WIRELESS REMOTE CONTROL for Raymarine ST4000 Autopilot using PIC16F628

I had designed a remote unit for my ST4000+ autopilot. It did prove out the concept and I used it a lot, but it sported an unsightly coil cord (and of course unsightly coil cords have no place on boats) so I decided to build a wireless remote. The system (handheld Tx unit and stationary Rx unit) is based on a pair of microcontrollers and a pair of 433MHz radios.

seatalk_wireless_remote

The keypad/transmitter is on the left. It consists of a PIC16F628 microcontroller, Parallax 433MHz transmitter module ( and antenna, and membrane keypad built into the plastic box. It’s powered by a 9V battery. Power saving firmward allows it to run continuously for several months…there is no power switch. The receiver is on the right (above.) It consists of a Parallax 433MHz receiver module and antenna, PIC16F628 microcontroller, and Seatalk interface components. Schematic and firmware details are below.

seatalk_wireless_remote_schematic

Code:

/****************************************************************************

seatalk_wireless_remote_tx_1.c

This program is a remote control transmitter that sends a RxCx
number in an eight-byte message sentence with checksum.

Message protocol to the wireless receiver
* Each 9600 baud message contains a command and checksum:
   0xff    // wake up the transmitter and receiver
   0xff    // wake up the transmitter and receiver
   0xff    // wake up the transmitter and receiver
   'J'     // character
   'S'     // character
   'F'     // character
   cMsgCode   // which key was pressed
   'J' + 'S' + 'F' + cMsgCode   // equals checksum

                    +5
                    |
                    14
                ----------
      R4 ----6-| B0    A0 |-17-- out to Parallax 433MHz transmitter
      R3 ----7-| B1    A1 |-18-- out to LED
      R2 ----8-| B2       |
      R1 ----9-| B3       |
      C3 ---13-| B7       |
      C2 ---12-| B6       |
      C1 ---11-| B5       |
               |          |
 10MHz XTAL-15-|  16F628  |
       XTAL-16-|          |
                ----------
                     5
                     |
                    Gnd

          KEYBOARD ASSIGNMENTS
            C1      C2      C3
        +------------------------+
    R1  |      (cable here)      |
        |                        |
    R2  |                        |
        |                        |
    R3  |                        |
        |                        |
    R4  |                        |
        +------------------------+

***************************************************************************/

For more detail: WIRELESS REMOTE CONTROL for Raymarine ST4000 Autopilot using PIC16F628

About The Author

Ibrar Ayyub

I am an experienced technical writer with a Master's degree in computer science from BZU Multan University. I have written for various industries, mainly home automation and engineering. My writing style is clear and simple, and I am skilled in using infographics and diagrams. I am a great researcher and am able to present information in a well-organized and logical manner.

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