HD44780

This is a generic HD44780 driver for node. It knows the "language" of the display, but you have to provide the functions that communicates with the hardware. Both 8 and 4 bit interfaces are supported.

Both read and write operations are requied. It reads the BUSY flag and address-counter from the display.

Hardware access funtions

You have to provide the functions that communicates with the hardware.

• async pin_enable(state)

  This function should set the ENABLE line to high if sate is true, and to low if it is false.

• async port_raw_write(rs, data)

  This function should

  • set the hardware to OUTPUT D0-D7 (D4-D7 in 4-bit-mode)
  • set the R/W pin to WRITE (LOW)
  • set the RS pin to HIGH or LOW according to rs variable
  • output data to data-pins. (in 4-bit-mode data is in D4-D7)

• async port_raw_read(rs)

  This function should

  • set the hardware to INPUT D0-D7 (D4-D7 in 4-bit-mode)
  • set the R/W pin to READ (HIGH)
  • set the RS pin to HIGH or LOW according to rs variable
  • read data from data-pins. (in 4-bit-mode data is in D4-D7)

High level functions

async write(text,...args)

Write text to display memory from current position.

A sprintf-like behaviour is supported:

%(flags)(width)(.precision)(specifier)

flags

• "-" Left-justify
• "+" Always add sign
• "0" Left-pads a number with 0 instead of spaces.

width

Minimum number of characters to be printed.

precision

• For b, d, o, x and X this specifies the minimum number of digits to be written. Will be zero-padded if shorter.

• For f this is the number of digits to be printed after the decimal point.

• For s this is the maximum number of characters to be printed.

specifier

• % Prints a % character
• d Print number as decimal
• f Print number as float
• o Print number as octal
• s Print string
• x Print number as hex (lower case)
• X Print number as HEX (upper case)

Supported control-characters

Character		Description
0x07	BEL	Calls the bell function. By default it doses not do anything, but you can override it.
0x08	DEL	Moves cursor back one step and replaces the character there with a space.
0x0A	NEW LINE	Moves cursor to the next line. If it is at the bottom line, it moves to the first line.
0x0C	FROM FEED	Clears the display.
0x0D	CARRIAGE RETURN	Moves the cursor to the start of the current line.
0x0E	SHIFT OUT	Shifts out the normal characters and allow you to use the custom chacters. The custom characters are mapped from 0x30 - 0x37 (digits 0 - 7). Example: "\0x0E0"
0x0F	SHIFT IN	Shift in the normal characters.

async write_xy(x,y,text,...args)

Almost the same as write, but sets the position before writing.

async set_display_control(display, cursor, blink)

async display_visible(state)

async cursor_blink(state)

async cursor_visible(state)

async set_entry_mode(leftOrRight, cursorOrDisplay)

async set_move(displayOrCursor, leftOrRight)

async cursor_move( moveRightOrLeft )

masync display_shift( moveRightOrLeft )

async display_shift_left()

async display_shift_right()

async display_clear()

async display_home()

async bell()

async set_address(addr)

async set_address_xy(x,y)

async store_custom_bitmap( pos, bitmap )

Low level functions

microsleep(µs)

async busy_wait()

async pin_enable_pulse()

sync port_cooked_write(rs, data)

async port_cooked_read(rs)

async send_command( command )

async set_function(datalink8bit, multiline, font5x10)

async init()

calc_address(x, y)

calc_xy(addr)