mirror of
https://github.com/qmk/qmk_firmware.git
synced 2024-12-14 22:00:53 +00:00
299 lines
8.9 KiB
Markdown
299 lines
8.9 KiB
Markdown
# HD44780 LCD Driver :id=hd44780-lcd-driver
|
|
|
|
## Supported Hardware :id=supported-hardware
|
|
|
|
LCD modules using [HD44780U](https://www.sparkfun.com/datasheets/LCD/HD44780.pdf) 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](https://www.codrey.com/electronic-circuits/hack-your-16x2-lcd/) for more details.
|
|
|
|
## Usage :id=usage
|
|
|
|
Add the following to your `rules.mk`:
|
|
|
|
```make
|
|
HD44780_ENABLE = yes
|
|
```
|
|
|
|
## Basic Configuration :id=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 :id=examples
|
|
|
|
### Hello World :id=example-hello-world
|
|
|
|
Add the following to your `keymap.c`:
|
|
|
|
```c
|
|
void keyboard_post_init_user(void) {
|
|
hd44780_init(true, true); // Show blinking cursor
|
|
hd44780_puts_P(PSTR("Hello, world!\n"));
|
|
}
|
|
```
|
|
|
|
### Custom Character Definition :id=example-custom-character
|
|
|
|
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
|
|
1 | x x x ■ □ ■ □ ■
|
|
2 | x x x ■ □ ■ □ ■
|
|
3 | x x x ■ □ ■ □ ■
|
|
4 | x x x □ ■ ■ ■ □
|
|
5 | x x x □ □ ■ □ □
|
|
6 | x x x □ □ ■ □ □
|
|
7 | x x x □ □ ■ □ □
|
|
8 | x x x □ □ □ □ □
|
|
```
|
|
|
|
```c
|
|
const uint8_t PROGMEM psi[8] = { 0x15, 0x15, 0x15, 0x0E, 0x04, 0x04, 0x04, 0x00 };
|
|
|
|
void keyboard_post_init_user(void) {
|
|
hd44780_init(false, false);
|
|
hd44780_define_char_P(0, psi);
|
|
// Cursor is incremented while defining characters so must be reset
|
|
hd44780_home();
|
|
// 0x08 to avoid null terminator
|
|
hd44780_puts_P(PSTR("\x08 QMK Firmware"));
|
|
}
|
|
```
|
|
|
|
## API :id=api
|
|
|
|
### `void hd44780_init(bool cursor, bool blink)` :id=api-hd44780-init
|
|
|
|
Initialize the display.
|
|
|
|
This function should be called only once, before any of the other functions can be called.
|
|
|
|
#### Arguments :id=api-hd44780-init-arguments
|
|
|
|
- `bool cursor`
|
|
Whether to show the cursor.
|
|
- `bool blink`
|
|
Whether to blink the cursor, if shown.
|
|
|
|
---
|
|
|
|
### `void hd44780_clear(void)` :id=api-hd44780-clear
|
|
|
|
Clear the display.
|
|
|
|
This function is called on init.
|
|
|
|
---
|
|
|
|
### `void hd44780_home(void)` :id=api-hd44780-home
|
|
|
|
Move the cursor to the home position.
|
|
|
|
This function is called on init.
|
|
|
|
---
|
|
|
|
### `void hd44780_on(bool cursor, bool blink)` :id=api-hd44780-on
|
|
|
|
Turn the display on, and/or set the cursor properties.
|
|
|
|
This function is called on init.
|
|
|
|
#### Arguments :id=api-hd44780-on-arguments
|
|
|
|
- `bool cursor`
|
|
Whether to show the cursor.
|
|
- `bool blink`
|
|
Whether to blink the cursor, if shown.
|
|
|
|
---
|
|
|
|
### `void hd44780_off(void)` :id=api-hd44780-off
|
|
|
|
Turn the display off.
|
|
|
|
---
|
|
|
|
### `void hd44780_set_cursor(uint8_t col, uint8_t line)` :id=api-hd44780-set-cursor
|
|
|
|
Move the cursor to the specified position on the display.
|
|
|
|
#### Arguments :id=api-hd44780-set-cursor-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)` :id=api-hd44780-putc
|
|
|
|
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 :id=api-hd44780-putc-arguments
|
|
|
|
- `char c`
|
|
The character to print.
|
|
|
|
---
|
|
|
|
### `void hd44780_puts(const char *s)` :id=api-hd44780-puts
|
|
|
|
Print a string of characters to the display.
|
|
|
|
#### Arguments :id=api-hd44780-puts-arguments
|
|
|
|
- `const char *s`
|
|
The string to print.
|
|
|
|
---
|
|
|
|
### `void hd44780_puts_P(const char *s)` :id=api-hd44780-puts-p
|
|
|
|
Print a string of characters from PROGMEM to the display.
|
|
|
|
On ARM devices, this function is simply an alias of `hd44780_puts()`.
|
|
|
|
#### Arguments :id=api-hd44780-puts-p-arguments
|
|
|
|
- `const char *s`
|
|
The PROGMEM string to print (ie. `PSTR("Hello")`).
|
|
|
|
---
|
|
|
|
### `void hd44780_define_char(uint8_t index, uint8_t *data)` :id=api-hd44780-define-char
|
|
|
|
Define a custom character.
|
|
|
|
#### Arguments :id=api-hd44780-define-char-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)` :id=api-hd44780-define-char-p
|
|
|
|
Define a custom character from PROGMEM.
|
|
|
|
On ARM devices, this function is simply an alias of `hd44780_define_char()`.
|
|
|
|
#### Arguments :id=api-hd44780-define-char-p-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)` :id=api-hd44780-busy
|
|
|
|
Indicates whether the display is currently processing, and cannot accept instructions.
|
|
|
|
#### Return Value :id=api-hd44780-busy-arguments
|
|
|
|
`true` if the display is busy.
|
|
|
|
---
|
|
|
|
### `void hd44780_write(uint8_t data, bool isData)` :id=api-hd44780-write
|
|
|
|
Write a byte to the display.
|
|
|
|
#### Arguments :id=api-hd44780-write-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)` :id=api-hd44780-read
|
|
|
|
Read a byte from the display.
|
|
|
|
#### Arguments :id=api-hd44780-read-arguments
|
|
|
|
- `bool isData`
|
|
Whether to read the current cursor position, or the character at the cursor.
|
|
|
|
#### Return Value :id=api-hd44780-read-return
|
|
|
|
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)` :id=api-hd44780-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 :id=api-hd44780-command-arguments
|
|
|
|
- `uint8_t command`
|
|
The command to send.
|
|
|
|
---
|
|
|
|
### `void hd44780_data(uint8_t data)` :id=api-hd44780-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 :id=api-hd44780-data-arguments
|
|
|
|
- `uint8_t data`
|
|
The byte of data to send.
|
|
|
|
---
|
|
|
|
### `void hd44780_set_cgram_address(uint8_t address)` :id=api-hd44780-set-cgram-address
|
|
|
|
Set the CGRAM address.
|
|
|
|
This function is used when defining custom characters.
|
|
|
|
#### Arguments :id=api-hd44780-set-cgram-address-arguments
|
|
|
|
- `uint8_t address`
|
|
The CGRAM address to move to, from `0x00` to `0x3F`.
|
|
|
|
---
|
|
|
|
### `void hd44780_set_ddram_address(uint8_t address)` :id=api-hd44780-set-ddram-address
|
|
|
|
Set the DDRAM address.
|
|
|
|
This function is used when printing characters to the display, and setting the cursor.
|
|
|
|
#### Arguments :id=api-hd44780-set-ddram-address-arguments
|
|
|
|
- `uint8_t address`
|
|
The DDRAM address to move to, from `0x00` to `0x7F`.
|