336
13.3.2
Relationship between LCD RAM and Display
The relationship between the LCD RAM and the display segments differs according to the duty
cycle. LCD RAM maps for the different duty cycles when segment external expansion is not used
are shown in figures 13.5 to 13.8, and LCD RAM maps when segment external expansion is used
in figures 13.9 to 13.12.
After setting the registers required for display, data is written to the part corresponding to the duty
using the same kind of instruction as for ordinary RAM, and display is started automatically when
turned on. Word- or byte-access instructions can be used for RAM setting.
bit7
bit6
bit5
bit4
bit3
bit2
bit1
bit0
SEG
2
SEG
2
SEG
2
SEG
2
SEG
1
SEG
1
SEG
1
SEG
1
SEG
32
H'F740
H'F74F
SEG
32
SEG
32
SEG
32
SEG
31
SEG
31
SEG
31
SEG
31
COM
4
COM
3
COM
2
COM
1
COM
4
COM
3
COM
2
COM
1
Figure 13.5 LCD RAM Map when Not Using Segment External Expansion (1/4 Duty)