HD404629R Datasheet, PDF (106/157 Pages) Renesas Technology Corp – AS Microcomputer Incorporating a DTMF Generator Circuit

HD404629R 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 94).
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
Data bus
Clock line
Signal line
Figure 94 Block Diagram of Liquid Crystal Display Control System
104