Renesas H8S Series User Manual page 7

(3) Functions of LCD Controller/Driver
• LCD port control register (LPCR)
LPCR is an 8-bit readable/writable register that selects the duty cycle, LCD driver, and pin functions.
• LCD control register (LCR)
LCR is an 8-bit readable/writable register that performs LCD drive power supply on/off control, display function
activation control, display data control, and frame frequency selection.
• LCD control register 2 (LCR2)
LCR2 is an 8-bit readable/writable register that controls switching between the A waveform and B waveform,
selects the clock source for the triple step-up voltage circuit, selects the drive power supply, and selects the duty
cycle for periods when the power supply split-resistors are connected to the power supply circuit.
• Segment output pins (SEG40 to SEG1)
These pins are used to drive the LCD segments. All can also function as ports and their settings are programmable.
• Common output pins (COM4 to COM1)
These are the common drive pins for the LCD. In the static mode and with 1/2 duty, these pins can be used in
parallel.
• LCD power supply pins (V1, V2, V3)
These pins are used when the H8S/2268 is connected to a bypass capacitor, and an external power supply is used.
The V3 pin functions as the reference power supply input to the LCD when the triple step-up voltage circuit is used.
• LCD step-up voltage capacitance pins (C1, C2)
These are the capacitance pins for the LCD drive power supply step-up voltage.
• LCD RAM
Used to set the display data. The relationship between LCD RAM and the display segments differs depending on
the duty cycle. After setting the registers required for display, data is written to the portions of LCD RAM
corresponding to the duty cycle using normal RAM instructions. Display begins automatically when the LCD is
powered on. Word- or byte-access instructions may be used for RAM setting.
(4) Connection Diagram
In this sample task an 8-digit 8-segment LCD and 1/4 duty cycle are used for LCD display. A connection diagram
for the segment signals and common signals for the 8-digit 8-segment LCD used in the sample task is shown in
figure 3.
COM1
COM2
COM3
COM4
Figure 3 Connection Diagram for Segment Signals and Common Signals for 8-Digit 8-Segment LCD
REJ06B0486-0100/Rev.1.00
LCD Display Using 1/4 Duty Drive (LCD Controller/Driver)
Used in Sample Task
March 2005
H8S Family
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