Spektrum Dx6i interception/injection Board

some time ago I broke my DX6I 2.4ghz transmiter, not the full radio, just the transmiter board... The Power Amplifer went away due to the break of the antenna...
I'm still waiting for another transmitter board, but already made a modification based on the transmitter of a hobbyking radio that accept PPM In as signal to continue flying.
As I was browsing web trying to find a explanation of the serial protocol used by the DX6I motherboard (DX5e has a spi protocol so the transmitter is not compatible), I found this Website : Dx6i Channel expander .
Thanks to him (and the google translator) I figured how was the motherboard acting, and decided to make my own interface with much more functionnality.

The basics features :
* Grab DX6i motherboard serial line and decode it
* Translate the 6 channel into a negative PPM signal

The advanced fetaures :
* Send decoded channel over USB (if connected)
* Send decoded channel over Bluetooth (if connected and usb disconnected), ok I'm not sure that adding Bluetooth inside a 2.4Ghz radio is the idea of the year, but it is funny.
* inject/modify channel from Bluetooth or usb
* Expand Channel Number of the radio
* Grab PPM In and translate it to channel (still lot of work to do here...)

The more advanced fetaures :
* Send all channel in parallel to a rf22 433Mhz transceiver to add Long Range Failsafe (on the receive side a rf22 and a µc is acting like a satellite) (the 433Mhz is the same used on the [OpenLRS|blog.flytron.com/category/openlrs-project|en] project)
* Receive 433Mhz telemetry from the rf22 and send it back to bluetooth/usb
* The board is aslo designed to act as a receiver (lot of correction to do here)

At this time, I made a proto board that seems to work, the USB is not working the way I would like it for now, but on the good way.
I would like to have a composite usb (CDC RS232 + HID joystick), but for now only the CDC is working, the HID don't want to start...
The Bluetooth is working, I can connect it to my smartphone and receive the channels informations :

dx6i interception/injection board from BARTHELEMY Roman on Vimeo.

The PPM out is working nice as the servo out (x8)


The RF22 seems to init smoothly, I have to build another board to make them talk each other.

I'll soon be able to play to my PSX emulator using my DX6i ;)
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  • Have you been able to test your board for more than the 6 channels?

  • Ok, well good luck with your project and keep us updated.
  • hello,

    yes it is possible to send data to the transmitter (rc channels).

    No I'm a little stuck, I can't get a transceiver (the small module that is in the transmitter) replacement, so I had to use a trick to make it work...

  • I'm sorry i'm having a hard time understanding, so there is a possibility for sending data from the phone to the transmitter (phone->transmitter) or is it data telemetry?
  • hello,

    In one way (Radio->phone) I send the servo positions given from the radio and the telemetry data that cames from the 433Mhz transmiter, and on the other way, I can send new data instead of the original ones and eventually add channels.


  • Can you explain a little deeper on what you were able to do with the Bluetooth because I'm very interested in controlling things from my phone.

  • if cheaper is not buying a 10ch Spektrum radio, Yes it is cheaper ;)

    but you still need something to inject your channel, for me it is my smartphone who's doing the job over bluetooth, and I plan on using the inside Accelerometer/Magnetometer as channels for FPV flying ;)


  • I'm working on somthing similar. An dedicated FPV video rx and camera movement (HEAD TRACKING) tramsmitter.Actually I grab the PPM signal from a head-tracker gyro (the one from HK) with an Arduino. I process that signal to a 2nd Arduino (the first one operates with an interrupt an cannot do much more than decode ppm) that re-encodes ti to a 8ch corona DIY tx. So I expand from 2 to 8 channels

    Thath 2nd board has some control sticks for the manual movement of the cameras and some switches to trigger the video switch on board and operate the zoom of the 2nd camera (I will use a fpy camera in the front and a 30x optical zoom camera in a dome on the plane belly). The idea is to completely indipendent system leaving the "normal" rc tx/rx free from any fpv operation.   

    I can say that synchronize all that ppm signals was not easy. But i'm at a good point. Maybe i'll post that project later.

  • NIce, so we could go up to 10 maybe. That would be great. Spektrum is releasing a 10 channel DX system in June

    See here:


    So a 10 channel receiver will be available, maybe we can make it work with this! For cheaper


    DX10t 10-Channel Transmitter/Receiver OnlyMode 1-4 (SPM2800US): Spektrum - The Leader in Spread Spe…
  • I think you can add 2-4 channel more to the original 6ch transmitter, but you have to have the good receiver.

    I believe the maximum that Spektrum have is 9ch receiver...

    the channel expander has not been tested yet, because I only have 6ch receiver... ;)

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