HD404818 Datasheet, PDF (64/100 Pages) Hitachi Semiconductor – 16-digit LCD driver

HD404818 Series
LCD Controller/Driver
The MCU contains four common signal pins, the controller, and the driver. The controller and the driver
drive 32 segment signal pins. The controller consists of display data RAM, the LCD control register (LCR),
and the LCD duty-cycle/clock control register (LMR) (figure 34). Four programmable duty cycles and
LCD clocks are available. Since the MCU contains a dual port RAM, display data can be transferred to
segment signal pins automatically without program control. When selecting the 32-kHz oscillation clock as
the LCD clock source, the system allows the LCD to display even in watch mode, in which the system
clock halts.
V_CC
Power switch
V₁
V₂
V₃
GND
LCD
power
supply
control
circuit
Display on/off
2
Display
control
register
LCR: $013
LMR: $014
LCD duty-
cycle/clock
control register
$050
Display
area
(dual port
RAM)
$06F
22
RAM area
Duty selection
Clock selection
LCD
common
driver
COM1
COM2
COM3
COM4
LCD
clock
SEG1
SEG2
LCD
segment
driver
SEG32
LCD
clock
3
1
System clock dividing
output (CL1–CL3)
32-kHz clock dividing
output (CL0)
Figure 34 LCD Controller/Driver Configuration
LCD Data Area and Segment Data ($050 to $06F): Figure 35 shows the configuration of the LCD RAM
area. Each bit of this area, corresponding to four types of duty cycles, can be transmitted to the segment
driver as display data by programming the area corresponding to the duty cycle.
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