Many of you might know the Sky9x upgrade board for 9x-model Chinese radios. It boasts an ARM Cortex M3 32bit processor and a whole bunch of additional features, such as audio out, SD card for saving configs, USB programming interface and so on. It runs on the very feature-rich and mature open source firmware Open9X. It has a PPM out, so with the right connector board, it can run with any TX module, may it be Futaba, JR, FrSky, Orange, Lemon, whatever...

The official feature list:

-  Atmel SAM3S Arm Cortex M3 32 bit Microprocessor (256K EPROM , 48K RAM , 64Mhz)
 - Built-in USB port for loading new firmware , and to access the SD card as a Mass storage device.
 - Connector for LED Backlight , with software dimming control
-  1/2 Watt  audio amplifier with 8 Ohm Speaker Output  and support for a headphone jack
-  4Mb EEPROM provides on board storage for 20 - 40 models depends on software used.
- Support for Koycera  64x128 LED backlight LCD  
- Two , internal RS232 Serial communication ports  with support for external 2.5mm jacks..
- FrSky Telemetry can hook directly up to board (no convertors needed)
- Micro SD Card Socket for Sound , Model and Telemetry logging / storage.
- One , TTL Serial Port , for hookup to a Bluetooth Module , Like RN-42
- Hardware PPM , PXX output   .
​- Haptic Output connector
- AVR Co-Processor , ATtiny167 AVR  , provides 12 more I/O channels and  provides  RTC
  (Real Time Clock) functions , with on board 3V Lithium Battery
- On Board CR2032 Lithium Battery Holder  
- On Board Current Sensor monitors the current being drawn from the battery, and stores
  the amount of mAH used up.
- 5V Linear Pre - Regulator  supplies the Main LDO 3.3V Linear Regulator. For better heat management, and a 5V Switching Regulator Upgrade is available for using  3S Lipo batteries

In my opinion, this board is great! It's way too good to be seen just as an upgrade for the 9x transmitters. It also makes a very nice base for every DIY-transmitter project - that's why I selected it as the RC core for my intergrated groundstation project.

Now, unfortunately, the board is in danger of dying out! Brent, the designer and the guy who makes those great boards as a hobby, wrote in the 9x-forums that problems in the last production run left him 25 boards short, leading to a loss of ~$2500. A pretty big sum for a hobby project!

If you have a 9x transmitter and are looking for more features, if you always wanted to build your own TX or if you are planning to build a version of my UAV Control Station, once my software is getting mature, have a look at the Sky9X-board! Brent wrote that if he gets enough people to pre-order for another production run, the board will continue to live. Otherwise, it will die...

Check the website here:

Views: 7285

Comment by Tilman Baumann on February 7, 2013 at 9:00am

Hm, that explained why I have not heard back from him. Well, I hope he gets those problems sorted out, I would still love to get one.

PS: I wonder, would it fit in the new TX9R? Not sure I'm such a fan of the new model, but I have not made my mind up about that yet.

PPS: Maybe the TX9 graze is over when FrSky comes with their own TX on the market. They announced a TX that will be Opensource, FreeRTOS based and also run a ARM cpu...

Comment by Stefan Gofferje on February 7, 2013 at 9:06am

Nope doesn't fit the 9XR. And from what I have read, the 9XR isn't that great...

Yeah, let's see, what the FrSKY thingy looks like. But there's still a whole lot of 9X out there and the 9X is dirt-cheap.

Plus the Sky9X-board really makes a great base for a DIY-TX or a DIY integrated ground control station.

Comment by Bill Bonney on February 7, 2013 at 9:11am
I'm not surprised that the interest is low as the FrSky product has potential to fix both issues of poor software and low quality components for gimbals etc...
Also see the comment about the gruvin9x
Comment by Stefan Gofferje on February 7, 2013 at 9:33am

From a modding point of view that may be right, although the FrSky TX still has to prove itself. Not every product that was hyped later lived up to the expectations.

But - as I said - I'm more thinking DIY than modding. From the chatter here on DIYD and the resonance to my ground station project, I conclude that many people would like to have a "real" integrated ground station, you know, Peli case and stuff... And buying a great board for CD$85 hurts much less than buying a TX for $250 and ripping it apart :). Plus if you just buy the board, you are free to choose the peripherals like the sticks, for instance.

Comment by Tilman Baumann on February 7, 2013 at 9:41am

True. Tx9 and it's ecosystem might be a bit anachronistic at times and the hardware quality really sucks (Pots picking up all sorts of RF for example). But if it has done anything, it has proven to be extremely hackable.

And it's so cheap and ubiquitous (though sometimes difficult to source)

I still rather have that. Especially since FrSky will most likely not leave a abundance of IO pins available for free use as Sky9x has. Hackability of the FrSky thing has still to be proven.

Comment by Aleksandr on February 7, 2013 at 10:49am

And how to buy?

Comment by baptiste.vial on February 7, 2013 at 11:23am

I have an ersky9x revb and it's a really great board, audio features are really cool when piloting arducopter, you can program a lot of text2speech alerts to perfectly know the state of your aircraft

Comment by Chris Eddy on February 7, 2013 at 11:42am

I'd been waiting for the spring to work on my 9x, but I'd happily pre-pay to keep this project alive.  Awesome work Brent!  Let us know how we can help keep the Sky9x board alive....

Comment by Stefan Gofferje on February 7, 2013 at 2:06pm

Aleksandr: Go to the website ( and send Brent a message if you are interested in buying a board!

Comment by Bill Bonney on February 7, 2013 at 3:09pm
@Stefan: could you not use ArduPPM on a 32u to do the same. This seems like overkill to use this... An Arduino pro could do it. Or is the display driver you are working on?


You need to be a member of DIY Drones to add comments!

Join DIY Drones

© 2019   Created by Chris Anderson.   Powered by

Badges  |  Report an Issue  |  Terms of Service