HT1647_05 データシートの表示（PDF） - Holtek Semiconductor
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HT1647_05 Datasheet PDF : 17 Pages
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SEG 0
SEG 1
SEG 2
SEG 3
C O M 15
C O M 14
7
15
23
31
COM 1
COM 0
HT1647
0
8
16
24
A d d r e s s 9 B its
(A 8 , A 7 , ...., A 0 )
S E G 63
511
504
A ddr
D3
D2
D1
D 0 D a ta
A ddr
D3
D2
D1
D 0 D a ta
D a ta 4 B its
(D 3 , D 2 , D 1 , D 0 )
: T w o b its o f R A M m a p to L C D 's o n e p ix e l a n d d e c id e 4 - le v e l g r a y s c a le
o r 4 - c o lo r d is p la y c o n c u r r e n tly .
Display Memory - RAM Structure
Gray Scale Level Decision
HT1647 uses PWM technique to provide 4-level gray
scale display. Two bits of RAM data code ((D3, D2) or
(D1, D0)) decide one pixel level of LCDs, level 1~level
divided by 4. Every level must be defined as one kind of
gray scale by PWM data (namely B4~B0) previously.
RAM Data Code
(D3, D2) or (D1, D0)
Choice Gray Scale Level
(1, 1)
Level 1
(1, 0)
Level 2
(0, 1)
Level 3
(0, 0)
Level 4
RAM Data Defined Gray Scale Level
Frame Frequency
HT1647 provides two kinds of frame frequency option
by command code; 89Hz and 170Hz respectively.
FRAME 89Hz provides 89Hz frame frequency and ac-
tive segment signal width can be divided into 24 sec-
tions concurrently. FRAME 170Hz provides 170Hz
frame frequency and active segment signal width can be
divided into 13 sections concurrently. The 24 sections
display a particularly gray scale more than the 13 sec-
tions by PWM data. The default is FRAME 89Hz.
Gray Scale Display
If the user choose 89Hz frame frequency, a max. of 24
sections can be programmed to suit a satisfactory gray
scale in every level. Similarly, if the user choose 170Hz
frame frequency, a max. of 13 sections can be pro-
grammed to suit a satisfactory gray scale in every level.
HT1647 provides 5-bit PWM data to control the length of
the section. In other words, a max. Of 24 gray scales are
generated by 5-bit binary PWM data. At FRAME 89Hz
mode, the HT1647 only provides a max. of 24 adjust-
able gray scales although 32 is the expressed max.
value by 5 bits binary code. When 5 bits binary code
value is more than 23, the PWM control circuit uniformly
regards 23. To increase PWM data indicates to increase
the length of the active segment signal. The varied
length of the active segment signal displays varied gray
scale in TN-type, STN-type LCDs (refer to table 1). Simi-
larly, it displays varied color in ECB-type LCDs. The
color display is derived from ECB-type LCD specifica-
tion. At FRAME 170Hz mode, the HT1647 only provides
a max. of 13 adjustable gray scales although 32 is the
expressed max. value by 5 bits binary code. When the 5
bits binary code value is more than 12, the PWM control
circuit uniformly regards 12. The user must appoint four
kinds of PWM data to four kinds of different gray scale
level by commanding PWM data (refer to table 2).
Name
FRAME 170Hz
FRAME 89Hz
Command Code
X100-0001-1000-XXXX
X100-0001-1101-XXXX
Function
Select 170Hz frame frequency and active segment signal
width can be divided into 13 sections
Select 89Hz frame frequency and active segment signal width
can be divided into 24 sections
Frame Frequency Selection Command Code
Rev. 1.30
8
November 10, 2005
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