HT16512
Functional Description
Display RAM and display mode
The static display RAM is organized into 22´8
bits and stores the data transmitted from an ex-
ternal device to the HT16512 through a serial
interface. The contents of the RAM are directly
mapped to the contents of the VFD driver. Data
in the RAM can be accessed through the data
setting, address setting and display control
commands. It is assigned addresses in 8-bit
unit as follows:
S 0
~
S 3
0 H
2 H
4 H
6 H
8 H
A H
C H
E H
0 H
2 H
4 H
S 4
~
S 7 S 8
~
A d d re s s : 0
0
0
0
0
0
0
0
1
1
1
S 1 1
0
0
0
0
0
0
0
0
1
1
1
D
F
1
3
5
1
3
5
7
9
B
S 1 2
H
H
H
H
H
H
H
H
H
H
H
~
S 1 5
D ig
D ig
D ig
D ig
D ig
D ig
D ig
D ig
D ig
D ig
D ig
it0
it1
it2
it3
it4
it5
it6
it7
it8
it9
it1 0
K 0 ~ K 3 a r e sa mpl ed b y s tro be s i g na l
S0/K0~S5/K5 and latched into the register.
The key matrix is made up of a 6´4 matrix, as
shown below.
S 0 /K 0
K 0
K 1
K 2
K 3
D e ta il
S 1 /K 1
S 2 /K 2
S 3 /K 3
S 4 /K 4
S 5 /K 5
K e y m a tr ix
The data of each key is stored as illustrated be-
low, and is read with the read command, start-
ing from the least significant bit.
K 0 ~ K 3
S 0 /K 0
S 2 /K 2
S 4 /K 4
K 0 ~ K 3
S 1 /K 1
S 3 /K 3
S 5 /K 5
R e a d in g la s t
R e a d in g fir s t
b 0 b 1 b 2 b 3 b 4 b 5 b 6 b 7
b 0 b 1 b 2 b 3 b 4 b 5 b 6 b 7
Dimming control
HT16512 porvides 8-step dimmer function on
display by controlling the 3-bit binary com-
mand code. The full pulse width of grid signal is
divides into 16 uniform sections by PWM (pulse
width modulation) technology.
The 16 uniform sections available form 8 steps
dimmer via 3-bit binary code. The 8-step dim-
mer includes 1/16, 2/16, 4/16, 10/16, 11/16,
12/16, 13/16 and 14/16. The 1/16 pulse width in-
dicates minimum lightness. The 14/16 pulse
width represents maximum lightness. (Refer to
the display control command).
Key matrix and key-input data storage RAM
The key matrix scans the series key states at
e ac h lev el of t he key str ob e si gna l
(S0/K0~S5/K5) output of the HT16512. The key
strobe signal outputs are time-multiplexed sig-
nals from S0/K0~S5/K5. The states of inputs
b 0 b 1 b 2 b 3 b 4 b 5 b 6 b 7
LED port
The LED port belongs to the CMOS output con-
figuration.
Data is written to the LED port with the write
command, starting from the least port¢s least
significant bit. In our application (see applica-
tion circuits), the user adopts an internal
NMOS device to a driver LED component by
connecting VDD. When a bit of this port is 0,
the corresponding LED lights; when the bit is 1,
the LED turns off. The data of bits 5 through 8
are ignored.
M S B
b 3
b 2
b 1
L S B
b 0
L E D
L E D
L E D
L E D
1
2
3
0
D o n 't c a r e
6
December 24, 1999
HOLTEK [ HOLTEK SEMICONDUCTOR INC ]
