HT12F(1999) 데이터 시트보기 (PDF) - Holtek Semiconductor
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HT12F Datasheet PDF : 9 Pages
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Functional Description
Operation
The 212 series of decoders provides various com-
binations of addresses and data pins in differ-
ent packages so as to pair with the 212 series of
encoders.
The decoders receive data that are transmitted
by an encoder and interpret the first N bits of
code period as addresses and the last 12-N bits
as data, where N is the address code number. A
signal on the DIN pin activates the oscillator
which in turn decodes the incoming address
and data. The decoders will then check the re-
ceived address three times continuously. If the
received address codes all match the contents of
the decoder¢s local address, the 12-N bits of
data are decoded to activate the output pins
and the VT pin is set high to indicate a valid
transmission. This will last unless the address
code is incorrect or no signal is received.
The output of the VT pin is high only when the
transmission is valid. Otherwise it is always
low.
Output type
Of the 212 series of decoders, the HT12F has no
data output pin but its VT pin can be used as a
momentary data output. The HT12D, on the
other hand, provides 4 latch type data pins
whose data remain unchanged until new data
are received.
Part Data Address Output Operating
No. Pins Pins Type Voltage
HT12D 4
8
Latch 2.4V~12V
HT12F 0
12
¾ 2.4V~12V
212 Series of Decoders
Flowchart
The oscillator is disabled in the standby state
and activated when a logic ²high² signal applies
to the DIN pin. That is to say, the DIN should be
kept low if there is no signal input.
P ow eron
S ta n d b y m o d e
No
C o d e in ?
Y es
D is a b le V T &
ig n o r e th e r e s t o f
th is w o r d
A d d r e s s b its
No
m a tc h e d ?
Y es
S to re d a ta
M a tc h
p r e v io u s s to r e d
No
d a ta ?
Y es
No
3 tim e s
o f c h e c k in g
c o m p le te d ?
Y es
L a tc h d a ta
to o u tp u t &
a c tiv a te V T
No
A d d re s s o r
d a ta e rro r ?
Y es
5
July 12, 1999
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