HD44780 Hitachi Semiconductor (acquired by Renesas), HD44780 Datasheet - Page 10

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

HD44780U
Display Data RAM (DDRAM)
Display data RAM (DDRAM) stores display data represented in 8-bit character codes. Its extended
capacity is 80
display can be used as general data RAM. See Figure 1 for the relationships between DDRAM addresses
and positions on the liquid crystal display.
The DDRAM address (A
10
1-line display (N = 0) (Figure 2)
When there are fewer than 80 display characters, the display begins at the head position. For
example, if using only the HD44780, 8 characters are displayed. See Figure 3.
When the display shift operation is performed, the DDRAM address shifts. See Figure 3.
AC
(hexadecimal)
Display position
(digit)
DDRAM
address
(hexadecimal)
8 bits, or 80 characters. The area in display data RAM (DDRAM) that is not used for
AC6 AC5 AC4 AC3 AC2 AC1 AC0
DD
High order
Figure 3 1-Line by 8-Character Display Example
) is set in the address counter (AC) as hexadecimal.
bits
00 01
Display
position
DDRAM
address
For
shift left
For
shift right
1
2
Figure 1 DDRAM Address
Figure 2 1-Line Display
02
Low order
3
00 01 02 03 04 05 06 07
01 02 03 04 05 06 07 08
4F
1
bits
03 04
00 01 02 03 04 05 06
4
2
3
5
4
. . . . . . . . . . . . . . . . . .
5
6
Example: DDRAM address 4E
1
7
0
8
0
1
4E 4F
79
1
80
1
0