Principles Of Operation - Renesas H8S Series User Manual

3.

Principles of Operation

(1) Hardware Settings
(a) LCD Drive Power Supply Settings
The H8S/2268 supports use of its built-in power supply circuit, or use of an external power supply circuit, as the
LCD drive power supply. If an external power supply circuit is used as the LCD drive power supply, connect the
V1 pin to the external power supply.
(b) Triple Step-up Voltage Circuit
The H8S/2268 uses a triple step-up voltage circuit so that a voltage three times the LCD input reference voltage
from the V3 pin can be used to drive the LCD. In this sample task operation of the triple step-up voltage circuit
is turned off (the SUPS bit = 0).
(2) Software Settings
The software settings for implementing LCD display are described below.
(a) Selecting the Duty Cycle and Common Function
The DTS1 and DTS0 bits are used to select the duty cycle setting from among static mode, 1/2 duty, 1/3 duty,
and 1/4 duty. The CMX bit is used to select the common double-buffering function.
(b) Selecting the Segment Drivers
The SGS3 to SGS0 bits are used to select the segment drivers to be used.
(c) Selecting the Frame Frequency
The CKS3 to CKS0 bits are used to select the frame frequency. Select a frame frequency that matches the
specifications of the LCD module used.
(d) Selecting A Waveform or B Waveform
The LCDAB bit is used to select the A waveform or the B waveform as the LCD waveform.
(e) Selecting the LCD Drive Power Supply
The SUPS bit can be used to select the power supply if the internal power supply circuit is used. To use an
external power supply circuit, select V
bit.
REJ06B0486-0100/Rev.1.00
LCD Display Using 1/4 Duty Drive (LCD Controller/Driver)
using SUPS and turn the LCD drive power supply off using the PSW
CC
March 2005
H8S Family
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