HD44780 LCD driver

Driver for the Hitachi HD44780 LCD driver.

Note

The driver currently supports direct addressing, no I2C

enum hd44780_state_t
HD44780_OFF
disable feature
HD44780_ON
enable feature
int hd44780_init(hd44780_t * dev, const hd44780_params_t * params)

Initialize the given driver.

Parameters

dev:device descriptor of display to initialize
params:configuration parameters

Return values

  • 0 on success, otherwise error
void hd44780_clear(const hd44780_t * dev)

Clear display, delete all chars.

Parameters

dev:device descriptor of LCD

void hd44780_home(const hd44780_t * dev)

Reset cursor to row 0 and column 0.

Parameters

dev:device descriptor of LCD

void hd44780_set_cursor(const hd44780_t * dev, uint8_t col, uint8_t row)

Set cursor to specific position in column and row.

Parameters

dev:device descriptor of LCD
col:column position
row:row position

void hd44780_display(hd44780_t * dev, hd44780.h::hd44780_state_t state)

Turn display on or off.

Parameters

dev:device descriptor of LCD
state:display on or off

void hd44780_cursor(hd44780_t * dev, hd44780.h::hd44780_state_t state)

Show cursor, on or off.

Parameters

dev:device descriptor of LCD
state:cursor on or off

void hd44780_blink(hd44780_t * dev, hd44780.h::hd44780_state_t state)

Blink cursor, on or off.

Parameters

dev:device descriptor of LCD
state:blink on or off

void hd44780_scroll_left(const hd44780_t * dev)

Enable left scrolling.

Parameters

dev:device descriptor of LCD

void hd44780_scroll_right(const hd44780_t * dev)

Enable right scrolling.

Parameters

dev:device descriptor of LCD

void hd44780_left2right(hd44780_t * dev)

Set display direction left to right.

Parameters

dev:device descriptor of LCD

void hd44780_right2left(hd44780_t * dev)

Set display direction right to left.

Parameters

dev:device descriptor of LCD

void hd44780_autoscroll(hd44780_t * dev, hd44780.h::hd44780_state_t state)

Display autoscroll on or off.

Parameters

dev:device descriptor of LCD
state:scroll on or off

void hd44780_create_char(const hd44780_t * dev, uint8_t location, uint8_t charmap)

Create and store a custom character on display memory.

Parameters

dev:device descriptor of LCD
location:memory location
charmap:character bitmap

void hd44780_write(const hd44780_t * dev, uint8_t value)

Write a single character on the LCD.

Parameters

dev:device descriptor of LCD
value:the character to print, i.e., memory location

void hd44780_print(const hd44780_t * dev, const char * data)

Write a string on the LCD.

Parameters

dev:device descriptor of LCD
data:the string to print

HD44780_MAX_COLS

Maximal number of columns supported by the driver. 

1
(40U)
HD44780_MAX_ROWS

Maximal number of rows supported by the driver. 

1
(4U)
HD44780_MAX_PINS

Number of data pins for communication 4 or 8. 

1
(8U)
HD44780_RW_OFF

Specific value to turn rw pin off, if unused. 

1
(255U)
HD44780_CGRAM_SIZE

Size of RAM for custom chars. 

1
(8U)

Generally the driver could support 8 chars of size 5x8 or 4 of size 5x10. However, most displays only use the former, which is (hard wired) default.

struct hd44780_params_t

Parameters needed for device initialization.

uint8_t cols

number of LCD cols

uint8_t rows

number of LCD rows

gpio.h::gpio_t rs

rs gpio pin

gpio.h::gpio_t rw

rw gpio pin

gpio.h::gpio_t enable

enable gpio pin

gpio.h::gpio_t data()

data gpio pins

struct hd44780_t

Device descriptor for HD44780 LCD.

hd44780_params_t p

LCD config parameters.

uint8_t flag

LCD functional flags.

uint8_t ctrl

LCD control flags.

uint8_t mode

LCD mode flags.

uint8_t roff()

offsets for LCD rows