import { _ as _export_sfc, c as createElementBlock, o as openBlock, a8 as createStaticVNode } from "./chunks/framework.B9AX-CPi.js"; const __pageData = JSON.parse('{"title":"HD44780 LCD Driver","description":"","frontmatter":{},"headers":[],"relativePath":"features/hd44780.md","filePath":"features/hd44780.md","lastUpdated":null}'); const _sfc_main = { name: "features/hd44780.md" }; const _hoisted_1 = /* @__PURE__ */ createStaticVNode('

HD44780 LCD Driver

Supported Hardware

LCD modules using HD44780U IC or equivalent, communicating in 4-bit mode.

Module	Size	Notes
1602A	16x2, 5x8 dots
2004A	20x4, 5x8 dots	Untested, not currently supported

To run these modules at 3.3V, an additional MAX660 voltage converter IC must be soldered on, along with two 10µF capacitors. See this page for more details.

Usage

Add the following to your rules.mk:

make

HD44780_ENABLE = yes

Basic Configuration

Add the following to your config.h:

Define	Default	Description
`HD44780_DATA_PINS`	Not defined	(Required) An array of four GPIO pins connected to the display's D4-D7 pins, eg. `{ B1, B3, B2, B6 }`
`HD44780_RS_PIN`	Not defined	(Required) The GPIO connected to the display's RS pin
`HD44780_RW_PIN`	Not defined	(Required) The GPIO connected to the display's RW pin
`HD44780_E_PIN`	Not defined	(Required) The GPIO connected to the display's E pin
`HD44780_DISPLAY_COLS`	`16`	The number of visible characters on a single line of the display
`HD44780_DISPLAY_LINES`	`2`	The number of visible lines on the display
`HD44780_WRAP_LINES`	Not defined	If defined, input characters will wrap to the next line

Examples

Hello World

Add the following to your keymap.c:

void keyboard_post_init_user(void) {\n    hd44780_init(true, true); // Show blinking cursor\n    hd44780_puts_P(PSTR("Hello, world!\\n"));\n}

Custom Character Definition

Up to eight custom characters can be defined. This data is stored in the Character Generator RAM (CGRAM), and is not persistent across power cycles.

This example defines the QMK Psi as the first custom character. The first 16 positions in the character set are reserved for the eight custom characters duplicated.

Byte |      16 8 4 2 1\n   1 | x x x ■ □ ■ □ ■\n   2 | x x x ■ □ ■ □ ■\n   3 | x x x ■ □ ■ □ ■\n   4 | x x x □ ■ ■ ■ □\n   5 | x x x □ □ ■ □ □\n   6 | x x x □ □ ■ □ □\n   7 | x x x □ □ ■ □ □\n   8 | x x x □ □ □ □ □

const uint8_t PROGMEM psi[8] = { 0x15, 0x15, 0x15, 0x0E, 0x04, 0x04, 0x04, 0x00 };\n\nvoid keyboard_post_init_user(void) {\n    hd44780_init(false, false);\n    hd44780_define_char_P(0, psi);\n    // Cursor is incremented while defining characters so must be reset\n    hd44780_home();\n    // 0x08 to avoid null terminator\n    hd44780_puts_P(PSTR("\\x08 QMK Firmware"));\n}

API

`void hd44780_init(bool cursor, bool blink)`

Initialize the display.

This function should be called only once, before any of the other functions can be called.

Arguments

bool cursor
Whether to show the cursor.
bool blink
Whether to blink the cursor, if shown.

`void hd44780_clear(void)`

Clear the display.

This function is called on init.

`void hd44780_home(void)`

Move the cursor to the home position.

This function is called on init.

`void hd44780_on(bool cursor, bool blink)`

Turn the display on, and/or set the cursor properties.

This function is called on init.

Arguments

bool cursor
Whether to show the cursor.
bool blink
Whether to blink the cursor, if shown.

`void hd44780_off(void)`

Turn the display off.

`void hd44780_set_cursor(uint8_t col, uint8_t line)`

Move the cursor to the specified position on the display.

Arguments

uint8_t col
The column number to move to, from 0 to 15 on 16x2 displays.
bool line
The line number to move to, either 0 or 1 on 16x2 displays.

`void hd44780_putc(char c)`

Print a character to the display. The newline character \\n will move the cursor to the start of the next line.

The exact character shown may depend on the ROM code of your particular display - refer to the datasheet for the full character set.

Arguments

char c
The character to print.

`void hd44780_puts(const char *s)`

Print a string of characters to the display.

Arguments

const char *s
The string to print.

`void hd44780_puts_P(const char *s)`

Print a string of characters from PROGMEM to the display.

On ARM devices, this function is simply an alias of hd44780_puts().

Arguments

const char *s
The PROGMEM string to print (ie. PSTR("Hello")).

`void hd44780_define_char(uint8_t index, uint8_t *data)`

Define a custom character.

Arguments

uint8_t index
The index of the custom character to define, from 0 to 7.
uint8_t *data
An array of 8 bytes containing the 5-bit row data of the character, where the first byte is the topmost row, and the least significant bit of each byte is the rightmost column.

`void hd44780_define_char_P(uint8_t index, const uint8_t *data)`

Define a custom character from PROGMEM.

On ARM devices, this function is simply an alias of hd44780_define_char().

Arguments

uint8_t index
The index of the custom character to define, from 0 to 7.
const uint8_t *data
A PROGMEM array of 8 bytes containing the 5-bit row data of the character, where the first byte is the topmost row, and the least significant bit of each byte is the rightmost column.

`bool hd44780_busy(void)`

Indicates whether the display is currently processing, and cannot accept instructions.

Return Value

true if the display is busy.

`void hd44780_write(uint8_t data, bool isData)`

Write a byte to the display.

Arguments

uint8_t data
The byte to send to the display.
bool isData
Whether the byte is an instruction or character data.

`uint8_t hd44780_read(bool isData)`

Read a byte from the display.

Arguments

bool isData
Whether to read the current cursor position, or the character at the cursor.

Return Value

If isData is true, the returned byte will be the character at the current DDRAM address. Otherwise, it will be the current DDRAM address and the busy flag.

`void hd44780_command(uint8_t command)`

Send a command to the display. Refer to the datasheet and hd44780.h for the valid commands and defines.

This function waits for the display to clear the busy flag before sending the command.

Arguments

uint8_t command
The command to send.

`void hd44780_data(uint8_t data)`

Send a byte of data to the display.

This function waits for the display to clear the busy flag before sending the data.

Arguments

uint8_t data
The byte of data to send.

`void hd44780_set_cgram_address(uint8_t address)`

Set the CGRAM address.

This function is used when defining custom characters.

Arguments

uint8_t address
The CGRAM address to move to, from 0x00 to 0x3F.

`void hd44780_set_ddram_address(uint8_t address)`

Set the DDRAM address.

This function is used when printing characters to the display, and setting the cursor.

Arguments

uint8_t address
The DDRAM address to move to, from 0x00 to 0x7F.

', 117); const _hoisted_118 = [ _hoisted_1 ]; function _sfc_render(_ctx, _cache, $props, $setup, $data, $options) { return openBlock(), createElementBlock("div", null, _hoisted_118); } const hd44780 = /* @__PURE__ */ _export_sfc(_sfc_main, [["render", _sfc_render]]); export { __pageData, hd44780 as default };

HD44780 LCD Driver ​

Supported Hardware ​

Usage ​

Basic Configuration ​

Examples ​

Hello World ​

Custom Character Definition ​

API ​

void hd44780_init(bool cursor, bool blink) ​

Arguments ​

void hd44780_clear(void) ​

void hd44780_home(void) ​

void hd44780_on(bool cursor, bool blink) ​

Arguments ​

void hd44780_off(void) ​

void hd44780_set_cursor(uint8_t col, uint8_t line) ​

Arguments ​

void hd44780_putc(char c) ​

Arguments ​

void hd44780_puts(const char *s) ​

Arguments ​

void hd44780_puts_P(const char *s) ​

Arguments ​

void hd44780_define_char(uint8_t index, uint8_t *data) ​

Arguments ​

void hd44780_define_char_P(uint8_t index, const uint8_t *data) ​

Arguments ​

bool hd44780_busy(void) ​

Return Value ​

void hd44780_write(uint8_t data, bool isData) ​

Arguments ​

uint8_t hd44780_read(bool isData) ​

Arguments ​

Return Value ​

void hd44780_command(uint8_t command) ​

Arguments ​

void hd44780_data(uint8_t data) ​

Arguments ​

void hd44780_set_cgram_address(uint8_t address) ​

Arguments ​

void hd44780_set_ddram_address(uint8_t address) ​

Arguments ​

HD44780 LCD Driver

Supported Hardware

Usage

Basic Configuration

Examples

Hello World

Custom Character Definition

API

`void hd44780_init(bool cursor, bool blink)`

Arguments

`void hd44780_clear(void)`

`void hd44780_home(void)`

`void hd44780_on(bool cursor, bool blink)`

Arguments

`void hd44780_off(void)`

`void hd44780_set_cursor(uint8_t col, uint8_t line)`

Arguments

`void hd44780_putc(char c)`

Arguments

`void hd44780_puts(const char *s)`

Arguments

`void hd44780_puts_P(const char *s)`

Arguments

`void hd44780_define_char(uint8_t index, uint8_t *data)`

Arguments

`void hd44780_define_char_P(uint8_t index, const uint8_t *data)`

Arguments

`bool hd44780_busy(void)`

Return Value

`void hd44780_write(uint8_t data, bool isData)`

Arguments

`uint8_t hd44780_read(bool isData)`

Arguments

Return Value

`void hd44780_command(uint8_t command)`

Arguments

`void hd44780_data(uint8_t data)`

Arguments

`void hd44780_set_cgram_address(uint8_t address)`

Arguments

`void hd44780_set_ddram_address(uint8_t address)`

Arguments