcd_new_panel_io_dbi(esp_lcd_dsi_bus_handle_t bus, const esp_lcd_dbi_io_config_t *io_config, esp_lcd_panel_io_handle_t *ret_io)

Create LCD panel IO, for MIPI DSI DBI interface.

Note

Although we call it "DBI", internally the driver is using a co-called "generic" interface for transmitting/receiving LCD commands and parameters.

Parameters

• bus -- [in] MIPI DSI bus handle, returned from esp_lcd_new_dsi_bus

• io_config -- [in] IO configuration

• ret_io -- [out] Returned panel IO handle

Returns

• ESP_OK: Create MIPI DSI command IO successfully

• ESP_ERR_INVALID_ARG: Create MIPI DSI command IO failed because of invalid argument

• ESP_ERR_NO_MEM: Create MIPI DSI command IO failed because of out of memory

• ESP_FAIL: Create MIPI DSI command IO failed because of other error

esp_err_t esp_lcd_new_panel_dpi(esp_lcd_dsi_bus_handle_t bus, const esp_lcd_dpi_panel_config_t *panel_config, esp_lcd_panel_handle_t *ret_panel)

Create LCD panel for MIPI DSI DPI interface.

Parameters

• bus -- [in] MIPI DSI bus handle, returned from esp_lcd_new_dsi_bus

• panel_config -- [in] DSI data panel configuration

• ret_panel -- [out] Returned LCD panel handle

Returns

• ESP_OK: Create MIPI DSI data panel successfully

• ESP_ERR_INVALID_ARG: Create MIPI DSI data panel failed because of invalid argument

• ESP_ERR_NO_MEM: Create MIPI DSI data panel failed because of out of memory

• ESP_ERR_NOT_SUPPORTED: Create MIPI DSI data panel failed because of unsupported feature

• ESP_FAIL: Create MIPI DSI data panel failed because of other error

esp_err_t esp_lcd_dpi_panel_get_frame_buffer(esp_lcd_panel_handle_t dpi_panel, uint32_t fb_num, void **fb0, ...)

Get the address of the frame buffer(s) that allocated by the driver.

Parameters

• dpi_panel -- [in] MIPI DPI panel handle, returned from esp_lcd_new_panel_dpi()

• fb_num -- [in] Number of frame buffer(s) to get. This value must be the same as the number of the followed parameters.

• fb0 -- [out] Address of the frame buffer 0 (first frame buffer)

• ... -- [out] List of other frame buffers if any

Returns

• ESP_ERR_INVALID_ARG: Get frame buffer address failed because of invalid argument

• ESP_OK: Get frame buffer address successfully

esp_err_t esp_lcd_dpi_panel_set_pattern(esp_lcd_panel_handle_t dpi_panel, mipi_dsi_pattern_type_t pattern)

Set pre-defined pattern to the screen for testing or debugging purpose.

Parameters

• dpi_panel -- [in] MIPI DPI panel handle, returned from esp_lcd_new_panel_dpi()

• pattern -- [in] Pattern type

Returns

• ESP_OK: Set pattern successfully

• ESP_ERR_INVALID_ARG: Set pattern failed because of invalid argument

• ESP_FAIL: Set pattern failed because of other error

esp_err_t esp_lcd_dpi_panel_set_color_conversion(esp_lcd_panel_handle_t dpi_panel, const esp_lcd_color_conv_config_t *config)

Set color conversion configuration for DPI panel.

Parameters

• dpi_panel -- [in] MIPI DPI panel handle, returned from esp_lcd_new_panel_dpi()

• config -- [in] Color conversion configuration

Returns

• ESP_OK: Set color conversion configuration successfully

• ESP_ERR_INVALID_ARG: Set color conversion configuration failed because of invalid argument

• ESP_FAIL: Set color conversion configuration failed because of other error

esp_err_t esp_lcd_dpi_panel_register_event_callbacks(esp_lcd_panel_handle_t dpi_panel, const esp_lcd_dpi_panel_event_callbacks_t *cbs, void *user_ctx)

Register LCD DPI panel callbacks.

Parameters

• dpi_panel -- [in] LCD DPI panel handle, which is returned from esp_lcd_new_panel_dpi()

• cbs -- [in] structure with all LCD panel callbacks

• user_ctx -- [in] User private data, passed directly to callback's user_ctx

Returns

• ESP_ERR_INVALID_ARG: Register callbacks failed because of invalid argument

• ESP_OK: Register callbacks successfully

Structures

struct esp_lcd_dsi_bus_config_t

MIPI DSI bus configuration structure.

Public Members

int bus_id

Select which DSI controller, index from 0

uint8_t num_data_lanes

Number of data lanes, if set to 0, the driver will fallback to use maximum number of lanes

mipi_dsi_phy_clock_source_t phy_clk_src

MIPI DSI PHY clock source

uint32_t lane_bit_rate_mbps

Lane bit rate in Mbps

struct esp_lcd_dbi_io_config_t

Panel IO configuration structure, for MIPI DSI command interface.

Public Members

uint8_t virtual_channel

Virtual channel ID, index from 0

int lcd_cmd_bits

Bit-width of LCD command

int lcd_param_bits

Bit-width of LCD parameter

struct esp_lcd_dpi_panel_config_t

MIPI DSI DPI panel configuration structure.

Public Members

uint8_t virtual_channel

Virtual channel ID, index from 0

mipi_dsi_dpi_clock_source_t dpi_clk_src

MIPI DSI DPI clock source

uint32_t dpi_clock_freq_mhz

DPI clock frequency in MHz

lcd_color_rgb_pixel_format_t pixel_format

Pixel format that used by the MIPI LCD device

lcd_color_format_t in_color_format

Format of the input data (color space and pixel format), which is the format stored in the frame buffer

lcd_color_format_t out_color_format

Format of the output data (color space and pixel format), which is the format that the panel can accept

uint8_t num_fbs

Number of screen-sized frame buffers that allocated by the driver By default (set to either 0 or 1) only one frame buffer will be created

esp_lcd_video_timing_t video_timing

Video timing

struct esp_lcd_dpi_panel_config_t::extra_dpi_panel_flags flags

Extra configuration flags

struct extra_dpi_panel_flags

Extra configuration flags for MIPI DSI DPI panel.

Public Members

uint32_t use_dma2d

Use DMA2D to copy user buffer to the frame buffer when necessary

uint32_t disable_lp

Disable low-power for DPI

struct esp_lcd_dpi_panel_event_data_t

Type of LCD DPI panel event data.

struct esp_lcd_dpi_panel_event_callbacks_t

Type of LCD DPI panel callbacks.

Public Members

esp_lcd_dpi_panel_color_trans_done_cb_t on_color_trans_done

Invoked when user's color buffer copied to the internal frame buffer. This is an indicator that the draw buffer can be recycled safely. But doesn't mean the draw buffer finishes the refreshing to the screen.

esp_lcd_dpi_panel_refresh_done_cb_t on_refresh_done

Invoked when the internal frame buffer finishes refreshing to the screen

Type Definitions

typedef struct esp_lcd_dsi_bus_t *esp_lcd_dsi_bus_handle_t

Type of MIPI DSI bus handle

typedef bool (*esp_lcd_dpi_panel_general_cb_t)(esp_lcd_panel_handle_t panel, esp_lcd_dpi_panel_event_data_t *edata, void *user_ctx)

A general function callback prototype for DPI panel driver.

Param panel

[in] LCD panel handle, which is created by factory API like esp_lcd_new_panel_dpi()

Param edata

[in] DPI panel event data, fed by driver

Param user_ctx

[in] User data

Return

Whether a high priority task has been waken up by this function

typedef esp_lcd_dpi_panel_general_cb_t esp_lcd_dpi_panel_color_trans_done_cb_t

Declare the prototype of the function that will be invoked when driver finishes coping user's color buffer to frame buffer.

typedef esp_lcd_dpi_panel_general_cb_t esp_lcd_dpi_panel_refresh_done_cb_t

Declare the prototype of the function that will be invoked when driver finishes refreshing the frame buffer to the screen.

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