In our previous discussion on the RF Remote Control Circuit for Home Appliances, we explored the concept of controlling household devices through radio frequency communication. Now, let’s delve into the implementation of an FM remote encoder and decoder circuit using the RF600E and RF600D ICs. This combination of encoder and decoder ICs ensures highly secure communication and operates within a voltage range of 2 to 6.6 volts DC.
In this system, we utilize Frequency Modulation (FM) for transmission. When a push button is pressed, it triggers the generation of a specific code in the transmitter section. Here, an encoder is employed to convert parallel data into serial data. The FM transmitter module then receives this serial data and transmits it. On the receiving end, the FM receiver module captures the serial data and feeds it into the decoder, which generates the corresponding output.
- FM Remote Encoder and Decoder Circuit Diagram:
- Transmitter Section:
- Receiver Section:
- FM Remote Encoder/Decoder Circuit Design:
- Transmitter Section:
- Receiver Section:
- How to Operate FM Remote Encoder and Decoder Circuit?
- FM Remote Encoder/Decoder Circuit Advantages:
- FM Remote Encoder/Decoder Circuit Applications:
- Circuit Limitation:
FM Remote Encoder and Decoder Circuit Diagram:
- RF600E encoder
- FM Transmitter module
- 4 push buttons
- Bc848 Transistor
- Resistors – 2.2k, 10k
- RF600D Decoder
- FM Receiver module
- Slide switch
- Push button
- Red LED
- Resistors – 1k(2), 15k, 22k
FM Remote Encoder/Decoder Circuit Design:
The circuit primarily comprises two distinct sections: the transmitter section, responsible for transmitting remote data, and the receiver section, designed to receive this data.
This section features the RF600E encoder, an FM transmitter module, four switches, and an LED. The parallel data is generated using four push buttons. When you press a push button, the corresponding code is generated at the encoder’s 6th pin. The LED connected to the encoder’s 7th pin indicates the signal transmission.
The encoder and decoder ICs employ the balanced Manchester encoded data protocol for transmission. To utilize this encoder IC as a transmitter, you only need a few additional components. The transmission is fully automatic and doesn’t require human intervention. The data format includes a preamble, header, encrypted data, and a CRC bit, resulting in a packet size of 67 bits in this configuration.
Low Battery Warning:
For each action, this encoder IC reads the battery status. The flag bit is sent to the decoder IC if the voltage is less than 3.8 volts.
|1||S0||Input data pin0|
|2||S1||Input data pin1|
|3||S2||Input data pin2|
|4||S3||Input data pin3|
|5||Vss||Ground reference connection|
|6||OP||Data output pin|
|7||LED||Cathode connection for driving LED during the transmission|
|8||Vcc||Supply voltage pin|
The receiver section comprises the RF600D decoder and its associated components. The digital output pins, namely 17, 18, 1, and 2, are linked to the input switches. Pressing a push button causes the corresponding pin on the decoder to go low. The SPDT switch serves to choose between digital functions, either latching or memory. Furthermore, there is a learn switch used to activate the learn mode on the decoder IC.
Protocol data is sent serially as a stream of ASCII characters with a baud rate of 9600 bits per second in this RF chipset. When it comes to the frame format, there are eight data bits and one stop bit.
|1||OP3||Out||Data output pin|
|2||OP4||Out||Data output pin|
|3||LB||Out||Pin goes low, when battery is low|
|4||Vcc||In||Supply voltage pin|
|6||ECS||Out||Connected to EEPROM CS pin|
|7||ECLK||Out||Connected to EEPROM CLK pin|
|8||EDAT||I/0||connected to EEPROM DATA PIN|
|10||LRN||In||learn/erase switch and status LED drive|
|11||SD1||Out||serial data output|
|12||LKIN||In||Option Link Input for Momentary or Latched outputs|
|13||SLEEP||In||1 = Run, 0 = Sleep Mode|
|14||Vcc||In||Positive supply voltage pin|
|17||OP1||Out||Data output pin|
|18||OP2||Out||Data output pin|
How to Operate FM Remote Encoder and Decoder Circuit?
- Give the connections as per the circuit diagram.
- Connect the LED’s at the decoder outputs.
- Apply 5V supply to the both transmitter and receiver sections.
- Initially all the LED’s will glow.
- Now press the first button at transmitter section, you can observe that first LED will off at decoder section. In the same way for each switch at transmitter the corresponding LED at receiver will off.
- Switch off the power supply for both transmitter and receiver sections.
FM Remote Encoder/Decoder Circuit Advantages:
- Stand alone operation
- LED indication of signal transmission
- Battery low indication
- Manchester modulation
- Sleep mode.
FM Remote Encoder/Decoder Circuit Applications:
- Used in general purpose Remote control applications
- Used in burglar alarm systems
- used in automotive systems
- Used in Electronic door locks
- This circuit is theoretical and may require some practical changes.