We have already studied how to control the home appliances using RF communication in the post-RF Remote Control Circuit for Home Appliances. Now let us see how to design FM remote encoder and decoder circuit using RF600E and RF600D ICs. This pair of encoder and decoder ICs establishes communication with high-level security. The operating voltage of these ICs is from 2V to 6.6V DC.

This system uses FM (Frequency Modulation) for transmission. If you press any push button then the corresponding code is generated at the transmission section. Here encoder is used to convert parallel data to serial. This serial data is given to the FM Tx module to transmit. FM Rx module receives this serial data and fed to the decoder to produce the corresponding output.

FM Remote Encoder and Decoder Circuit Diagram:

Transmitter Section:

FM Remote Encoder and Decoder Circuit - Transmitter Section

FM Remote Encoder and Decoder Circuit – Transmitter Section

Circuit Components:

  • RF600E encoder
  • FM Transmitter module
  • 4 push buttons
  • Bc848 Transistor
  • Led
  •  Resistors – 2.2k, 10k

Receiver Section:

FM Remote Encoder and Decoder Circuit - Receiver Section

FM Remote Encoder and Decoder Circuit – Receiver Section

Circuit Components:

  • RF600D Decoder
  • FM Receiver module
  • Slide switch
  • Push button
  • Red LED
  • Resistors – 1k(2), 15k, 22k

FM Remote Encoder/Decoder Circuit Design:

The circuit mainly consists of two sections, one is Transmitter section used t transmit the remote data and other is Receiver section used to receive the data.

Transmitter Section:

This section consists of RF600E encoder, FM transmitter module, four switches and LED. Four push buttons are used to generate parallel data. If you press any push button, the corresponding code is generated at the 6th pin of an encoder. Here the LED which is connected to the 7th pin of an encoder is used for indicating the signal transmission.

RF600E Encoder:

This pair of encoder and decoder ICs uses balanced Manchester encoded data protocol for transmission. This encoder IC requires just fewer components to use it as a transmitter. The transmission is automatic there is no need for human intervention.

The data format includes a pre-amble, header, encrypted data followed by CRC bit. Here the packet size is 67 bits.

Low Battery Indication:

This encoder IC reads the battery status for each operation. If the voltage is below 3.8 volts then the flag bit is transmitted to the decoder IC.

Pin Configuration:

Pin No.
Name
Description
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
Receiver Section:

The receiver section consists of RF600D decoder and its associated components. Pins 17, 18, 1 and 2 are the digital output pins corresponding to the input switches. If you press any push button, then the corresponding pin at the decoder becomes low. Here SPDT switch is used to select latching or memory digital function. The learn switch is used to enter the decoder IC into the “learn mode”.

RF600D Decoder:

In this RF chipset, protocol data is sent serially as a stream of ASCII characters with a baud rate of 9600 bits per second. While coming to the frame format 8 data bits with one stop bit.

Pin Configuration:

Pin No.
Name
Input/Output
Description
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
5
Vss
In
Ground 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
9
IN
In
Data input
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
15
Unused
N/A
no connection
16
Unused
N/A
no connection
17
OP1
Out
Data output pin
18
OP2
Out
Data output pin

How to Operate FM Remote Encoder and Decoder Circuit?

  1. Give the connections as per the circuit diagram.
  2. Connect the LED’s at the decoder outputs.
  3. Apply 5V supply to both transmitter and receiver sections.
  4. Initially, all the LED’s will glow.
  5. Now press the first button at the transmitter section, you can observe that first LED will off at decoder section. In the same way for each switch at the transmitter, the corresponding LED at receiver will off.
  6. Switch off the power supply for both transmitter and receiver sections.

FM Remote Encoder/Decoder Circuit Advantages:

  1. Stand-alone operation
  2. LED indication of signal transmission
  3. Battery low indication
  4. Manchester modulation
  5. 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
Circuit Limitation:
  • This circuit is theoretical and may require some practical changes.

LEAVE A REPLY

Please enter your comment!
Please enter your name here