hd44780.h Header file for the Hitachi LCD display driver Copyright U. Raich Jan. 2017 This program is part of a course on embedded systems held at the University of Cape Coast, Ghana in 2017 It is released under the GNU Public License For details please see https://www.gnu.org/licenses/gpl.html More...

#include <stdio.h>
#include <pigpiod_if2.h>
#include <errno.h>
#include <unistd.h>
#include <stdbool.h>
#include <string.h>

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Macros
#define	I2C_BUS 1

#define	I2C_FLAGS 0

#define	HD44780_ADDRESS 0x3f

#define	HD44780_CLEAR 0x01

#define	HD44780_HOME 0x02

#define	HD44780_ENTRY_MODE 0x04

#define	HD44780_CURSOR_DIR 0x02

#define	HD44780_CURSOR_SHIFT 0x10

#define	HD44780_DISPLAY_CURSOR 0x08

#define	HD44780_DISPLAY_ON 0x04

#define	HD44780_DISPLAY_OFF 0x00

#define	HD44780_CURSOR_ON 0x02

#define	HD44780_CURSOR_OFF 0x00

#define	HD44780_CURSOR_BLINK 0x01

#define	HD44780_CURSOR_NOBLINK 0x00

#define	HD44780_ENTIRE_DISPLAY 0x04

#define	HD44780_CURSOR_ONOFF 0x02

#define	HD44780_BLINK 0x01

#define	HD44780_CURSOR 0x10

#define	HD44780_1_LINE 0x00

#define	DH44780_CURSOR_MOVE 0x00

#define	DH44780_DISPLAY_SHIFT 0x08

#define	DH44780_SHIFT_LEFT 0x00

#define	DH44780_SHIFT_RIGHT 0x04

#define	HD44780_FUNCTION 0x20

#define	HD44789_8_BIT_MODE 0x10

#define	HD44780_4_BIT_MODE 0x00

#define	HD44780_TWO_LINES 0x08

#define	HD44780_5x10_FONT 0x04

#define	HD44780_5x8_FONT 0x00

#define	HD44780_1_LINE 0x00

#define	HD44780_2_LINE 0x08

#define	HD44780_CURSOR_DEC 0x00

#define	HD44780_CURSOR_INC 0x02

#define	HD44780_DISPLAY_SHIFT 0x01

#define	HD44780_CGRAM_AHDR 0x10

#define	HD44780_HDRAM_AHDR 0x20

#define	HD44780_BUSY_FLAG 0x40

#define	HD44780_BL 0x08

#define	HD44780_EN 0x04

#define	HD44780_READ 0x02

#define	HD44780_WRITE 0x00

#define	HD44780_CMD_REG 0x00

#define	HD44780_DATA_REG 0x01

#define	HD44780_SET_DDRAM 0x80

#define	HD44780_SET_CGRAM 0x40

#define	HD44780_2ND_LINE 0x40

#define	HD44780_INCREMENT true

#define	HD44780_DECREMENT false

#define	HD44780_ON true

#define	HD44780_OFF false

#define	HD44780_SUCCESS 0

#define	HD44780_MAX_STRLEN 16

Functions
void	hd44780SetDebug (bool)
	switches debug mode on or off More...

int	hd44780BackLight (bool)
	switches the display back light on or off More...

int	hd44780PutC (char)
	Write a character to the display. More...

int	hd44780GetC (char *)
	Read a character from the display. More...

int	hd44780ReadBusy (bool , unsigned char )
	Reads the busy flag and the DDRAM address. More...

int	hd44780PutS (char *)
	Writes a zero terminated character string to the display Not more than 16 characters are written it no zero is found. More...

int	hd44780Home (void)
	Sets the DDRAM address to zero such that the next character is written to the top left position if the LED screen. If the display is shifted it is set back to the original position. More...

int	hd44780Clear (void)
	Clears the display. More...

int	hd44780Cursor (bool, bool)
	Sets the DDRAM address to zero such that the next character is written to the top left position if the LED screen. If the display is shifted it is set back to the original position. More...

int	hd44780EntryMode (bool, bool)
	Defines if the address counter counts up or down and sets shifting the whole display on or off. More...

int	hd44780SetDDRamAddr (unsigned char)
	Sets the DDRAM address. More...

int	hd44780SecondLine (void)
	Sets the DDRAM address to the beginning of the second line. More...

int	hd44780CreateChar (unsigned char, unsigned char *)
	hd44780CreateChar: creates a character in the character generator RAM (CGRAM) More...

int	hd44780Open (void)
	hd44770Open: initializes the pigpio library opens the I2C connection to the pcf8574 which is on the I2C address 0x3f More...

void	hd44780Close (void)
	hd44770Close: closes the I2C connection to the pcf8574 and disconnects from the pigpio library More...

Detailed Description

hd44780.h Header file for the Hitachi LCD display driver Copyright U. Raich Jan. 2017 This program is part of a course on embedded systems held at the University of Cape Coast, Ghana in 2017 It is released under the GNU Public License For details please see https://www.gnu.org/licenses/gpl.html

Function Documentation

◆ hd44780BackLight()

int hd44780BackLight ( bool onOff )

switches the display back light on or off

Parameters

onOff true: switches debug mode on
false: switches debug mode off

Returns: result from the call to the pigpio library

Return values

HD44780_SUCCESS	-> success
negative	error code from the pigpio library

◆ hd44780Clear()

int hd44780Clear ( void )

Clears the display.

Returns: result from the call to the hd44780WriteCmd function

Return values

HD44780_SUCCESS	-> success
negative	error code from the hd44780WriteCmd function

◆ hd44780Close()

void hd44780Close ( void )

hd44770Close: closes the I2C connection to the pcf8574 and disconnects from the pigpio library

◆ hd44780CreateChar()

int hd44780CreateChar	(	unsigned char	cgramAddr,
		unsigned char *	dotMatrix
	)

hd44780CreateChar: creates a character in the character generator RAM (CGRAM)

Parameters

address	the address in the CGRAM where to write the character must be on a 8 byte boundary
character	the dot matrix consisting of 7 bytes

Return values

HD44780_SUCCESS	-> success
negative	error code from the hd44780putC function

◆ hd44780Cursor()

int hd44780Cursor	(	bool	onOff,
		bool	blink
	)

Sets the DDRAM address to zero such that the next character is written to the top left position if the LED screen. If the display is shifted it is set back to the original position.

Returns: result from the call to the hd44780WriteCmd function

Return values

HD44780_SUCCESS	-> success
negative	error code from the hd44780WriteCmd function

◆ hd44780EntryMode()

int hd44780EntryMode	(	bool	incDec,
		bool	shift
	)

Defines if the address counter counts up or down
and sets shifting the whole display on or off.

Parameters

incDec	false: the address counter is decremented when a character is written true: it is incremented
shift	false: display shifts are switched off true: they are switched on

Returns: result from the call to the hd44780WriteCmd function

Return values

HD44780_SUCCESS	-> success
negative	error code from the hd44780WriteCmd function

◆ hd44780GetC()

int hd44780GetC ( char * c )

Read a character from the display.

Parameters

c	pointer to the character read from the display controller

Returns: result from the call to the hd44780Read function

Return values

HD44780_SUCCESS	-> success
negative	error code from the hd44780Read function

◆ hd44780Home()

int hd44780Home ( void )

Sets the DDRAM address to zero such that the next character is written to the top left position if the LED screen. If the display is shifted it is set back to the original position.

Returns: result from the call to the hd44780WriteCmd function

Return values

HD44780_SUCCESS	-> success
negative	error code from the hd44780WriteCmd function

◆ hd44780Open()

int hd44780Open ( void )

hd44770Open: initializes the pigpio library opens the I2C connection to the pcf8574 which is on the I2C address 0x3f

Returns: result from the call to the pigpio library

Return values

HD44780_SUCCESS	-> success
negative	error code from the pigpio library

◆ hd44780PutC()

int hd44780PutC ( char c )

Write a character to the display.

Parameters

c	the character to be written

Returns: result from the call to the hd44780WriteCmd function

Return values

HD44780_SUCCESS	-> success
negative	error code from the hd44780WriteCmd function

◆ hd44780PutS()

int hd44780PutS ( char * text )

Writes a zero terminated character string to the display Not more than 16 characters are written it no zero is found.

Parameters

text	the zero terminated C character string

Returns: result from the call to the hd44780PutC function

Return values

HD44780_SUCCESS	-> success
negative	error code from the hd44780PutC function

◆ hd44780ReadBusy()

int hd44780ReadBusy	(	bool *	busy,
		unsigned char *	address
	)

Reads the busy flag and the DDRAM address.

Parameters

*busy	a pointer to a boolean into which the busy flag will be written
*address	a pointer to an unsigned char into which the DDRAM address will be written

Returns: result from the call to the hd44780Read function

Return values

HD44780_SUCCESS	-> success
negative	error code from the hd44780Read function

◆ hd44780SecondLine()

int hd44780SecondLine ( void )

Sets the DDRAM address to the beginning of the second line.

Returns: result from the call to hd44780SetDDRamAddr()

◆ hd44780SetDDRamAddr()

int hd44780SetDDRamAddr ( unsigned char addr )

Sets the DDRAM address.

Parameters

addr	the DDRAM address to which the next character will be written or read from

Returns: result from the call to the hd44780WriteCmd function

Return values

HD44780_SUCCESS	-> success
negative	error code from the hd44780WriteCmd function

◆ hd44780SetDebug()

void hd44780SetDebug ( bool onOff )

switches debug mode on or off

pinout for 20x2 LCD via PCF8574AN:

0x80 P7 - - D7 0x40 P6 - - D6 0x20 P5 - - D5

0x10 P4 - - D4

0x08 P3 - - BL Backlight (LCD has 3 RGB LEDs - common anode) 0x04 P2 - - EN Starts Data read/write 0x02 P1 - - RW low: write, high: read 0x01 P0 - - RS Register Select: 0: Instruction Register (IR) (AC when read), 1: data register (DR)

Parameters

onOff true: switches debug mode on
false: switches debug mode off

Macros

Functions

Detailed Description

Function Documentation

◆ hd44780BackLight()

◆ hd44780Clear()

◆ hd44780Close()

◆ hd44780CreateChar()

◆ hd44780Cursor()

◆ hd44780EntryMode()

◆ hd44780GetC()

◆ hd44780Home()

◆ hd44780Open()

◆ hd44780PutC()

◆ hd44780PutS()

◆ hd44780ReadBusy()

◆ hd44780SecondLine()

◆ hd44780SetDDRamAddr()

◆ hd44780SetDebug()

pinout for 20x2 LCD via PCF8574AN:

0x10 P4 - - D4