HD404328 Datasheet, PDF (61/96 Pages) Hitachi Semiconductor – 4 BIT SINGLE CHIP MICROCOMPUTER

HD404328 Series
LCD Controller/Driver
The MCU has an LCD controller and driver which drive four common signal pins and 24 segment pins.
The controller consists of a RAM area in which display data is stored, a display control register (LCR), and
a duty cycle/clock control register (LMR), as shown in figures 37 and 38.
Four duty cycles and the LCD clock are program-controllable, and a built-in dual-port RAM ensures that
display data can be automatically transmitted to the segment signal pins without program intervention. If a
32-kHz oscillation clock is selected as the LCD clock source, the LCD can be used even in watch mode, in
which the system clock stops.
V_CC
Power switch
V1
*
V2
*
V3
*
GND
LCD
power
control
circuit
Display on/off
LCD
common
driver
LCD clock
COM1
COM2
COM3
COM4
LCD output
register
(LOR: $015)
4
1
2
Display control
register
(LCR: $013)
LCD duty cycle/
clock control
register
(LMR: $014)
2
2
$050
Display
area
(dual-port
RAM)
$067
LCD
segment
driver
Segment/
R2–R5
port
multiplexer
R2 ₀ /SEG1
R2 ₁ /SEG2
R5₃ /SEG16
SEG17
RAM area
Duty cycle selection
Clock selection
SEG24
LCD clock
3
Divided system
clock output
1
Divided 32-kHz
clock output
Note: * HD404324U, HD404326U, HD404328U and HD4074329U require external LCD voltage division resistors.
LCD: Liquid crystal display
Figure 37 Block Diagram of LCD Controller/Driver
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