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MIPI Display Bus Interface (DBI)

The MIPI DBI driver class implements support for MIPI DBI compliant display controllers.

MIPI DBI defines 3 interface types:

  • Type A: Motorola 6800 parallel bus

  • Type B: Intel 8080 parallel bus

  • Type C: SPI Type serial bit bus with 3 options:

    1. 9 write clocks per byte, final bit is command/data selection bit

    2. Same as above, but 16 write clocks per byte

    3. 8 write clocks per byte. Command/data selected via GPIO pin

Currently, the API only supports Type C controllers, options 1 and 3.

API Reference

group mipi_dbi_interface

MIPI-DBI driver APIs.

Since

3.6

Version

0.1.0

Defines

MIPI_DBI_SPI_CONFIG_DT(node_id, operation_, delay_)

initialize a MIPI DBI SPI configuration struct from devicetree

This helper allows drivers to initialize a MIPI DBI SPI configuration structure using devicetree.

Parameters:

  • node_id – Devicetree node identifier for the MIPI DBI device whose struct spi_config to create an initializer for

  • operation_ – the desired operation field in the struct spi_config

  • delay_ – the desired delay field in the struct spi_config’s spi_cs_control, if there is one

MIPI_DBI_SPI_CONFIG_DT_INST(inst, operation_, delay_)

Initialize a MIPI DBI SPI configuration from devicetree instance.

This helper initializes a MIPI DBI SPI configuration from a devicetree instance. It is equivalent to MIPI_DBI_SPI_CONFIG_DT(DT_DRV_INST(inst))

Parameters:

  • inst – Instance number to initialize configuration from

  • operation_ – the desired operation field in the struct spi_config

  • delay_ – the desired delay field in the struct spi_config’s spi_cs_control, if there is one

MIPI_DBI_CONFIG_DT(node_id, operation_, delay_)

Initialize a MIPI DBI configuration from devicetree.

This helper allows drivers to initialize a MIPI DBI configuration structure from devicetree. It sets the MIPI DBI mode, as well as configuration fields in the SPI configuration structure

Parameters:

  • node_id – Devicetree node identifier for the MIPI DBI device to initialize

  • operation_ – the desired operation field in the struct spi_config

  • delay_ – the desired delay field in the struct spi_config’s spi_cs_control, if there is one

MIPI_DBI_CONFIG_DT_INST(inst, operation_, delay_)

Initialize a MIPI DBI configuration from device instance.

Equivalent to MIPI_DBI_CONFIG_DT(DT_DRV_INST(inst), operation_, delay_)

Parameters:

  • inst – Instance of the device to initialize a MIPI DBI configuration for

  • operation_ – the desired operation field in the struct spi_config

  • delay_ – the desired delay field in the struct spi_config’s spi_cs_control, if there is one

MIPI_DBI_MODE_SPI_3WIRE

SPI 3 wire (Type C1).

Uses 9 write clocks to send a byte of data. The bit sent on the 9th clock indicates whether the byte is a command or data byte

      .---.   .---.   .---.   .---.   .---.   .---.   .---.   .---.
SCK  -'   '---'   '---'   '---'   '---'   '---'   '---'   '---'   '---

     -.---.---.---.---.---.---.---.---.---.---.---.---.---.---.---.
DOUT  |D/C| D7| D6| D5| D4| D3| D2| D1| D0|D/C| D7| D6| D5| D4|...|
     -'---'---'---'---'---'---'---'---'---'---'---'---'---'---'---'
      | Word 1                            | Word n

     -.                                                              .--
CS    '-----------------------------------------------------------'
MIPI_DBI_MODE_SPI_4WIRE

SPI 4 wire (Type C3).

Uses 8 write clocks to send a byte of data. an additional C/D pin will be use to indicate whether the byte is a command or data byte 

      .---.   .---.   .---.   .---.   .---.   .---.   .---.   .---.
SCK  -'   '---'   '---'   '---'   '---'   '---'   '---'   '---'   '---

     -.---.---.---.---.---.---.---.---.---.---.---.---.---.---.---.---.
DOUT  | D7| D6| D5| D4| D3| D2| D1| D0| D7| D6| D5| D4| D3| D2| D1| D0|
     -'---'---'---'---'---'---'---'---'---'---'---'---'---'---'---'---'
      | Word 1                        | Word n

     -.                                                                  .--
CS    '---------------------------------------------------------------'

     -.-------------------------------.-------------------------------.-
CD    |             D/C               |             D/C               |
     -'-------------------------------'-------------------------------'-

MIPI_DBI_MODE_6800_BUS_16_BIT

Parallel Bus protocol for MIPI DBI Type A based on Motorola 6800 bus. 

         -.   .--------.      .------------------------
CS        '---'        '---'

         -------------------------------------------
RESX

              .--------------------------------
D/CX     ----------'


R/WX     -------------------------------------------

         -------------------------------------------
E

          .--------.   .--------------------------.
D[15:0]/ -| COMMAND|---|  DATA                    |
D[8:0]/   '--------'   '--------------------------'
D[7:0]
Please refer to the MIPI DBI specification for a detailed cycle diagram.

MIPI_DBI_MODE_6800_BUS_9_BIT
MIPI_DBI_MODE_6800_BUS_8_BIT
MIPI_DBI_MODE_8080_BUS_16_BIT

Parallel Bus protocol for MIPI DBI Type B based on Intel 8080 bus. 

         -.                                  .-
CS        '---------------------------------------'

         -------------------------------------------
RESX

         --.              .----------------------------
D/CX       '-----------'

         ---.   .--------.   .----------------------
WRX         '---'   '---'

         -------------------------------------------
RDX

            .--------.   .--------------------------.
D[15:0]/ ---| COMMAND|---|  DATA                    |
D[8:0]/     '--------'   '--------------------------'
D[7:0]
Please refer to the MIPI DBI specification for a detailed cycle diagram.

MIPI_DBI_MODE_8080_BUS_9_BIT
MIPI_DBI_MODE_8080_BUS_8_BIT

Functions

static inline int mipi_dbi_command_write(const struct device *dev, const struct mipi_dbi_config *config, uint8_t cmd, const uint8_t *data, size_t len)

Write a command to the display controller.

Writes a command, along with an optional data buffer to the display. If data buffer and buffer length are NULL and 0 respectively, then only a command will be sent. Note that if the SPI configuration passed to this function locks the SPI bus, it is the caller’s responsibility to release it with mipi_dbi_release()

Parameters:

  • dev – mipi dbi controller

  • config – MIPI DBI configuration

  • cmd – command to write to display controller

  • data – optional data buffer to write after command

  • len – size of data buffer in bytes. Set to 0 to skip sending data.

Return values:

  • 0 – command write succeeded

  • -EIO – I/O error

  • -ETIMEDOUT – transfer timed out

  • -EBUSY – controller is busy

  • -ENOSYS – not implemented

static inline int mipi_dbi_command_read(const struct device *dev, const struct mipi_dbi_config *config, uint8_t *cmds, size_t num_cmd, uint8_t *response, size_t len)

Read a command response from the display controller.

Reads a command response from the display controller.

Parameters:

  • dev – mipi dbi controller

  • config – MIPI DBI configuration

  • cmds – array of one byte commands to send to display controller

  • num_cmd – number of commands to write to display controller

  • response – response buffer, filled with display controller response

  • len – size of response buffer in bytes.

Return values:

  • 0 – command read succeeded

  • -EIO – I/O error

  • -ETIMEDOUT – transfer timed out

  • -EBUSY – controller is busy

  • -ENOSYS – not implemented

static inline int mipi_dbi_write_display(const struct device *dev, const struct mipi_dbi_config *config, const uint8_t *framebuf, struct display_buffer_descriptor *desc, enum display_pixel_format pixfmt)

Write a display buffer to the display controller.

Writes a display buffer to the controller. If the controller requires a “Write memory” command before writing display data, this should be sent with mipi_dbi_command_write

Parameters:

  • dev – mipi dbi controller

  • config – MIPI DBI configuration

  • framebuf – framebuffer to write to display

  • desc – descriptor of framebuffer to write. Note that the pitch must be equal to width. “buf_size” field determines how many bytes will be written.

  • pixfmt – pixel format of framebuffer data

Return values:

  • 0 – buffer write succeeded.

  • -EIO – I/O error

  • -ETIMEDOUT – transfer timed out

  • -EBUSY – controller is busy

  • -ENOSYS – not implemented

static inline int mipi_dbi_reset(const struct device *dev, uint32_t delay)

Resets attached display controller.

Resets the attached display controller.

Parameters:

  • dev – mipi dbi controller

  • delay – duration to set reset signal for, in milliseconds

Return values:

  • 0 – reset succeeded

  • -EIO – I/O error

  • -ENOSYS – not implemented

  • -ENOTSUP – not supported

static inline int mipi_dbi_release(const struct device *dev, const struct mipi_dbi_config *config)

Releases a locked MIPI DBI device.

Releases a lock on a MIPI DBI device and/or the device’s CS line if and only if the given config parameter was the last one to be used in any of the above functions, and if it has the SPI_LOCK_ON bit set and/or the SPI_HOLD_ON_CS bit set into its operation bits field. This lock functions exactly like the SPI lock, and can be used if the caller needs to keep CS asserted for multiple transactions, or the MIPI DBI device locked.

Parameters:

  • dev – mipi dbi controller

  • config – MIPI DBI configuration

Return values:

  • 0 – reset succeeded

  • -EIO – I/O error

  • -ENOSYS – not implemented

  • -ENOTSUP – not supported

struct mipi_dbi_config
#include <mipi_dbi.h>

MIPI DBI controller configuration.

Configuration for MIPI DBI controller write

Public Members

uint8_t mode

MIPI DBI mode (SPI 3 wire or 4 wire)

struct spi_config config

SPI configuration.

struct mipi_dbi_driver_api
#include <mipi_dbi.h>

MIPI-DBI host driver API.