hd66421 Renesas Electronics Corporation., hd66421 Datasheet - Page 16

• Manufacturer Part Number: hd66421
• Description: Ram-provided 160 Channel 4-level Grey Scale Driver For Dot Matrix Graphics Lcd
• Manufacturer: Renesas Electronics Corporation.

Display RAM Configuration and Display
The HD66421 incorporates a bit-mapped display
RAM. It has 320 bits in the X direction and 100
bits in the Y direction. The 320 bits are divided
into forty 8-bit groups. As shown in figure 7, data
written by the MPU is stored horizontally with the
MSB at the far left and the LSB at the far right.
The consecutive two bits control one pixel of LCD
in 4-level gray scale mode, this means that one
8-bits data contains data which controls four
pixels. One bit of memory designates one dot of
display in the monochrome display mode.
Preliminary
H'00
H'01
H'62
H'63
Y0
Y1
SEG1
1 1 1 0 0 1 0 0
0 0 0 1 1 0 1 1
D
B
7
SEG1
MSB
D
B
6
H'0
SEG2
D
B
5
(a) MON = 0, ADC = 0, WLS= 0
D
B
4
(a) MON = 0, ADC = 0, WLS= 0
SEG3
D
B
3
H'1
LCD drive signal output
D
B
2
SEG4
D
B
1
Figure 7 Display RAM Data and Display in Gray Scale Mode
Figure 8 Display RAM Configuration in Gray Scale Mode
D
B
0
X addresses
LCD panel
Display RAM
SEG160
H'27
SEG160
16
The ADC bit of control register 1 can control the
positional relationship between X addresses of the
RAM and LCD driver output (figure 8).
Specifically. the data in address H'0 is output
from SEG1 when the ADC bit in control register
1 is 0, and from SEG160 otherwise. Here. data in
each 8-bit group is also inverted. Because of this
function, the data in X address H'0 can be always
displayed on the top left of an LCD panel with the
MSB at the far left regardless of the LSI is
positioned with respect to the panel. In this case,
DB7, DB5, DB3 and DB1 are more significant bit
in consecutive two bits.
H'62
H'63
H'00
H'01
SEG1
SEG1
H'27
Display RAM
LCD panel
MSB
(b) MON = 0, ADC = 1 , WLS= 0
(b) MON = 0, ADC = 1, WLS= 0
H'26
LCD drive signal output
X addresses
SEG157
1 1 1 0 0 1 0 0
0 0 0 1 1 0 1 1
D
B
1
D
B
0
SEG158
Rev. 1.1E '99.02.10
D
B
3
D
B
2
DEG159
D
B
5
HD66421
D
B
4
SEG160
D
B
7
H'0
D
B
6
SEG160
Y0
Y1