HT12A/HT12E
Address/Data Waveform
Each programmable address/data pin can be externally set to one of the following two logic states as shown below.
f
O
S C
"O n e "
"Z e ro "
A d d re s s /
D a ta B it
Address/Data bit waveform for the HT12E
f
O
S C
"O n e "
D a ta B it
"Z e ro "
D a ta B it
"O n e "
A d d r e s s B it
"Z e ro "
A d d r e s s B it
3 8 k H z
c a r r ie r
Address/Data bit waveform for the HT12A
The address/data bits of the HT12A are transmitted with a 38kHz carrier for infrared remote controller flexibility.
Address/Data Programming (Preset)
The status of each address/data pin can be individually pre-set to logic
²high²
or
²low².
If a transmission-enable signal
is applied, the encoder scans and transmits the status of the 12 bits of address/data serially in the order A0 to AD11 for
the HT12E encoder and A0 to D11 for the HT12A encoder.
During information transmission these bits are transmitted with a preceding synchronization bit. If the trigger signal is
not applied, the chip enters the standby mode and consumes a reduced current of less than 1mA for a supply voltage of
5V.
Usual applications preset the address pins with individual security codes using DIP switches or PCB wiring, while the
data is selected by push buttons or electronic switches.
The following figure shows an application using the HT12E:
O S C 1
O S C 2
D O U T
T r a n s m is s io n
m e d iu m
V D D
A 0
A 1
A 2
A 3
A 4
A 5
A 6
A 7
V S S
T E
A D 8
A D 9 A D 1 0 A D 1 1
V
D D
V S S
Rev. 1.10
6
January 24, 2003
HOLTEK [ HOLTEK SEMICONDUCTOR INC ]
