HD404829R Datasheet, PDF (100/149 Pages) Renesas Technology Corp – AS Microcomputer Incorporating a LCD controller/Driver Circuit

HD404829R Series
LCD Controller/Driver
The MCU has an LCD controller and driver which drive 4 common signal pins and 52 segment pins. The
controller consists of a RAM area in which display data is stored, a display control register (LCR: $01B),
and a duty-cycle/clock-control register (LMR: $01C) (figure 87).
Four duty cycles and the LCD clock are programmable, 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 even be used in watch mode, in which
the system clock stops.
COM1
COM2
COM3
COM4
SEG1
SEG4
SEG5
SEG8
SEG9
SEG20
SEG21
SEG52
Note:
V_CC
Internal LCD power supply switch
V₁
Common
signal
output
circuit
V₂
V₃
GND
Pin control
4
4
Segment
signal
output
circuit
3
Display
control
2
Display data
52
2
Clock
Duty
selection
LCD control
register
(LCR)
LCD output
register 1
(LOR1)
LCD output
register 2
(LOR2)
LCD output
register 3
(LOR3)
Dual-port
display RAM
(52 digits)
Selector
2
LCD mode
register
(LMR)
Pin function switching circuit
Figure 87 LCD Controller/Driver Block Diagram
Data bus
Clock line
Signal line
98