Friday, 2 December 2016

How to flash RF firmware on Horus running OpenTx

In this post, I'll describe a simple method for flashing the RF firmware on a Horus transmitter running OpenTx. The SD card is not altered in any way.

Flash FrTx first

The RF firmware is only available as part of the FrTx package. Therefore, in order to flash the latest RF firmware you must temporarily install FrTx. The RF firmware is flashed automatically the next time the transmitter is powered up.

Once the RF firmware has been flashed, you can restore OpenTx.

Here's the procedure in more detail. It's a combination of the methods published by mac44magsindre and Tadango on RC groups. Note that the SD card is not touched in any way.

Make sure you have the following to hand:
  • PC with Zadig driver and OpenTx Companion installed
  • The FrTx operating system firmware. This is provided as a bunch of .bin and .dfu files, you will need the .DFU file. Two .dfu files are provided, one with EU firmware, the other with FCC/World - choose the correct version for your system. [Edit 9 March 2017: the most recent version of FrOS is provided as .bin file only which can't be used with the method described. The last version with a .dfu file is 1.2.24, this is the version I'm using.]
First, back up your OpenTx firmware. From this point forward keep transmitter switched OFF until instructed.
  1. Connect Horus to computer via USB
  2. Start Companion
  3. Backup your OpenTx firmware, by choosing "Read Read firmware to Radio" and saving the file.
Now still with the transmitter switched offflash the FrOS firmware,
  1. Remove the SD card
  2. Connect Horus to computer via USB
  3. Choose "Write firmware to Radio" in Companion, specifying the FrTx .dfu file. Wait until it completes (it may take a few minutes), then unplug the USB cable. Ignore product ID warning.
Next, flash the IXJT firmware:
  1. Power up the transmitter. The transmitter will display a message "Component IXJT updating". 
  2. After flashing, the transmitter will shut down on its own - do not switch on yet. 
Finally re-flash OpenTx:
  1. With the transmitter still switched off, re-insert the SD card, and plug in USB cable. 
  2. Choose "Write firmware to Radio" in Companion specifying the OpenTx .bin file which you saved earlier. It'll take a few minutes to flash.
  3. Switch on the transmitter, and you should be back in OpenTx.
You should now be where you were before you started, but with the latest RF firmware installed. Depending on the firmware version, you may find that you need to rebind your receivers.

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