HT12E Ver la hoja de datos (PDF) - Holtek Semiconductor

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HT12E

212 Series of Encoders

Holtek Semiconductor 

HT12A/HT12E

Functional Description

Operation

The 212 series of encoders begin a 4-word transmission cycle upon receipt of a transmission enable (TE for the HT12E

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.

TE

E ncoder

DOUT

< 1 w o rd

4 w o rd s

T r a n s m itte d

C o n tin u o u s ly

Transmission timing for the HT12E

4 w o rd s

D 8~D 11

K e y - in

E ncoder

DOUT

< 1 w o rd

1 w o rd

T r a n s m itte d

C o n tin u o u s ly

w ith 3 8 k H z c a r r ie r

1 w o rd

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

D 8~D 11

K e y - in

E ncoder

DOUT

< 1 w o rd

7 w o rd s

1 w o r d ( a ll d a ta = 1 )

T r a n s m itte d

C o n tin u o u s ly

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

( a ll d a ta = 1 )

7 w o rd s

1 w o rd

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.

p ilo t p e r io d ( 1 2 b its )

1 /3 b it s y n c . p e r io d

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

Composition of information

d a ta c o d e

p e r io d

Rev. 1.20

5

February 20, 2009

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