ST7066U
#" Display Data RAM (DDRAM)
Display data RAM (DDRAM) stores display data represented in 8-bit character codes. Its extended capacity is 80
x 8 bits, or 80 characters. The area in display data RAM (DDRAM) that is not used for 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 (ADD ) is set in the address counter (AC) as hexadecimal.
$" 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 ST7066U, 8 characters are displayed. See Figure 3.
When the display shift operation is performed, the DDRAM address shifts. See Figure 3.
High Order Low Order
bits
bits
Example: DDRAM Address 4F
AC
AC6 AC5 AC4 AC3 AC2 AC1 AC0
1
0
0
1
1
1
1
Figure 1 DDRAM Address
Display
Position
(Digit)
1
2
3
4
5
6
78 79 80
4D 4E 4F
00 01 02 03 04 05
………………..
DDRAM Address
Figure 2 1-Line Display
Display
Position
1
2
3
4
5
6
7
8
00 01 02 03 04 05 06 07
DDRAM
Address
For
01 02 03 04 05 06 07 08
4F 00 01 02 03 04 05 06
Shift Left
For
Shift Right
Figure 3 1-Line by 8-Character Display Example
$" 2-line display (N = 1) (Figure 4)
Case 1: When the number of display characters is less than 40 × 2 lines, the two lines are displayed from the head. Note
that the first line end address and the second line start address are not consecutive. For example, when just the
ST7066U is used, 8 characters × 2 lines are displayed. See Figure 5.
V2.0
2001/03/01
10/42
POWERTIP [ POWERTIP TECHNOLOGY ]
