SN32F280 Series
32-Bit Cortex-M0 Micro-Controller
SONiX TECHNOLOGY CO., LTD
Page 195
Version 1.1
17.4 LCD CHANNEL CONTROL
The LCD includes 4-COM pins, 40-SEG pins and 4-COM/SEG share pins. Each of the LCD channels is shared with
GPIO. If the LCD driver is enabled (LCDEN=1), the 4-COM pins are controlled to LCD COM pin mode, but the 40-SEG
pins are controlled by SEGSEL1 and SEGSEL2 registers.
The COM/SEG share pin will follow the mode selection, to switch the COM or SEG functions. When the COM mode is
selected, the pin will switch to common function, and the segment function will be ignored. Conversely, the segment
function is enabled according to the segment control bit setting.
Each of the LCD channels has a bias switch circuit to select a bias voltage for COM or SEG driving waveform. The bias
voltage is from the LCD bias generator. The bias switch is controlled by LCD COM and SEG output control.
In LCD static mode, the bias switch of COM and SEG pins is disabled. The selected COM and SEG pins switch to be
GPIO output mode and only output 0V and VDD voltage. The LCD COM and SEG output control circuits control the
GPIO output latch of COM and SEG pins directly.
LCDEN
COM
mode
LCD COM
LCD SEG
LCD COM/SEG share
COM0~COM3 SEG0 SEG1
…
SEG30
SEG31
SEG31/
COM7
SEG30/
COM6
SEG29/
COM5
SEG28/
COM4
0
X
GPIO
GPIO GPIO GPIO
GPIO
GPIO
GPIO
GPIO
GPIO
GPIO
1
4
COM
Control by SEGSEL1[31:0]
Control by
SEGSEL1[31]
Control by
SEGSEL1[30]
Control by
SEGSEL1[29]
Control by
SEGSEL1[28]
6
COM5
COM4
7
COM6
8
COM7
When LCDIDLE bit is set, If the LCD driver is disabled (LCDEN=0), all COM pins are controlled to V1 or VDD by LSTC
bit.
LCDEN
LSTC
LCDIDLE
COMn pin
SEGn pin
SEGn enable
COM share
0
0
0
GPIO
GPIO
GPIO
0
0
1
V1
GPIO
V1
0
1
0
GPIO
GPIO
GPIO
0
1
1
VDD
GPIO
VDD
1
0
N/A
LCD COM
LCD SEG
LCD COM
1
1
N/A
LED COM
LED SEG
LED COM