HD66420 Datasheet, PDF (13/52 Pages) Hitachi Semiconductor – (RAM-Provided 160 Channel 4-Level Grey Scale Driver for Dot Matrix Graphics LCD)

HD66420
Column Address Inversion According to LCD Driver Layout: The HD6420 can always display data in
address H’0 on the top left of an LCD panel regardless of where it is positioned with respect to the panel.
This is because the HD66420 can invert the positional relationship between display RAM addresses and
LCD driver output pins by inverting RAM addresses. Specifically, the HD66420 outputs data in address
H’0 from SEG1 when the ADC bit in control register 1 is 0, and from SEG160 otherwise. Here, the scan
direction of row output is also inverted according to the situation as shown in figure 6. Note that addresses
and scan direction are inverted when data is written to the display RAM, and thus changing the ADC bit
after data has been written has no effect. Therefore. hardware control bits such as ADC must be set
immediately after reset is canceled, and must not be set while data is being displayed.
COM1
COM40
LCD panel
COM80
HD66420
H’0 H’1
COM41
COM41
H’0 H’1
HD66420
COM80
LCD panel
a) ADC = 0
b) ADC = 1
Figure 5 LCD Driver Layout and RAM addresses : 1/80 Duty cycle
Table 1 Scanning Direction and RAM Address
DTY1
0
1
DTY0
0
1
0
1
ADC
0
1
0
1
0
1
0
1
COMMON
COM1 → COM40, COM80 → COM41
COM41 → COM80, COM40 → COM1
COM1 → COM32, COM80 → COM49
COM49 → COM80, COM32 → COM1
COM1 → COM16, COM80 → COM65
COM65 → COM80, COM16 → COM1
8 COM depend on R11
8 COM depend on R11
SEGMENT
H’00 → SEG1
H’00 → SEG160
H’00 → SEG1
H’00 → SEG160
H’00 → SEG1
H’00 → SEG160
H’00 → SEG1
H’00 → SEG160
COM40
COM1
13