HD44780 driver rework (#16370)

2 files changed, 294 insertions, 53 deletions

diff --git a/docs/_summary.md b/docs/_summary.md
index 250a48fe6b..249bfcd9ed 100644
--- a/docs/_summary.md
+++ b/docs/_summary.md
@@ -94,7 +94,7 @@
 
   * Hardware Features
     * Displays
-      * [HD44780 LCD Controller](feature_hd44780.md)
+      * [HD44780 LCD Driver](feature_hd44780.md)
       * [ST7565 LCD Driver](feature_st7565.md)
       * [OLED Driver](feature_oled_driver.md)
     * Lighting
diff --git a/docs/feature_hd44780.md b/docs/feature_hd44780.md
index dc476c734f..4ade640baa 100644
--- a/docs/feature_hd44780.md
+++ b/docs/feature_hd44780.md
@@ -1,57 +1,298 @@
-# HD44780 LCD Displays
-
-This is an integration of Peter Fleury's LCD library. This page will explain the basics. [For in depth documentation visit his page.](http://www.peterfleury.epizy.com/doxygen/avr-gcc-libraries/group__pfleury__lcd.html)
-
-You can enable support for HD44780 Displays by setting the `HD44780_ENABLE` flag in your keyboards `rules.mk` to yes.
-
-## Configuration
-
-You will need to configure the pins used by your display, and its number of lines and columns in your keyboard's `config.h`.
-
-
-Uncomment the section labled HD44780 and change the parameters as needed.
-````
-/*
- * HD44780 LCD Display Configuration
- */
-
-#define LCD_LINES           2     //< number of visible lines of the display
-#define LCD_DISP_LENGTH    16     //< visibles characters per line of the display
-#define LCD_IO_MODE      1            //< 0: memory mapped mode, 1: IO port mode
-#if LCD_IO_MODE
-#define LCD_PORT         PORTB        //< port for the LCD lines
-#define LCD_DATA0_PORT   LCD_PORT     //< port for 4bit data bit 0
-#define LCD_DATA1_PORT   LCD_PORT     //< port for 4bit data bit 1
-#define LCD_DATA2_PORT   LCD_PORT     //< port for 4bit data bit 2
-#define LCD_DATA3_PORT   LCD_PORT     //< port for 4bit data bit 3
-#define LCD_DATA0_PIN    4            //< pin for 4bit data bit 0
-#define LCD_DATA1_PIN    5            //< pin for 4bit data bit 1
-#define LCD_DATA2_PIN    6            //< pin for 4bit data bit 2
-#define LCD_DATA3_PIN    7            //< pin for 4bit data bit 3
-#define LCD_RS_PORT      LCD_PORT     //< port for RS line        
-#define LCD_RS_PIN       3            //< pin  for RS line        
-#define LCD_RW_PORT      LCD_PORT     //< port for RW line        
-#define LCD_RW_PIN       2            //< pin  for RW line        
-#define LCD_E_PORT       LCD_PORT     //< port for Enable line     
-#define LCD_E_PIN        1            //< pin  for Enable line    
-#endif
-````
-
-Should you need to configure other properties you can copy them from `quantum/hd44780.h` and set them in your `config.h`
+# HD44780 LCD Driver
+
+## 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
 
-To initialize your display, call `lcd_init()` with one of these parameters:
-````
-LCD_DISP_OFF             : display off
-LCD_DISP_ON              : display on, cursor off
-LCD_DISP_ON_CURSOR       : display on, cursor on
-LCD_DISP_ON_CURSOR_BLINK : display on, cursor on flashing
-````
-This is best done in your keyboards `matrix_init_kb` or your keymaps `matrix_init_user`.  
-It is advised to clear the display before use.  
-To do so call `lcd_clrscr()`.
+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`:
+
+```c
+void keyboard_post_init_user(void) {
+    hd44780_init(true, true); // Show blinking cursor
+    hd44780_puts_P(PSTR("Hello, world!\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
+   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
+
+### `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.
 
-To now print something to your Display you first call `lcd_gotoxy(column, line)`. To go to the start of the first line you would call `lcd_gotoxy(0, 0)` and then print a string with `lcd_puts("example string")`.
+#### Arguments
 
-There are more methods available to control the display. [For in depth documentation please visit the linked page.](http://www.peterfleury.epizy.com/doxygen/avr-gcc-libraries/group__pfleury__lcd.html)
+ - `uint8_t address`  
+   The DDRAM address to move to, from `0x00` to `0x7F`.