===== Installing Deviation on the F12e/F7/F4 =====

The Walkera F-series transmitters have a very small Flash space.  Too small for the traditional FAT fielsystem used by Deviation for other Walkera transmitters.  Instead a custom filesystem was designed for these cases called 'DevoFS'  The filesystem installation is different because of this.

After following the typical installation (using the DfuSe tool, or <del>Deviation Uploader</del>//-Note that only a custom build of the deviation-uploader works with the F4/F7, the recommendation is to stick with the Walkera DfuSe tool-// to install the dfu file), rebooting the transmitter should result in a screen that says 'Deviation USB'

At this point, if you plug the transmitter into the PC via USB it should be detected as an external drive with a single file 'devo.fs'  This is a trick used in Deviation to provide a mechanism to directly access the filesystem.  Do not attempt to delete this file or to format the filesystem.  These tasks will not damage your transmitter, but they also will have no affect.

If you have the devo.fs file that came with the firmware (in the zip file), you can copy this to the transmitter now.  This has been found not to work on MacOS (see below for the alternative).

If you need to modify the files on the transmitter (add new models, change the hardware.ini), or if the copy method above doesn't work, you will need the following instructions.

==== Extracting / Creating the devo.fs file ====

First you will need the buildfs program.  If you use Windows, you can download the compiled version here:

[[https://www.deviationtx.com/downloads-new/category/3-miscellaneous?download=5092:buildfs-exe|Download BuildFS]]

Or you can use the python script (you need to have python2.7 installed) here: 

https://raw.githubusercontent.com/DeviationTX/deviation/master/src/target/common/filesystems/devofs/buildfs.py

You can extract the files from devo.fs using:
<code>buildfs.exe --fs <path to devo.fs> --dir <directory to write to> -x</code>

This will create a directory with the contents of the devo.fs.  To reverse the process and create devo.fs, you can use:
<code>buildfs.exe --fs <path to new devo.fs> --dir <directory where devo.fs was previously extracted> -c</code>

Note that the path to devo.fs can be the path to the transmitter itself, and this is the best known way to install devo.fs on a Mac.