HD66421TB0 HITACHI [Hitachi Semiconductor], HD66421TB0 Datasheet - Page 36

• Manufacturer Part Number: HD66421TB0
• Description: (RAM-Provided 160 Channel 4-Level Grey Scale Driver for Dot Matrix Graphics LCD)
• Manufacturer: HITACHI [Hitachi Semiconductor]

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