The HD44780 Instructions

 

 
 
 
HD44780 Instructions
Instruction                 Code


RS R/W DB7 DB6 DB5 DB4 DB3 DB2 DB1 DB0
Description Execution time
when fosc is
250 KHz
(Note 1)
Execution time
when fosc is
160 KHz
(Note 2)
Clear Display 0   0   0   0   0   0   0   0   0   1 Clears all display and
returns the cursor to 
the home position
82us~1.64 ms 120us~4.9ms
Return home 0   0   0   0   0   0   0   0   1   * Returns the cursor to
the home position.
Also returns the display
being shifted to the
original position. DD
RAM contents
unchanged.
40us~1.6ms 120us~4.8ms
Entry mode set 0   0   0   0   0   0   0   1  I/D  S Sets the cursor move
direction and specifies
or not to shift the display.
These operations are
performed during data
write and read.
      40us       120us
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 char(B)
      40us       120us
Cursor and
Display shift
0   0   0   0   0   1  S/C R/L  *   * Moves the cursor and 
shifts the display without
changing DD RAM contents
      40us       120us
Function set 0   0   0   0   1  DL   N   F   *   * Sets interface data length
(DL), number of lines(L) and
character font (F)
      40us       120us
Set CG RAM
address
0   0   0   1       CG ADDRESS Sets the CG RAM address.
CG RAM data is sent or 
received after this setting
      40us       120us
Set DD RAM
address
0   0   1        DD ADDRESS Sets the DD RAM address.
DD RAM data is sent of
received after this setting
      40us       120us
Read busy flag
and address
0   1  BF      ADDRESS COUNTER Reads Busy flag (BF) and 
address counter contents
      1us       1 us
Write data to
CG or DD RAM
1   0        WRITE DATA Writes data into DD or CG
RAM
      40us       120us
Read data from
CG or DD RAM
1   1        READ DATA Reads data from DD or CG
RAM
      40us       120us
I/D =1:Increment         I/D=0: Decrement
S   =1:Accompanies display shift
S/C=1:Display shift    S/C=0:Cursor move
R/L=1:Shift to the right
R/L=0:Shift to the left
DL =1:8 bits               DL=0:4 bits
N   =1:2 lines              N=0: 1 line
F   =1:5X10 dots        F=0: 5X7 dots
BF =1: Internally operating (busy)
BF =0: Can accept instructions (ready)
DD RAM: Display data RAM
CG RAM: Character gener-
ator RAM
us=micro sec
ms=milli sec
Notes: * = no effect
1. Applied to models driven by 1/8 or 1/11 duty cycle
2. Applied to models driven by 1/16 duty cycle

My home page is http://www.hkrmicrop.com/personal/index.html .