hd66421 Renesas Electronics Corporation., hd66421 Datasheet - Page 36

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

Internal Registers
The HD66421 has one index register and 18 data
registers,
asynchronously with the internal clock. All the
registers except the display memory access
register are write-only. Accessing unused bits or
addresses affects nothing; unused bits should be
set to 0 when written to.
Index
(figure 32) selects one of 18 data registers. The
index register itself is selected when both the
CS and RS signals are low. Data bits 7 to 5
are unused; they should be set to 0 when
written to.
Control Register 1 (R0): Control register 1
(figure 33) controls general operations of the
HD66421. Each bit has its own function as
described below.
RMW bit
RMW = l: Read-modify-write mode
RMW = 0: Address is incremented after both
DISP bit
DISP = 1: Display on
DISP = 0: Display off (all LCD driver output
Preliminary
Register
pins output VLCD level)
Address is incremented only after
write access
write and read accesses
all
of
Set value
Set value
(IR):
Data bit
Data bit
which
The
can
RMW DISP
7
7
index
be
Figure 32 Index Register (IR)
Figure 33 Control Register 1 (R0)
6
6
accessed
register
STBY PWR
5
5
36
STBY bit
PWR bit
This bit controls the external power supply for
LCD driving outputs.
AMP bit
REV bit
HOLT bit
ADC bit
STBY = l: Internal operation and oscillation halt;
STBY = 0: Normal operation
PWR = l: Output high level from DCON terminal
PWR = 0: Output low level from DCON terminal
AMP = 1: OP amp enable
AMP = 0: OP amp disable
REV = 1: Reverse display
REV = 0: Normal display
HOLT = l : Internal operation stops
HOLT = 0: Internal operation starts
ADC = l: Data in X address H'0 is output from
ADC = 0: Data in X address H'0 is output from
4
4
AMP
Register number
3
3
SEG160; row signals depend on duty.
SEG1; row signals are scanned from
COM1.
display off
REV
2
2
HOLT ADC
1
1
0
Rev. 1.1E '99.02.10
0
HD66421