FrSky X8R & X4R Firmware Update Hack


We are using the FrSky Taranis Plus and X8R and X4R for our PoC quad projects.

We received batches of these receivers from China which had incorrect firmware installed (non-UE) and therefore we needed to upgrade the firmware to enable these to bind to our transmitter.

This took a lot more time and effort than we thought, as there are a lot of methods and details on the web which we needed to filter through and explore before it actually worked.

We created this webpage to share our experiences (and to remind us how we did it) on what we perceived as being the best method to upgrade firmware on a receiver. The best method, in our opinion, is by directly using the Frysky transmitter's in-built serial port to flash the receiver. The advantages being that you don't need to purchase any additional USB FTDI products from Frysky or other electronics or fluffing around with the Zadig USB driver installer, etc.

The biggest confusion when we started was trying to find the "maintenance mode" as the latest Taranis Plus firmware versions (April 2016) is not provided with the "maintenance mode" functionality any longer (i.e activation is by switching-on whilst holding the Yaw & Roll trims pushed OUTwards ).

This maintenance mode allows you to flash any FrSky SmartPort product; such as 8XR, 4XR receivers directly using the serial port connector on the back of the transmitter.

In previous firmware version, this maintenance mode could be triggered by turning on the radio - whilst pushing the right and left bottom trim outwards (not inwards - as this is used for flashing / upgrading the transmitter). It's unclear why this maintenance mode was removed in the first place.

But, a big thanks goes to Mikeb on the opercforum, as he's made available a Taranis transmitter firmware version which includes the maintenance mode functionality again ->here

we take no responsibility for the accuracy of the text or procedures - so follow these steps at your own risk!


Step 1

  • Back up all your transmitter settings (e.g all models) to your SDCard and backup the SDCard to a PC folder. The Taranis firmware back-up is achieved by turning on the Transmiter whilst pressing the left Yaw and Right Roll trims inwards (yes - this time inwards and not outwards). You'll need to restore this file again in step 6

Step 2

  • Follow these instruction from MikeB on the openrcforum to get the FrSky Taranis transmitter flashed with the firmware to enable maintenance mode again.

Step 3

  • Download the latest receiver software from FrySky website e.g for -> X4R. Ensure to identify the correct version for your region and radio (i.e. EU or NonEU).

Step 4

  • Copy these files to the Taranis removable SDcard and ensure to copy these to the files to the correct directories on the SDcard (i.e create a directory call 'Firmware' to differentiate from the 'Firmwares' directory that there already is). We had problems getting a USB connection to the Taranis so we could not upload these directly, so we just took out the SDcard and plugged that directly in the PC and copied the files over on the PC.

Step 5

  • Modify a double ended servo cable (i.e. just switch the power and ground cables on one end of the servo connector) as described on this website - follow the instruction carefully.

Step 6

  • Flash the firmware on your receiver. Here's a picture of the cable connect to the 8XR SPort. (note: don't connect to the sBus).


  • The SPort on the X4R is on the side. Be careful not to get the polarity of the + - wrong, as this will zap the device! The signal wire from the transmitter goes to the Signal pin on the Xr4 SPort. This is the yellow cable in the version I bought - but check first.

  • Follow the instruction on the Taranis screen to flash the receiver. It will find and list all the .bin files you've copied to the Firmware directory.

  • Select the correct version and press ENT. You'll see the progress bar on the Taranis moving and LED's on the receiver flashing.