HD44780 Hitachi Semiconductor (acquired by Renesas), HD44780 Datasheet - Page 25

• Manufacturer Part Number: HD44780
• Description: Dot Matrix Liquid Crystal Display Controller/driver
• Manufacturer: Hitachi Semiconductor (acquired by Renesas)

Table 6
Instruction RS
Write data
to CG or
DDRAM
Read data
from CG or
DDRAM
Note:
— indicates no effect.
*
Busy signal
(DB7 pin)
Address counter
(DB0 to DB6 pins)
Note: t
1
1
I/D = 1:
I/D = 0:
S
S/C = 1:
S/C = 0:
R/L = 1:
R/L = 0:
DL = 1:
N
F
BF = 1:
BF = 0:
After execution of the CGRAM/DDRAM data write or read instruction, the RAM address counter
is incremented or decremented by 1. The RAM address counter is updated after the busy flag
turns off. In Figure 10, t
counter is updated.
Instructions (cont)
= 1:
= 1:
= 1:
R/W DB7 DB6 DB5 DB4 DB3 DB2 DB1 DB0 Description
0
1
t
ADD
ADD
Write data
Read data
Increment
Decrement
Accompanies display shift
Display shift
Cursor move
Shift to the right
Shift to the left
8 bits, DL = 0: 4 bits
2 lines, N = 0: 1 line
5
Internally operating
Instructions acceptable
depends on the operation frequency
= 1.5/(f
10 dots, F = 0: 5
cp
or f
Code
Figure 10 Address Counter Update
ADD
OSC
is the time elapsed after the busy flag turns off until the address
Busy state
) seconds
8 dots
A
t
ADD
Writes data into DDRAM or
CGRAM.
Reads data from DDRAM or
CGRAM.
DDRAM: Display data RAM
CGRAM: Character generator
ACG:
ADD:
AC: Address counter used for
(corresponds to cursor
address)
both DD and CGRAM
addresses
RAM
CGRAM address
DDRAM address
A + 1
Execution Time
(max) (when f
f
37 s
t
37 s
t
Execution time
changes when
frequency changes
Example:
When f
250 kHz,
37 s
ADD
ADD
OSC
HD44780U
= 4 s*
= 4 s*
is 270 kHz)
cp
270
250
or f
OSC
= 40 s
cp
is
or
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