hd66420 Renesas Electronics Corporation., hd66420 Datasheet - Page 13

• Manufacturer Part Number: hd66420
• Description: Ram-provided 160 Channel 4-level Grey Scale Driver For Dot Matrix Graphics Lcd
• Manufacturer: Renesas Electronics Corporation.

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.
Table 1 Scanning Direction and RAM Address
DTY1
0
1
COM40
COM1
DTY0
0
1
0
1
H’0
Figure 5 LCD Driver Layout and RAM addresses : 1/80 Duty cycle
ADC
0
1
0
1
0
1
0
1
H’1
a) ADC = 0
LCD panel
HD66420
COMMON
COM1
COM41
COM1
COM49
COM1
COM65
8 COM depend on R11
8 COM depend on R11
COM40, COM80
COM32, COM80
COM16, COM80
COM80, COM40
COM80, COM32
COM80, COM16
COM80
COM41
COM41
COM80
COM41
COM49
COM65
COM1
COM1
COM1
H’0
H’1
LCD panel
b) ADC = 1
HD66420
SEGMENT
H’00
H’00
H’00
H’00
H’00
H’00
H’00
H’00
SEG1
SEG160
SEG1
SEG160
SEG1
SEG160
SEG1
SEG160
HD66420
COM40
COM1
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