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ST7038
Ver 1.1
18/61
2007/01/25
Busy Flag (BF)
When BF is "High
”
(Busy), it indicates that the internal operation is being processed. So during this time the next instruction
cannot be accepted. BF can be read in parallel interface mode. By issuing A0=
”
Low
”
and R/W=
”
High
”
(Read Status
operation), BF (Busy Flag) can be checked on DB7. Before executing the next instruction, be sure that BF is not
“
High
”
.
Address Counter (AC)
Address Counter (AC) stores DDRAM/CGRAM/ICON RAM address which is transferred from IR. After writing into (reading
from) DDRAM/CGRAM/ICON RAM, AC is automatically increased (decreased) by 1. By issuing A0="Low" and R/W="High"
(Read Status Operation), AC can be read on DB6 ~ DB0.
Figure 8
DDRAM Address
Display Data RAM (DDRAM)
Display Data RAM (DDRAM) stores display data represented in 8-bit character codes. Each character code has a unique
font stored in the Character Generator ROM (CGROM). The Display Data RAM (DDRAM) capacity is 80 x 8 bits, or 80
characters. The unused area in Display Data RAM (DDRAM) can be used as general data RAM. Please refer to the following
sections for the relationships between DDRAM address and display position on the LCD module under different display
operation. Please note that: In following demonstration, the DDRAM address in the address counter (AC) is hexadecimal
format while the character position is decimal format.
1-LINE DISPLAY (N2=0, N1=0)
In this mode, each line can use 80 RAM-cells to store the display data. The relation between DDRAM address and display
position is illustrated in Figure 9. For example, 20 characters are displayed (with 100 segments); the default relation between
DDRAM Address and display position is illustrated on the top of Figure 10. When the display shift operation is performed, the
relation is changed, just as shown in Figure 10.
Figure 9
1-Line Display Mode
Figure 10 1-Line Display Mode with 20-Character Display