Driver for the LCD display More...

Detailed Description

Driver for the LCD display

The LCD is a generic display driver for small RGB displays. It communicates with the device either via an

SPI serial interface (if module lcd_spi enabled) or an
MCU 8080 8-/16-bit parallel interface (if module lcd_parallel or module lcd_parallel_16 is enabled).

Usually the device driver is used either for a single display with SPI serial interface or for a display with parallel MCU 8080 8-/16-bit parallel interface. However, the device driver can also be used simultaneously for multiple displays with different interfaces if several of the lcd_spi, lcd_parallel and lcd_parallel_16bit modules are enabled at the same time. In this case, please refer to the notes in lcd_params_t.

The device requires colors to be send in big endian RGB-565 format. The CONFIG_LCD_LE_MODE compile time option can switch this, but only use this when strictly necessary. This option will slow down the driver as it certainly can't use DMA anymore, every short has to be converted before transfer.

Files
file	lcd.h

file	lcd_disp_dev.h
	Definition of the driver for the disp_dev generic interface.

file	lcd_internal.h
	Device driver implementation for the lcd display controller.

Data Structures
struct	lcd_params_t
	Device initialization parameters. More...

struct	lcd_t
	Device descriptor for a lcd. More...

struct	lcd_driver
	LCD driver interface. More...

struct	lcd_ll_par_driver_t
	Low-level MCU 8080 8-/16-bit parallel interface driver. More...

Macros
#define	CONFIG_LCD_LE_MODE
	Convert little endian colors to big endian.

Typedefs
typedef struct lcd_driver	lcd_driver_t
	LCD driver interface.

Enumerations
enum	lcd_if_mode_t { LCD_IF_SPI , LCD_IF_PARALLEL_8BIT , LCD_IF_PARALLEL_16BIT }
	Display interface modi. More...

Low-level MCU 8080 8-/16-bit parallel interface
The low-level MCU 8080 8-/16-bit parallel interface (low-level parallel interface for short) is used when the LCD device is connected via a parallel interface. Either the GPIO-driven low-level parallel interface provided by this LCD driver or a low-level parallel interface implemented by the MCU, such as the STM32 FMC peripheral, can be used. If the MCU provides its own implementation of the low-level parallel interface, it can be used by implementing the following low-level parallel interface driver functions, enabling the `lcd_parallel_ll_mcu` module and defining the lcd_ll_par_driver variable of type lcd_ll_par_driver_t.
const lcd_ll_par_driver_t	lcd_ll_par_driver
	Low-level parallel interface driver instance.

Low-level LCD API
Low-level functions are used to acquire a device, write commands with data to the device, or read data from the device and release it when it is no longer needed. They are usually called by the high-level functions such as lcd_init, lcd_fill, lcd_pixmap, etc., but can also be used by the application to implement low-level operations if needed.
void	lcd_ll_acquire (lcd_t *dev)
	Low-level function to acquire the device.

void	lcd_ll_release (lcd_t *dev)
	Low-level function to release the device.

void	lcd_ll_write_cmd (lcd_t dev, uint8_t cmd, const uint8_t data, size_t len)
	Low-level function to write a command.

void	lcd_ll_read_cmd (lcd_t dev, uint8_t cmd, uint8_t data, size_t len)
	Low-level function for read command.

void	lcd_ll_set_area (lcd_t *dev, uint16_t x1, uint16_t x2, uint16_t y1, uint16_t y2)
	Set the LCD work area.

High-level LCD API
The functions of the high-level LCD API are used by the application. They use the low-level LCD API to implement more complex operations.
int	lcd_init (lcd_t dev, const lcd_params_t params)
	Setup an LCD display device.

void	lcd_fill (lcd_t *dev, uint16_t x1, uint16_t x2, uint16_t y1, uint16_t y2, uint16_t color)
	Fill a rectangular area with a single pixel color.

void	lcd_pixmap (lcd_t dev, uint16_t x1, uint16_t x2, uint16_t y1, uint16_t y2, const uint16_t color)
	Fill a rectangular area with an array of pixels.

void	lcd_write_cmd (lcd_t dev, uint8_t cmd, const uint8_t data, size_t len)
	Raw write command.

void	lcd_read_cmd (lcd_t dev, uint8_t cmd, uint8_t data, size_t len)
	Raw read command.

void	lcd_invert_on (lcd_t *dev)
	Invert the display colors.

void	lcd_invert_off (lcd_t *dev)
	Disable color inversion.

Memory access control bits
#define	LCD_MADCTL_MY 0x80
	Row address order.

#define	LCD_MADCTL_MX 0x40
	Column access order.

#define	LCD_MADCTL_MV 0x20
	Row column exchange.

#define	LCD_MADCTL_ML 0x10
	Vertical refresh order.

#define	LCD_MADCTL_BGR 0x08
	Color selector switch control.

#define	LCD_MADCTL_MH 0x04
	Horizontal refresh direction.

Macro Definition Documentation

◆ CONFIG_LCD_LE_MODE

#define CONFIG_LCD_LE_MODE

Convert little endian colors to big endian.

Compile time switch to change the driver to convert little endian colors to big endian.

Definition at line 69 of file lcd.h.

◆ LCD_MADCTL_BGR

#define LCD_MADCTL_BGR 0x08

Color selector switch control.

Definition at line 80 of file lcd.h.

◆ LCD_MADCTL_MH

#define LCD_MADCTL_MH 0x04

Horizontal refresh direction.

Definition at line 81 of file lcd.h.

◆ LCD_MADCTL_ML

#define LCD_MADCTL_ML 0x10

Vertical refresh order.

Definition at line 79 of file lcd.h.

◆ LCD_MADCTL_MV

#define LCD_MADCTL_MV 0x20

Row column exchange.

Definition at line 78 of file lcd.h.

◆ LCD_MADCTL_MX

#define LCD_MADCTL_MX 0x40

Column access order.

Definition at line 77 of file lcd.h.

◆ LCD_MADCTL_MY

#define LCD_MADCTL_MY 0x80

Row address order.

Definition at line 76 of file lcd.h.

Typedef Documentation

◆ lcd_driver_t

typedef struct lcd_driver lcd_driver_t

LCD driver interface.

This define the functions to access a LCD.

Definition at line 170 of file lcd.h.

Enumeration Type Documentation

◆ lcd_if_mode_t

enum lcd_if_mode_t

Display interface modi.

This enumeration is only needed if the MCU 8080 8-/16-bit interfaces are enabled by lcd_parallel or lcd_parallel_16bit. Otherwise the serial SPI interface is implicitly assumed.

Enumerator
LCD_IF_SPI	SPI serial interface mode.
LCD_IF_PARALLEL_8BIT	MCU 8080 8-bit parallel interface mode.
LCD_IF_PARALLEL_16BIT	MCU 8080 16-bit parallel interface mode.

Definition at line 92 of file lcd.h.

Function Documentation

◆ lcd_fill()

void lcd_fill	(	lcd_t *	dev,
		uint16_t	x1,
		uint16_t	x2,
		uint16_t	y1,
		uint16_t	y2,
		uint16_t	color )

Fill a rectangular area with a single pixel color.

the rectangular area is defined as x1 being the first column of pixels and x2 being the last column of pixels to fill. similar to that, y1 is the first row to fill and y2 is the last row to fill.

Parameters

[in]	dev	device descriptor
[in]	x1	x coordinate of the first corner
[in]	x2	x coordinate of the opposite corner
[in]	y1	y coordinate of the first corner
[in]	y2	y coordinate of the opposite corner
[in]	color	single color to fill the area with

◆ lcd_init()

int lcd_init	(	lcd_t *	dev,
		const lcd_params_t *	params )

Setup an LCD display device.

Parameters

[in]	dev	device descriptor
[in]	params	parameters for device initialization

◆ lcd_invert_off()

void lcd_invert_off ( lcd_t * dev )

Disable color inversion.

Parameters

[in] dev device descriptor

◆ lcd_invert_on()

void lcd_invert_on ( lcd_t * dev )

Invert the display colors.

Parameters

[in] dev device descriptor

◆ lcd_ll_acquire()

void lcd_ll_acquire ( lcd_t * dev )

Low-level function to acquire the device.

Parameters

[out] dev device descriptor

◆ lcd_ll_read_cmd()

void lcd_ll_read_cmd	(	lcd_t *	dev,
		uint8_t	cmd,
		uint8_t *	data,
		size_t	len )

Low-level function for read command.

Note: Very often the SPI MISO signal of the serial interface or the RDX signal of the MCU 8080 parallel interface are not connected to the display. In this case the read command does not provide valid data.

Precondition: The device must have already been acquired with lcd_ll_acquire before this function can be called.; len > 0

Parameters

[in]	dev	device descriptor
[in]	cmd	command
[out]	data	data from the device
[in]	len	length of the returned data

◆ lcd_ll_release()

void lcd_ll_release ( lcd_t * dev )

Low-level function to release the device.

Parameters

[out] dev device descriptor

◆ lcd_ll_set_area()

void lcd_ll_set_area	(	lcd_t *	dev,
		uint16_t	x1,
		uint16_t	x2,
		uint16_t	y1,
		uint16_t	y2 )

Set the LCD work area.

Parameters

[in]	dev	Pointer to the selected driver
[in]	x1	x coordinate of the first corner
[in]	x2	x coordinate of the opposite corner
[in]	y1	y coordinate of the first corner
[in]	y2	y coordinate of the opposite corner

◆ lcd_ll_write_cmd()

void lcd_ll_write_cmd	(	lcd_t *	dev,
		uint8_t	cmd,
		const uint8_t *	data,
		size_t	len )

Low-level function to write a command.

Precondition: The device must have already been acquired with lcd_ll_acquire before this function can be called.

Parameters

[in]	dev	device descriptor
[in]	cmd	command code
[in]	data	command data to the device or NULL for commands without data
[in]	len	length of the command data or 0 for commands without data

◆ lcd_pixmap()

void lcd_pixmap	(	lcd_t *	dev,
		uint16_t	x1,
		uint16_t	x2,
		uint16_t	y1,
		uint16_t	y2,
		const uint16_t *	color )

Fill a rectangular area with an array of pixels.

the rectangular area is defined as x1 being the first column of pixels and x2 being the last column of pixels to fill. similar to that, y1 is the first row to fill and y2 is the last row to fill.

Note: color must have a length equal to (x2 - x1 + 1) * (y2 - y1 + 1)

Parameters

[in]	dev	device descriptor
[in]	x1	x coordinate of the first corner
[in]	x2	x coordinate of the opposite corner
[in]	y1	y coordinate of the first corner
[in]	y2	y coordinate of the opposite corner
[in]	color	array of colors to fill the area with

◆ lcd_read_cmd()

void lcd_read_cmd	(	lcd_t *	dev,
		uint8_t	cmd,
		uint8_t *	data,
		size_t	len )

Raw read command.

Note: Very often the SPI MISO signal of the serial interface or the RDX signal of the MCU 8080 parallel interface are not connected to the display. In this case the read command does not provide valid data.

Precondition: len > 0

Parameters

[in]	dev	device descriptor
[in]	cmd	command
[out]	data	data from the device
[in]	len	length of the returned data

◆ lcd_write_cmd()

void lcd_write_cmd	(	lcd_t *	dev,
		uint8_t	cmd,
		const uint8_t *	data,
		size_t	len )

Raw write command.

Parameters

[in]	dev	device descriptor
[in]	cmd	command code
[in]	data	command data to the device or NULL for commands without data
[in]	len	length of the command data or 0 for commands without data

Detailed Description

Files

Data Structures

Macros

Typedefs

Enumerations

Low-level MCU 8080 8-/16-bit parallel interface

Low-level LCD API

High-level LCD API

Memory access control bits

Macro Definition Documentation

◆ CONFIG_LCD_LE_MODE

◆ LCD_MADCTL_BGR

◆ LCD_MADCTL_MH

◆ LCD_MADCTL_ML

◆ LCD_MADCTL_MV

◆ LCD_MADCTL_MX

◆ LCD_MADCTL_MY

Typedef Documentation

◆ lcd_driver_t

Enumeration Type Documentation

◆ lcd_if_mode_t

Function Documentation

◆ lcd_fill()

◆ lcd_init()

◆ lcd_invert_off()

◆ lcd_invert_on()

◆ lcd_ll_acquire()

◆ lcd_ll_read_cmd()

◆ lcd_ll_release()

◆ lcd_ll_set_area()

◆ lcd_ll_write_cmd()

◆ lcd_pixmap()

◆ lcd_read_cmd()

◆ lcd_write_cmd()