HT12E and HT12D (pairs) are Encoder Decoder ICs manufactured for Remote Control Applications.
These ICs can be used with RF Transmitter and Receiver modules.
By using the paired HT12E encoder and HT12D decoder we can transmit 12 bits of parallel data serially.
HT12D simply converts serial data to its input (may be received through RF receiver) to 12 bit parallel data.
These 12 bit parallel data is divided into 8 address bits and 4 data bits.
Using 8 address bits we can provide 8-bit security code for 4-bit data and can be used to address multiple receivers by using the same transmitter.