Rev. 1.50
14�
����st ��� �01�
Rev. 1.50
149
����st ��� �01�
HT66F0175/HT66F0185
A/D Flash MCU with EEPROM
HT66F0175/HT66F0185
A/D Flash MCU with EEPROM
SCOM/SSEG Function for LCD
The devices have the capability of driving external LCD panels. The common and segment pins
for LCD driving, SCOM0~SCOM5 and SSEG0~SSEG19 or SSEG0~SSEG23, are pin-shared with
certain pins on the I/O ports. The LCD signals, COM and SEG, are generated using the application
program.
LCD Operation
An external LCD panel can be driven using the devices by configuring the I/O pins as common pins
and segment pins. The LCD driver function is controlled using the LCD control registers which in
addition to controlling the overall on/off function also controls the R-type bias current on the SCOM
and SSEG pins. This enables the LCD COM and SEG driver to generate the necessary V
SS
, (1/3)
V
DD
, (2/3)V
DD
and V
DD
voltage levels for LCD 1/3 bias operation.
The LCDEN bit in the SLCDC0 register is the overall master control for the LCD driver. This bit is
used in conjunction with the COMnEN and SEGnEN bits to select which I/O pins are used for LCD
driving. Note that the corresponding Port Control register does not need to first setup the pins as
outputs to enable the LCD driver operation.
V
DD
(�/3) V
DD
(1/3) V
DD
V
DD
LCD
Voltage
Select
Circuit
LCD
COM/SEG
Analog Switch
LCDEN
ISEL[1:0]
COMnEN COMSEGSn
6
6
SEGmEN
FR�ME
SCOM0/SSEG0
SCOM5/SSEG5
SSEG6
SSEGm
m = 19 for HT66F01�5
m = �3 for HT66F01�5
Software Controlled LCD Driver Structure