I am trying to get an old RCX working with leJOS. I already have it working with NQC and BricxCC.

While NCQ/BricxCC seems to recognize my usb-to-serial (which appears as "COM5" to the OS), the leJOS I downloaded does not. I believe that it uses Java rxtx on Windows to access the serial port.

There seems to be a number of pieces I will need to get into place to make it work.

I am running Windows 7 professional Version 6.1 (Build 7601:Service Pack 1) on my work laptop (I have OS X on the desktop at home - I suppose I could boot to Linux from a USB or CD on my work machine if I really needed to.)

If I stick with Windows 7 I will need a version of the RXTX DLL which works with:

  1. this version of Windows
  2. my COM5 port (which is really usb-to-serial).

I also need a version of Java which works with the leJOS java source code, (found some references that not all JVM versions work) and that version of RXTX/DLL and the RCX (not the NXT...I don't own one).

Alternatively I figure I can upload the leJOS firmware with NQC, but after an hour of trying different searches on the internet I can not find the location/name of the firmware file, or build instructions.

The leJOS forum looks like no-one has posted to the RCX section since 2014, so I thought I might try here.

I'd prefer a Windows 7 solution (as that is where BricxCC and NCQ live now), but I would be willing to consider alternatives if no Windows 7 solution exists.

  • I can't really help, since you've done everything I would have done. The RXTX Java stuff is famous for being very version sensitive across deployments. My only advice is, assuming the DLL you have works for Windows 7, make sure you pass the full, quoted path of the RXTX DLL to Java via "-Djava.library.path". Also: architecture counts! If you are using the 32-bit VM on 64-bit WIndows, you need to be 32-clean with all libs.
    – user3971
    Commented Apr 28, 2015 at 19:08
  • To follow-up on my comment, the "official" RXTX 2.1.7 Windows binary package seems to be 32-bit only. So, if you are using that, make sure you are using a 32-bit Java runtimes when running stuff that needs gnu.io.*
    – user3971
    Commented Apr 28, 2015 at 19:35


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