BS85B12-3_12 Datasheet, PDF (154/183 Pages) Holtek Semiconductor Inc – Touch Key Flash Type 8-Bit MCU with LCD/LED Driver

BS85B12-3/BS85C20-3/BS85C20-5
Touch Key Flash MCU with LCD/LED Driver
A cyclic LCD waveform includes two frames, known as Frame 0 and Frame 1 for which the
following offers a functional explanation.
In Frame 0
To select Frame 0 clear the FRAME bit to 0.
In frame 0, the COM signal output can have a value of VDD, or have a Vbias value of 1/3VDD. The
SEG signal can have a value of VSS, or have a Vbias value of 2/3VDD.
In Frame 1
In frame 1, the COM signal output can have a value of VSS, have a Vbias value of 2/3VDD. The SEG
signal can have a value of VDD have a Vbias value of 1/3VDD.
The COM0~COMn waveform is controlled by the application program using the FRAME bit, and the
corresponding I/O data register for the respective COM pin to determine whether the COM0~COMn
output has a value of either VDD, VSS or Vbias. The SEG0~SEGm waveform is controlled in a similar
way using the FRAME bit and the corresponding I/O data register for the respective SEG pin to
determine whether the SEG0~SEGn output has a value of either VDD, VSS or Vbias.
LCD Bias Control
The LCD COM and SEG driver enable a range of selections to be provided to suit the requirement
of the LCD panel which are being used. The bias resistor choice is implemented using the ISEL1
and ISEL0 bits in the LCD control register.
LCD Driver Registers
SLCDC0 Register
Bit
7
6
5
4
3
2
1
0
Name FRAME ISEL1 ISEL0 SLCDEN COM3EN COM2EN COM1EN COM0EN
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
POR
0
0
0
0
0
0
0
0
Bit 7
Bit 6~5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
FRAME: Present Frame output select – Frame 0 or Frame 1
0: Frame 0
1: Frame 1
ISEL1, ISEL0: SCOM and SSEG operating current selection – VDD=5V
0: 25µA
1: 50µA
2: 100µA
3: 200µA
SLCDEN: SCOM and SSEG module on/off control
0: disable
1: enable
The SCOMn and SSEGm lines can be enabled using COMnEN and SEGmEN if
SLCDEN=1. When SLCDEN=0, then the SCOMn and SSEGm outputs will be fixed
at a VDD level.
COM3EN: SCOM3 or other function selection
0: Other function
1: SCOM3
COM2EN: SCOM2 or other function selection
0: Other function
1: SCOM2
COM1EN: SCOM1 or other function selection
0: Other function
1: SCOM1
COM0EN: SCOM0 or other function selection
0: Other function
1: SCOM0
Rev. 1.20
154
August 10, 2012