Patching the LEGO Mindstorms NXT Bluetooth Mobile Application

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Last month I wrote an entry about the LEGO Mindstorms NXT Mobile Application that allows a great deal of control over your NXT kit via Bluetooth. It’s a really great little application. I actually demonstrated it briefly at the local Make:Philly meeting last night as follow up to a previous presentation I had given on robotics, Flash and Legos. Well, there is one totally annoying aspect of the application that tarnishes an otherwise perfect implementation, which I noted in my previous entry. Whenever you launch the application, it has an animated intro screen that plays a really annoying 13 second long bit of techno-like audio. It wouldn’t be that bad, but there is no way to skip it, or disable it, and its really loud. You have to endure it every time you launch the application. Totally annoying and poor usability. I never had any luck contacting the developers at Nearcell, who made the app for LEGO, and their website is not much help either. So, I decided I had to patch this on my own. Here is how I was able to patch the application so that you can shorten/change the intro or replace it entirely with one of your own liking.

  1. Grab the application from the Lego Mindstorms NXT site
  2. Unzip the resulting download.
  3. Navigate to your phone model folder – in my case the Nokia 6680 folder and locate the .jar file for installing the application on your device. (I’m using it on a Nokia N70 without issues, so it should work on other Series 60 devices – your mileage may vary)
  4. Create a very short MIDI (.midi) file here with an excellent online .midi file creator. The idea is that we want a very short quiet file. For comical demonstration effect on the effectiveness of this patch, I’ve decided to use the more apropos song Mr. Roboto by Styx
  5. Rename your new or favorite .midi file to “jb.mid” and place it in the same folder as the NXTmobile.jar file.
  6. Bring up a terminal session in OS X, or a command shell on Windows (Windows folks, you’ll need some JAVA tools installed, specifically jar command line application – Mac OS X users you’ve already got it)
  7. Issue this command from the terminal prompt: jar uf NXTmobile.jar jb.mid
  8. What that has done is replaced the annoying, far-too-long intro sound in the .jar, with your own new .mid file.
  9. Transfer the new .jar file to your device and install it, run the application, and enjoy the shorter startup time!

The intro animation will only play as long as the .midi files duration, so if you want it short, keep your replacement .midi file short. Here is a quick video I made through Viddler.com that demonstrates the new startup and sound.

if you were so inclined, you can also use the same method outlined above to replace the .png files in the intro animation or elsewhere within the applications UI. Also, if you have some file manipulation utilities installed on your device, you could try doing all the replacements right on the device itself, but the method above works well on supported devices. Happy hacking!

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