dji-firmware-tools: unpack, modify and repack DJI drone firmware

What dji-firmware-tools is for, and who it is not for

This repository solves a narrow problem: DJI ships firmware as opaque containers, and the vendor tooling does not let you look inside or change what is inside. The project provides the missing layer. It extracts modules from a package, decrypts signed module files, lets you edit binaries and parameters, and repacks the result into a flashable container.

The README lists the intended uses directly: calibration after repair, parts identification at board and component level, flight parameter modification, firmware modification, and research. The parameter editing case is described as a command line equivalent of DJI Assistant software, useful on platforms that lack the OEM tool or where its advanced functions are locked.

The audience is stated just as plainly. The README says a step-by-step instruction will not be provided, that these tools are for engineers with vast hardware and software knowledge, and that the omission is deliberate, to keep the tools away from people who would use them to disable security mechanisms. That is a design decision, not an oversight, and it changes how you should evaluate the project. If you need a tutorial, this is the wrong download.

How the toolchain works: containers, signatures, then binaries

The pipeline has distinct stages, and the tool names map onto them. A DJI firmware package that begins with the bytes xV4 is handled by dji_xv4_fwcon.py, which extracts its modules or merges modules back into a container. The README gives the Phantom 3 Pro extraction as its example.

Extracted modules are not immediately readable. A module whose .sig file starts with IM*H is encrypted and signed, and dji_imah_fwsig.py decrypts and un-signs it. The same tool can re-sign a module, but only when the private part of the chosen key is available. Keys rotated over time, so when an IM*H file references a key the tool has several versions of, it prints a warning listing the candidates and picks the most recent one for the operation. That behavior is worth knowing before you trust an automatic selection on an old package.

Once a module is decrypted, other tools take over. arm_bin2elf.py converts ARM binaries to ELF using arm_bin2elf_template.elf, amba_sys2elf.py does the same for Ambarella system images with amba_sys2elf_template.elf, and amba_romfs.py and amba_ubifs.sh handle the filesystem layers. The symbols/ directory and the tests/ directory are the practical entry points the README points readers toward when they do not know where to start. The README also states that the source code is intended to act as format documentation, which is an honest way of saying the specification lives in the parsers, not in a separate document.

Installing dji-firmware-tools and running a first extraction

The README does not include an installation section, and there is no package published in it. The tools are Python scripts and C sources in the repository, invoked directly from the checkout, so getting started means cloning the repository and having a Python interpreter available. Nothing in the README describes a pip package, a distro package or a Windows installer.

The first real operation is unpacking a firmware package. The README gives this exact command for a Phantom 3 Pro package:

./dji_xv4_fwcon.py -vv -x -p P3X_FW_V01.08.0080.bin

The -vv flag raises verbosity, -x selects extraction and -p names the package. You should see the tool walk the container and write out its modules. The README notes that this tool is the one to use first when the downloaded file starts with xV4, so check that before anything else.

The second stage decrypts a module pulled from that package. For Mavic Pro camera firmware the README shows:

./dji_imah_fwsig.py -vv -k PRAK-2017-01 -k PUEK-2017-07 -u -i wm220_0101_v02.00.55.69_20161215.pro.fw.sig

Here -k supplies key identifiers, -u means un-sign and -i names the input .sig file. The README gives a second example with the same key flags for Phantom 4 Pro V2 flight controller firmware, and a signing example for Mini 2 that requires a PRAK key with its private part present. If the tool prints a key-selection warning, read it before continuing. The README warns that any warning must be investigated so the final firmware is not damaged.

Signed packages and unknown keys are the hard boundary

The most consequential limitation is cryptographic. The README states that flashing modified firmware may require additional knowledge and software modifications, such as rooting the drone, because some firmware packages are signed using asymmetric cryptography and private keys are rarely available. You can edit a binary; that does not mean the aircraft will accept it.

The key-rotation behavior compounds this. When an IM*H file refers to a key the tool holds several versions of, dji_imah_fwsig.py lists the possibilities and selects the most recent. On an older package that default can be wrong, and the README's own instruction is to investigate warnings rather than proceed. A failed un-sign or a mis-signed module is not a cosmetic error.

There is also a scope limit on communication. The README says the product communication tools currently use serial interface (UART) and I2C, and that you need to connect the drone to a PC for them to be meaningful. That rules out anything wireless, and it means the repository is not a substitute for a phone app. Finally, the README explicitly disclaims a guided path: if you cannot understand how the tools work, you should not use them, and you run them at your own risk.

dji-firmware-tools compared with DJI Assistant and YanDron-style utilities

The natural comparison is DJI Assistant, the vendor application. The README itself frames the parameter tools as a command line version of DJI Assistant, and adds the difference that matters: the command line path works on platforms that lack the OEM software, and it can reach parameters that the OEM software locks behind advanced functions. The trade is real. DJI Assistant validates what you are doing and hides the protocol; these tools expose the packet and expect you to know its shape.

The other class of alternative is the third-party repair utility, the kind of thing people search for as a DJI service tool or a YanDron-style package. Those are typically closed binaries aimed at a repair workflow. dji-firmware-tools is the opposite: GPL-3.0 source, with the README stating that the source doubles as format documentation, and a wiki holding board and component information contributed by enthusiasts and repair technicians. If your goal is to understand a container format or compare binaries across firmware versions, the open source route gives you something a closed utility does not. If your goal is a one-click fix, it gives you considerably less.

Licence, maintenance and the cost of keeping up

The repository is licensed GPL-3.0. If you redistribute a modified version of these tools, or ship a product built on them, the copyleft terms apply to that distribution. That is a statement about the licence text, not legal advice, and anyone embedding these scripts in a commercial repair product should read the licence themselves.

On maintenance, the repository does not publish a last push date, so there is no basis for calling the project actively developed. What can be said is structural: there are no releases retrieved, so consumption happens from the master branch, and the top-level layout shows the project has accumulated tools across several DJI chip families, including Ambarella (amba_*), ARM (arm_bin2elf.py) and DJI flight controller tooling (dji_flyc_*). The supported_firmwares_xv4.csv file is the place to check which packages the xV4 path is known to handle.

Upgrade cost is mostly about firmware generations rather than code. Each new DJI platform can introduce a new container, new keys or a new signing scheme, and the README's key-rotation note shows that this has already happened more than once. Expect to read the Python source when a new package does not parse. That is the maintenance model: the code is the specification.

Editorial conclusion

Adopt dji-firmware-tools if you already read firmware containers and UART traffic for a living, or if you are doing repair calibration and component-level research on DJI hardware. Do not adopt it if you want a guided updater: the README states plainly that no step-by-step instruction will be provided and that the tools are for engineers with vast hardware and software knowledge. Before touching an aircraft, verify that your specific package starts with xV4 so dji_xv4_fwcon.py applies, check the supported_firmwares_xv4.csv entry for your model, and confirm whether the module you intend to repack is signed, because the README notes that some packages are signed with asymmetric cryptography and private keys are rarely available.

Frequently asked questions

Official sources

1. Official README
2. Project repository