Rev. 1.10
174
October 23, 2020
Rev. 1.10
175
October 23, 2020
BC66F5652
2.4GHz RF Transceiver A/D Flash MCU
BC66F5652
2.4GHz RF Transceiver A/D Flash MCU
SCOM/SSEG Function for LCD
The device has the capability of driving external LCD panels. The common and segment pins for
LCD driving, SCOM0~SCOM17, SSEG0~SSEG17 and SSEG22~SSEG25, 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 device 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 bias voltage setup function. 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 corresponding pin-shared function selection 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
(2/3) V
DD
(1/3) V
DD
V
DD
LCD
Voltage
Select
Circuit
LCD
COM/SEG
Analog
Switch
LCDEN
ISEL[1:0]
FRAME
SCOM0/SSEG0
SCOM17/SSEG17
SSEG22
SSEG25
Software Controlled LCD Driver Structure
LCD Frames
A cyclic LCD waveform includes two frames known as Frame 0 and Frame 1 for which the
following offers a functional explanation.
Frame 0
To select Frame 0, clear the FRAME bit in the SLCDC0 register to 0.
In Frame 0, the COM signal output can have a value of V
DD
or a V
BIAS
value of (1/3)×V
DD
. The SEG
signal output can have a value of V
SS
or a V
BIAS
value of (2/3)×V
DD
.
Frame 1
To select Frame 1, set the FRAME bit in the SLCDC0 register to 1.
In Frame 1, the COM signal output can have a value of V
SS
or a V
BIAS
value of (2/3)×V
DD
. The SEG