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.

How to Build 8 Channel Transmitter nrf24l01 Arduino

 

       The instruction "How to build 8 Channel Transmitter nrf24l01 Arduino" introduce how to make 8 channel transmitter from 4 channel RC plane.All existing electronic boards had been taken off ,remaining 4 potentiometers of each control channels would be used after and adding new 4 potentiometers for more 4 control channels.
        The rebuilt transmitter would be operated by Arduino controller.The new design program should be applied to remote control various devices via nrf24l01 radio module such as robotic arm,multi servoes,rc planes,rc tanks,rc cars,rc boats ,etc.
        See the application for 8 Channel Transmitter in "How to Build Gripper Tracked Robot Via Nrf24l01 Arduino"

       

Materials & Tools
1. 1 - Arduino controller - Nano

2. 1 - NRF24L01+PA module with SMA anttenna


3. 1 - Socket adapter for NRF24L01(For protect & stabilize NRF24L01 module)

4. 2 - LED 4 mm.(green and red)

5. 2 - Resistor 1 kOhm. 1/4 watt.(Option)


6. 1 - Capacitor 0.1 microF /50V.


7. 1 - Capacitor 1 microF /50V.
8. 1 - Capacitor 100 microF /50V.
9. 1 - Diode 1N4001
10. 1 - 7805 IC Regulator 5V.
11. Dupont wires

12. Female pin header

13. Dupont Jumper Cable Housing Male Pin Connector


14. Dupont Jumper Cable Housing Female Pin Connector

15. Male JST Battery Pigtail

16. Heat shrink tube 1.5 - 10 mm.

17. Velcro tape

18. 1 - PCB.DIY. circuit board

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

20. 4-Channel RC Transmitter

21. 4 - B10K potentiometers

22. Electrical 26 AWG wires

 

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 

Body Modification , Electronic Parts Installation & DIY PCB

Body modification & DIY PCB

1. Open transmitter body up,remove old existing PCB ,leave 4 potentiometers Aileron,Elevator,Throttle,Rudder.

  

2. Make DIY PCB according to circuit diagram.(See pin connection below)
*Soldering all devices carefully ,use enough large wire.Making good ground.
3. Drill transmitter body for installing 4 more potentiometers.
4. Cut off plastic body to open a hole for Nano USB.
5. Paste Velcro tape at the transmitter back for battery attachment.
6. Install DIY PCB and NRF24L01 module on transmitter body by hot glue.
7. Connection wiring between DIY PCB , Potentiometers , main switch and battery terminal.

8. Assemble transmitter body back.
*Before connecting battery,check out to find short circuit points on DIY PCB.Otherwise it can smoke and burn everything. (Be careful of Lipo battery , it's high current supply , short contact will spark fire)

Arduino Nano Connection pin No :
A0 - Auxillary4 potentiometer
A1 - Aileron potentiometer
A2 - Elevator potentiometer
A3 - Throttle potentiometer
A4 - Rudder potentiometer
A5 - Auxillary1 potentiometer
A6 - Auxillary2 potentiometer
A7 - Auxillary3 potentiometer
D3 - Throttle hold LED
D7 - Throttle hold switch
nRF24L01 module Socket adaptor to Arduino Nano pin No :
Vcc - 5 V. supply (Do not connect 5V. direct to nRF24L01 module,it's supplied only 3.3V.)
GND - GND
CE - 9
CSN - D10
SCK - D13
MO - D11
MI - D12
IRQ - D2
*If you have communication problem,you can change connection from pin 13,11,12 to pin SCK,MOSI,MISO of Nano programming pins.
*It's necessary to add 0.1 microF to nRF24L01 module pin Vcc/GND because the module needs stable current and voltage. Also solder a small wire at the antenna to increase control range.

Software Installation
1.Down load nRF24L01 module library zip file from https://github.com/maniacbug/RF24/downloads.
2.Add library zip file to Arduino IDE.(After finish addition, you will see new library RF24-master in Examples menu.)
3.Before using new nRF24L01 modules,we shall burn the modules by uploading default sketch pingpair and GettingStarted for tuning up frequency otherwise it will has uncommunication problem. (Use another Arduino Nano/UNO and nRF24L01 modules for pairing)

4.After matching the frequency ,we can upload Tx code sketch from GitHub to rebuilt transmitter.