How to build DIY Arduino Transmitter OpenTx firmware

        Instruction "How to build  DIY Arduino Transmitter OpenTx firmware" will describe how to build 2.4G 8-channel DIY transmitter using MEGA2560 Arduino controller installing OpenTx firmware which similar to commercial transmitter in the market.       

       The Arduino MEGA2560 will produce traditional PPM signal to send to RF module that can  communicate to general transmitter modules like Frsky,Flysky,Orange,..etc.
        Difficulty : Hard
Materials
1. 1 - Arduino controller - MEGA2560 Core











2. 1 - 128x64 LCD display  12864ZW with ST7920 controller

3. 1 - Old RC transmitter body

4. Joy stick gimbals.(mode1,mode2)

5. Push buttons

6. Capacitors - See detail in BOM

7. Diode 1N4007

8. 1 - 7805 IC Regulator 5V.

9. Female pin header

10. Double rows female pin header

11.Single row male pin header

12.Single row long male pin header

13. Double rows male pin header

14. 1 - LED 5 mm.

15. Resistors

16. Ribbon wires.

17. Male JST Battery Pigtail

18. Heat shrink tube 1.5 - 10 mm.

19. Velcro tape

20. 1 - PCB.DIY. circuit board

21. Battery Lipo 7.4V.1000 mAh (2cells)

22. Electrical 26 AWG wires

23. 1 - Piezo speaker

24. 1 - Transmitter module.(PPM)

25. 1 - Card reader Arduino

26. 1 - SD card

27. Rotary Potentiometer B10K

Tools

1. Soldering gun

2. Soldering wire

3. Soldering paste

4. Screw driver

5. Plier

6. Hot glue gun

7. Epoxy glue

8. Two sides glue tape

9. Plastic cutter

10. Electrical drill

DIY PCB building

1.Installing electronic parts on DIY PCB according to electrical circuit diagram.(see in Github)
2.Install switches,joy stick gimbals,push buttons on transmitter body.

3.Wiring and connecting PCB - MEGA2560 - Gimbals - Switches - Push buttons according to circuit diagram.

Firmware installation (can do before hardware installation)

1.Downloading software OpenTx companion2.2.x from OpenTx website.

2.Installing OpenTx companion on PC.

3.Running OpenTx companion,downloading firmware by using OpenTx companion.

   3.1 Edit setting menu 
      - Radio type : DIY MEGA2560 radio
   3.2 Build option 
      - ST7920
      - frsky
      - sdcard
      - more option as you want

    3.3 Default Stick Mode(Futaba)
      - Mode3 (AIL ELE THR RUD) 
    3.4 Default Channel Order (Futaba)
      - A E T R
4.Flashing Arduino MEGA2560 by using usbtiny.
    See detail of flasing procedure in Github.

5.Testing hardware post-installation.