Functional Description

Operation

The 2

or D8~D11 for the HT12A, active low). This cycle will repeat itself as long as the transmission enable (TE or D8~D11) is

held low. Once the transmission enable returns high the encoder output completes its final cycle and then stops as

shown below.

Information Word

If L/M=1 the device is in the latch mode (for use with the latch type of data decoders). When the transmission enable is re-

moved during a transmission, the DOUT pin outputs a complete word and then stops. On the other hand, if L/M=0 the de-

vice is in the momentary mode (for use with the momentary type of data decoders). When the transmission enable is

removed during a transmission, the DOUT outputs a complete word and then adds 7 words all with the

²1² data code.

An information word consists of 4 periods as illustrated below.

HT12A/HT12E

Rev. 1.10

5

January 24, 2003

4 w o r d s

4 w o r d s

E n c o d e r

D O U T

T r a n s m i t t e d

C o n t i n u o u s l y

< 1 w o r d

T E

Transmission timing for the HT12E

E n c o d e r

D O U T

T r a n s m i t t e d

C o n t i n u o u s l y

< 1 w o r d

D 8 ~ D 1 1

K e y - i n

1 w o r d

w i t h 3 8 k H z c a r r i e r

1 w o r d

Transmission timing for the HT12A (L/M=Floating or VDD)

E n c o d e r

D O U T

T r a n s m i t t e d

C o n t i n u o u s l y

D 8 ~ D 1 1

K e y - i n

1 w o r d

< 1 w o r d

7 w o r d s

1 w o r d

7 w o r d s

( a l l d a t a = 1 )

( a l l d a t a = 1 )

Transmission timing for the HT12A (L/M=VSS)

1 / 3 b i t s y n c . p e r i o d

p i l o t p e r i o d ( 1 2 b i t s )

a d d r e s s c o d e p e r i o d

p e r i o d

d a t a c o d e

Composition of information