Scom Function For Lcd; Lcd Ope�Ation - Holtek HT66F20-1 Manual

SCOM Function for LCD

The devices have the capability of driving external LCD panels. The common pins for LCD driving,
SCOM0~SCOM3, are pin shared with certain pin on the PC0~PC1, PC6~PC7 port. The LCD
signals (COM and SEG) are generated using the application program.
LCD Operation
An external LCD panel can be driven using this device by configuring the PC0~PC1, PC6~PC7
pins as common pins and using other output ports lines as segment pins. The LCD driver function
is controlled using the SCOMC register which in addition to controlling the overall on/off function
also controls the bias voltage setup function. This enables the LCD COM driver to generate the
necessary V /2 voltage levels for LCD 1/2 bias operation.
DD
The SCOMEN bit in the SCOMC register is the overall master control for the LCD driver, however
this bit is used in conjunction with the COMnEN bits to select which Port C pins are used for LCD
driving. Note that the Port Control register does not need to first setup the pins as outputs to enable
the LCD driver operation.
SCOMEN
0
1
1
Rev. 1.40
HT66F20-1/HT66F30-1/HT68F20-1/HT68F30-1
Flash MCU with EEPROM
V
D D
S C O M o p e r a t i n g c u r r e n t
V / 2
D D
C O M n E N
S C O M E N
LCD COM Bias
COMnEN Pin Function
X
0
1 SCOMn
Output Control
180
S C O M 0 ~
S C O M 3
O/P Level
I/O 0 o� 1
I/O 0 o� 1
V /�
DD
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