HD44780 instruction set

Instruction	Code										Description	Execution time**
	RS	R/W	DB7	DB6	DB5	DB4	DB3	DB2	DB1	DB0
Clear display	0	0	0	0	0	0	0	0	0	1	Clears display and returns cursor to the home position (address 0).	1.64mS
Cursor home	0	0	0	0	0	0	0	0	1	*	Returns cursor to home position (address 0). Also returns display being shifted to the original position. DDRAM contents remains unchanged.	1.64mS
Entry mode set	0	0	0	0	0	0	0	1	I/D	S	Sets cursor move direction (I/D), specifies to shift the display (S). These operations are performed during data read/write.	40uS
Display On/Off control	0	0	0	0	0	0	1	D	C	B	Sets On/Off of all display (D), cursor On/Off (C) and blink of cursor position character (B).	40uS
Cursor/display shift	0	0	0	0	0	1	S/C	R/L	*	*	Sets cursor-move or display-shift (S/C), shift direction (R/L). DDRAM contents remains unchanged.	40uS
Function set	0	0	0	0	1	DL	N	F	*	*	Sets interface data length (DL), number of display line (N) and character font(F).	40uS
Set CGRAM address	0	0	0	1	CGRAM address						Sets the CGRAM address. CGRAM data is sent and received after this setting.	40uS
Set DDRAM address	0	0	1	DDRAM address							Sets the DDRAM address. DDRAM data is sent and received after this setting.	40uS
Read busy-flag and address counter	0	1	BF	CGRAM / DDRAM address							Reads Busy-flag (BF) indicating internal operation is being performed and reads CGRAM or DDRAM address counter contents (depending on previous instruction).	0uS
Write to CGRAM or DDRAM	1	0	write data								Writes data to CGRAM or DDRAM.	40uS
Read from CGRAM or DDRAM	1	1	read data								Reads data from CGRAM or DDRAM.	40uS

Remarks:

DDRAM = Display Data RAM.
CGRAM = Character Generator RAM.
DDRAM address corresponds to cursor position.
* = Don't care.
** = Based on F_osc = 250kHz

Bit names

Bit name	Setting / Status
I/D	0 = Decrement cursor position	1 = Increment cursor position
S	0 = No display shift	1 = Display shift
D	0 = Display off	1 = Display on
C	0 = Cursor off	1 = Cursor on
B	0 = Cursor blink off	1 = Cursor blink on
S/C	0 = Move cursor	1 = Shift display
R/L	0 = Shift left	1 = Shift right
DL	0 = 4-bit interface	1 = 8-bit interface
N	0 = 1/8 or 1/11 Duty (1 line)	1 = 1/16 Duty (2 lines)
F	0 = 5x7 dots	1 = 5x10 dots
BF	0 = Can accept instruction	1 = Internal operation in progress

"*" - Not Used/Ignored.  This bit can be either "1" or "0"


Set Cursor Move Direction:
  ID - Increment the Cursor After Each Byte Written to Display if Set
   S - Shift Display when Byte Written to Display


Enable Display/Cursor
   D - Turn Display On(1)/Off(0)
   C - Turn Cursor On(1)/Off(0)
   B - Cursor Blink On(1)/Off(0)


Move Cursor/Shift Display
  SC - Display Shift On(1)/Off(0)
  RL - Direction of Shift Right(1)/Left(0)


Set Interface Length
  DL - Set Data Interface Length 8(1)/4(0)
   N - Number of Display Lines 1(0)/2(1)
   F - Character Font 5x10(1)/5x7(0)


Poll the "Busy Flag"
  BF - This bit is set while the LCD is processing 


Move Cursor to CGRAM/Display
   A - Address


Read/Write ASCII to the Display
   D - Data