LC4 RF Receiver / Quad Relay Board

Figure #1
Assembled LC4 Receiver/Relay Board

Learn how to decode transmitters using the 4-bit Holtek HT12E encoder, Linx Technologies CMD-HHLR-433 with 8-bit Holtek HT640 encoder, make your own 4-bit encoder & decoder ICs, send/receive wireless serial data between two 8-pin PIC microcontrollers, create an 8-pin serial encoder IC to replace the Holtek 8-bit HT640, work with the Linx long-range LR series RF modules, and even work with the Microchip rfPIC development kits.

The LC4 receiver doubles as a development platform for the Linx long range LR receivers, or as a stand alone remote control solution with many flexible options. Together with the code examples we provide for the PicBasic Pro compiler, this can be one very flexible remote control system.

The LC4 is available as a bare circuit board, with a pre-soldered LR receiver module, as a full kit, and a full kit with PicBasic Pro code examples on CD-ROM for several wireless remote control applications.

Options:

1. A bare unpopulated circuit board.

2. The circuit board with an LR receiver module pre-installed. Your choice of 315, 418 or 434MHz receivers.

3. A full kit with RXM-433-LR receiver installed, and all parts to assemble the board as shown in figure #1.

4. The #3 full kit option + a CD-ROM containing code examples in PicBasic Pro.

PicBasic Pro Code Examples On CD-ROM: 3 NEW bonus code examples added 10/17/2007

1. Using the 8-pin PIC12F635 to decode the Holtek 4-bit HT12E encoder. Including address learning
   + storage of the learned address in onboard EEPROM.

2. Using the 8-pin PIC12F683 to decode the CMD-HHLR-433 transmitter with 8-bit HT640 encoder. Including
   address learning + storage of the learned address in onboard EEPROM.

3. How to create your own 4-bit momentary encoder/decoder IC's with the 12F635. This example includes
   RF wireless serial communications for the encode/decode functions, with the encoder entering low-power
   sleep mode until a button is pressed. The encoder circuit is shown below in figure #2.

4. NEW We're giving you the code for creating our 8-pin serial encoder IC to replace the Holtek 8-bit HT640 encoder. Download the ENC-S40 data sheet HERE Now you can control the LC4 relay board from your PC serial port.

5. NEW PicBasic Pro transmit & receive code examples for working with the Microchip rfPIC Development Kit 1 based on the rfPIC12F675 and rfRXD0420/0920 devices.

Figure #2
Custom Encoder IC With The PIC12F635

Mechanical or Solid State Relays:

The full kit versions include 4 x 10 amp mechanical relays. However, the LC4 can be easily configured for digital outputs with status LEDs to indicate when an output is on or off.

Figure #3 shows how to install jumpers for digital control outputs. With the relays and relay diodes not installed, LEDs can be mounted in the pads just outside the relay diode pads. The LED cathode is to the left. The anode is to the right. Series limiting resistors for each LED are installed on the left. The LEDs provide visual ON/OFF status indicators for each digital control output.

Figure #3
Wired For Solid State Relays

Switched power from the drive transistors on the LC4 board is now routed to the screw terminals with short jumper wires. This allows for control of external hardware like solid state relays, buzzers, and other hardware that can operate from the LC4 boards DC power supply.

As shown in Figure #3, +/- DC polarity markings have been added to the LC4 board silkscreen for easy identification when the relays are not installed. The left screw terminal for each digital output is switched ground from the NPN low-side drivers on the board. The right screw terminal for each output is connected directly to positive voltage from the LC4 board power supply.

Figure #4
LC4 Relay Board Schematic

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