DumboRC DDF-350 Transmitter Firmware Modding

ℹ️ Current Supported Firmware Version - 1.1.5 ℹ️

ℹ️ Current Mod Version - 0.7.0 ℹ️

Versions 0.7.x Targeting Long-Term Firmware Release 1.1.5

Version 0.7.0

Improved translations for EN and DE:

• No scrolling.
• Reduced ambiguity.

Transmitter battery display option for four NiMH cells:

• Range: 0% at 4.0 volts to 100% at 5.6 volts.
• Lower possible transmitter voltage alarm setting down to 4.1 volts.

How to Install

⚠️ Important note: The transmitter is very specific about USB cables. Even if a USB cable works as a data cable for a phone, PC, etc., it may not work with the transmitter. ⚠️

Symptoms include "USB device error" or the device's flash drive not appearing. Try different cables, one by one, until one works.

⚠️ Remove batteries from the transmitter before performing upgrades. ⚠️

⚠️ Upgrading from Firmware Versions Lower Than 1.1.5 (Stock or Modded) ⚠️

If your current firmware version is lower than 1.1.5 (stock or modded), you need to first update to the stock version 1.1.5.

The process depends on your current version. Please refer to the official video and website for detailed instructions:

Official DumboRC site with firmware for DDF-350

Once successfully updated to 1.1.5, return here. You will not need to go through the entire boot update process again.

Upgrading 1.1.5 Stock <-> Mod or Upgrading Mod Versions

⚠️ Important note: Always start patching with a clean original 1.1.5 firmware file, DDF.bin. Do not reuse files altered by previous mod releases. ⚠️

1. Start with the 1.1.5 firmware file, DDF.bin:
   • You should already have this file from the initial upgrade to stock 1.1.5.
   • ⚠️ Always apply the patch to a clean original binary. ⚠️
     • Applying the patch to a previously patched binary will result in glitches.
   • This mod works ONLY with the 1.1.5 download.
2. Back up the official 1.1.5 files:
   • DumboRC removes previous firmware versions from their website. If you ever want to revert to a specific version, or if I lag behind on supporting new versions, your only reliable source of original files is your backup.
3. Download the tool LunarIPS here:
   • I cannot distribute the official firmware but can distribute my ROM hacks.
4. Download the latest .ips file:
   • Visit the latest release.
   • Under "Assets," find and download the .ips file.
5. Use LunarIPS to apply my "Romhack" to the clean original 1.1.5 binary file:
   • LunarIPS modifies the binary file "in place." Ensure your backup remains intact.
   • Make sure you are applying it to the .bin file, not the .zip.
   • Ensure you are applying it to the firmware file, not any of the boot files.
   • If you cannot see the .bin file in LunarIPS, change the filter to all files / *.*.
6. Flash the modified binary file as described in the official instructions. For convenience:
   • ⚠️ Remove the batteries from your transmitter. ⚠️
   • Connect the transmitter to a computer using a USB cable with data capabilities:
     • ⚠️ The transmitter is very specific; not all cables will work. Try several until one does.
   • Press and hold the CH3 and CH4 buttons, then turn on the transmitter using the power button.
   • The screen will flash "black," and you will hear a chime. Release the buttons.
   • On your computer, a new USB flash drive will appear.
   • Run the official .bat file to flash the image:
     • Manual copying does not work because Windows creates "System Volume Information," disrupting the process. The official script handles this.
   • After the .bat file completes, "Safely Eject" the flash drive.
   • Unplug the transmitter.
   • Reconnect the transmitter or insert the batteries.
   • Turn the transmitter on. The new firmware will flash automatically, and you should see the changes.
7. Enjoy! Drop a star on this repo or "watch" it for updates. These numbers mean a lot to me and let me know that my work is appreciated by the community.
8. If you found this useful, consider supporting via Ko-Fi or GitHub Sponsorship (one-time or monthly).

Known Limitations

1. Four NiMH 0% threshold of 4.0V is not ideal:
   • It aligns with four AA cells and the lowest alarm voltage.
   • The transmitter likely will not function below 4.0 volts.
   • The lowest voltage setting appears to be 4.1 volts, controlled by the bootloader. I will not modify the bootloader (the part that initializes the transmitter).

Safety, Warranty, and Responsibility

I provide no guarantees of safety and am not responsible for any damage.

I test everything on my own transmitter, so I have "skin in the game." However, I cannot predict every situation.

Avoid performing upgrades the day before important events.

Development Details

Translations

With the help of ChatGPT, I developed Python scripts to dump and insert UTF-8 strings. While some strings are too short, unrecognized, or have incorrect offsets, the process is relatively smooth.

I recommend creating or modifying a "translation" file instead of editing raw binaries directly. Tracking changes in raw binaries can quickly become chaotic.

The current EN translation is 98% satisfactory. The DE translation removes scrolling; suggestions are welcome. I presume the CN translation is good. If you'd like to improve FR, create an issue, and we’ll collaborate.

Logic

Starting with version 1.1.3, I began publishing my Ghidra projects publicly. These allow you to follow my changes or make your own collaboratively.

It is still not Git-based, since Git replaces common server storage. As such, if you want to do something, let me know in the issues, I will make sure to upload my latest changes and take a break to allow your changes to pass.

You will need Ghidra. I use Ghidra 11.2 Public

You will need to set up ./ghidra_repositories folder of this repo as ghidra.repositories.dir in server/server.conf.

You will need to disable authentication in server/server.conf.

• Find wrapper.app.parameter.1=-a0, comment the line with #, change .2 to .1 on next parameter.

• For me it now looks like

  #wrapper.app.parameter.1=-a0
  wrapper.app.parameter.1=${ghidra.repositories.dir}

You can set up user name as user.name / VMARGS=-Duser.name= in support/launch.properties. Or by default your username is OS user name.

Add your username to ghidra_repositories/users of this repo, like YourName:*:*. I will be honored to not be alone there.

I run server in console mode, since I do not intend to use it as actual network server.

Once server is running, start Ghidra tool itself.

Click "File", "New project", "Shared Project", Server Name "127.0.0.1" (I presume you run server locally in console), "Existing Repository", "ddf-350-113".

Select folder to store files locally.

To start editing, RMB .bin file and do "Check Out".

After you did some changes and want to make a save, do "Check In...".

Once you are done want want to share changes back, do "Undo Checkout". Then close Ghidra, then stop Ghidra server with Ctrl-C.

After that commit all files in git, push.

To test the changes, export .bin file as "Raw Binary" to translation folder. If you want translations, use input.bin, otherwise just use DDF.bin.

To add translations to input.bin run import_strings.py.

Run update.bat that is just verbose translated official update script. Process is as usual.

If you flashed garbage, just flash working version again.

Feedback and Suggestions

If you find translation issues or better wording choices, let me know. My primary goal was to eliminate scrolling, which caused me eye fatigue and headaches, and to update outdated terms.

For feedback, create an issue and include a picture and your suggested text.

Legal Disclaimer

I am not associated with or endorsed by DUMBORC, RadioLink, or any related companies.

All firmware and hardware are their property. I only distribute my modifications, as permitted under the concept of derivative works.