Controlling appliances by RF communication using HT12E & HT12D

The main objective of this project is to learn wireless communication by using HT12E (ENCODER) and HT12D (DECODER) and a pair of RF modules of 433 MHz. After doing this project you will be able to
1)  Control any 4 loads by using wireless remote without any WIFI or Blue tooth or internet
2)  Set security lock to your remote such that the loads are controlled by your remote only but not by any other remote

By using the paired HT12E encoder and HT12D decoder we can easily transmit and receive 12 bits of parallel data serially. HT12E simply converts 12 bit parallel data in to serial output which can be transmitted through a RF transmitter. These 12 bit parallel data is divided in to 8 address bits and 4 data bits. By using these address pins we can provide 8 bit security code for data transmission and multiple receivers may be addressed using the same transmitter
 

HT12E Pins

• VCC (18th PIN) - 5 Volts supply positive terminal is connected to this pin
• GND (9th PIN) - This pin is connected to ground
• OSC1 (16th PIN) and OSC2 (15th PIN) are used to connect external resistor (47Kilo Ohms) for internal oscillator of HT12E. OSC1 is the oscillator input pin and OSC2 is the oscillator output pin
• A0 – A7 (PIN 1 to PIN 8) are the address input pins. Status of these pins should match with status of address pins in HT12D  to receive the data. Often these pins can be connected to VCC or left open.
• TE (14th PIN) is used for enabling the transmission and is an active low input.
• AD0 – AD3 (PIN 10 to PIN 13) are the input data pins. These pins can be connected to VCC or may left open for sending LOW and HIGH respectively.
• DOUT (17th PIN) is the serial data output pin which is connected to RF transmitter input

HT12D Pins

• VCC (18th PIN) - 5 Volts supply positive terminal is connected to this pin
• GND (9th PIN) - This pin is connected to ground
• OSC1 (16th PIN) and OSC2 (15th PIN) are used to connect external resistor (47Kilo Ohms) for internal oscillator of HT12D. OSC1 is the oscillator input pin and OSC2 is the oscillator output pin
• A0 – A7 (PIN 1 to PIN 8) are the address input pins. Status of these pins should match with status of address pin in HT12E (used in transmitter) to receive the data. Often these pins can be connected to VCC or left open.
• DIN (14th PIN) is the serial data input pin and can be connected to a RF receiver output
• D0 – D3 (PIN 10 to PIN 13) are the data output pins. Status of these pins can be VCC or ground depending upon the received serial data through pin DIN
• VT (PIN 17) stand for Valid Transmission. This output pin will be HIGH when valid data is available at D8 – D11 data output pins.

Here Address bits A0 to A7 on both the Encoder and Decoder IC can be grounded. This means that they are both kept at address 0b00000000. This way they both share the same address and they will act as a pair.