BS85B12-3 Datasheet, PDF (149/182 Pages) Holtek Semiconductor Inc – Touch Key Flash Type 8-Bit MCU with LCD/LED Driver

BS85B12-3/BS85C20-3
Touch Key Flash MCU with LCD/LED Driver
The accompanying waveform diagram shows a typical 1/3 Bias LCD waveform generated using the
application program. Note that the depiction of a ²1² in the diagram illustrates an illuminated LCD
pixel. The COM signal polarity generated on pins SCOM0~SCOM3, whether 0 or 1, are generated
using the corresponding I/O data registers, which are bits PB0~PB3 in the PB register.
COM 0
fra m e 0
fra m e 1
fra m e 0
VDD
0
0
0
1
0
0
0
1
1
2 /3 V D D
1 /3 V D D
VSS
COM 1
COM 2
0
0
0
0
0
0
0
1
1
1
0
0
0
0
0
0
1
1
0
0
VDD
2 /3 V D D
1 /3 V D D
VSS
VDD
2 /3 V D D
1 /3 V D D
VSS
COM 3
SEG 0
SEG 1
0
0
0
0
0
0
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
1
0
1
1
1
0
1
0
VDD
2 /3 V D D
1 /3 V D D
VSS
VDD
2 /3 V D D
1 /3 V D D
VSS
VDD
2 /3 V D D
1 /3 V D D
VSS
Note: The logical values shown in the diagram are the PB I/O register values, PB0~PB3.
1/3 Bias LCD Waveform
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 1/3 VDD. The
SEG signal can have a value of VSS, or have a Vbias value of 2/3 VDD.
In Frame 1
In frame 1, the COM signal output can have a value of VSS, have a Vbias value of 2/3 VDD. The SEG
signal can have a value of VDD have a Vbias value of 1/3 VDD.
Rev. 1.00
143
February 1, 2011