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Firmware source code for RfDesign 900x series

Hi Guys,

Could somebody point me where I can find the source code for the RfDesign x series radios? They contains a new ARM based EZR32 wireless uController and RfDesign states that the firmware is ported from SiK, therefore it must be open source as well. I’m planning to add some features (SBUS, Auxiliary data channels) but was not able to find the source code…

Thanks is advance!

Their official fork is here:

No it is not there, that is a very old version, contains source code up to version 1.9 the 900x uses version 2.6 and a completely different processor (ARM-M3 EFM32 from Silabs).

If you buy one, and it has FW derived from SiK … then they (RfDesign) are forced to give you the source code, if you ask them to.

Bought and asked, no reply so far.

I guess they are not forced to do anything: BSD 2-clause

The 900x (868x) and their TXMODs look like a very promising approach to eliminate all these closed source black boxes related with RC radio links. Unfortunately, the situations seems to be not much better here. Too bad…

Today I found The TXMOD has proper sbus which is good as I tested it.
Since I got the TXMOD in last June, I tested it with 3.07 version.
PPM was good but Sbus was bad. Moreover, TXMOD firmware which is listed in support page had bugs which result in malfunction.
I requested it fixed with hardware change. And today, they completed to upgrade it with version 3.09 for x900x and I got the New TXMOD already.
The result of test was good.

Now I can control the UAV with sbus, though it is 20km apart from Taranis x9D RC Transmitter.

By the way, is there any difference between RC-override through mavlink and sbus control in the perspective of delay?

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do you know if they have any release notes on this firmware, I have been waiting for sbus passthrough for quite sometime, ever since I saw they added it to the tools just waiting on the firmware!!! Coool
do you have the pinout for s. bus passthrough, do you know which pin on the txmod it is?

Looks like they updated user manual for the 900x which has instructions on how to enable sbus on firmware 3.09 looks like it is using same pin (15) as the ppm passthrough. Also apparently you can feed the tx ppm and set the rx to spit out sbus.

Is it the V1.1 manual or have you found another?


Thank you very much, that’s a different v1.1 I could download from their website.


The firmware for the 900x series radios isn’t released as open source unfortunately.

We found that our products were cloned quite quickly for the RFD900+ and 900u series modems and made the decision to not open the 900x and later modems.

If there are any new features required, or something that would be really cool, we would most definitely welcome feedback, comments and requests!. We have worked with some OEMs on collaborative feature development, so, anything is also possible :slight_smile:

SBUS has been recently added, and have put a lot of work into the multipoint firmware on the 900x and 900ux series modems, with around 30 modems synchronised in a network concurrently.

Seppo @RFDesign

I have upgraded to the newest 3.09, and am having trouble getting sbus to work properly. I am using rfd tools 2.33 and tried entering the sbus passthrough in command line and in the gui and it seems like it doesn’t stick. I am also curious about how the sbus and ppm passthrough work together as the manual is a bit vague on that. I there any work being done on the 900u to support ppm or sbus passthrough?

Very nice, just one question, when will the ux series available in 868Mhz version ? Here in Europe the 900Mhz version has no use… :smiley:

Hello, Yes, there will also be an RFD868ux … Pilot runs are being assembled at the factory at the moment!. Planning to have 900ux and 868ux available for purchase in about 3-4 weeks.

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When you say 900ux, does this mean these smaller 900ux will be able to communicate with the bigger 900x modems, is that the only difference between the 900u and to 900ux?

The product description on the RFDesign website says the ux model is “Fully compatible with RFD900x modems.” So it looks like they should be able to communicate.

Shoot I didn’t see that they had updated the page! Thanks for the info!

hi everybody. I have a very basic question about those modules, which i could not find answer reading the manual (TXMOD+RFD868ux, peer-to-peer).

How the binding works? I hope there’s a quick and convenient “push one button on each side” a-la frsky, something which don’t require to connect module with a PC. I couldn’t find such a procedure in the manual, though. I see the TXMOD has a button, is it for that?

Otherwise, i used old sik radios like 3DR and they don’t have any pairing procedure, just a silly and useless “net ID” selection which is weak from a security perspective and unconvenient since you need to connect module with a laptop running mission planner, etc…

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