The 212 decoders are a series of CMOS LSIs for
remote control system applications. They are
paired with Holteks 212 series of encoders (refer
to the encoder/decoder cross reference table).
For proper operation, a pair of
encoder/decoder with the same number of addresses
and data format should be chosen.
The decoders receive serial addresses and data
from a programmed 212 series of encoders that
are transmitted by a carrier using an RF or an
IR transmission medium. They compare the serial
input data three times continuously with
their local addresses. If no error or unmatched
codes are found, the input data codes are decoded
and then transferred to the output pins.
The VT pin also goes high to indicate a valid
The 212 series of decoders are capable of decoding
informations that consist of N bits of address
and 12N bits of data. Of this series, the
HT12D is arranged to provide 8 address bits
and 4 data bits, and HT12F is used to decode 12
bits of address information.