ST7066

V1.2

2000/6/13

7

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.

!" 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 ST7066, 8 characters are displayed. See Figure 3.

When the display shift operation is performed, the DDRAM address shifts. See Figure 3.

Figure 1 DDRAM Address

Figure 1 DDRAM Address

Figure 1 DDRAM Address

Figure 1 DDRAM Address

Figure 2 1

Figure 2 1

Figure 2 1

Figure 2 1----Line Display

Line Display

Line Display

Line Display

Figure 3 1

Figure 3 1

Figure 3 1

Figure 3 1----Line by 8

Line by 8

Line by 8

Line by 8----Character Display Example

Character Display Example

Character Display Example

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 ST7066 is

used, 8 characters

× 2 lines are displayed. See Figure 5.

AC6 AC5 AC4 AC3 AC2 AC1 AC0

1

0

0

1

1

1

1

High Order

bits

Low Order

bits

AC

Example: DDRAM Address 4F

00

01

02

03

04

05

4D

4E

4F

DDRAM Address

………………..

1

2

3

4

5

6

80

79

78

Display

Position

(Digit)

00

01

02

03

04

05

06

07

DDRAM

Address

1

2

3

4

5

6

8

7

Display

Position

08

01

02

03

04

05

06

07

00

01

02

03

04

05

06

4F

For

Shift Left

For

Shift Right