Perl script controls toy USB canon
Replacing Tin Soldiers
© Jan-Paul Herr, pixelio.de
Although a USB toy such as a polystyrene rocket launcher only includes a Windows CD, it works fine on Linux with a spot of reverse engineering. With libusb, this doesn't even require compiling a device driver – Perl controls the device from userspace.
Trouble at the office? It doesn't necessarily need to lead to a battle, such as in the video The Great Office War [2] by toy manufacturer Hasbro. Even if you don't have an attack plan, the USB-controlled Rocket Baby rocket launcher (Figure 1), by Chinese manufacturer Cheeky Dream, is a bargain at less than US$ 20. Not only did it cheer up my colleagues at work, it also gave me an opportunity to study the Linux kernel's fairly complex USB subsystem [3].
Opening the box reveals a CD for Windows XP, but no trace of a Linux driver. This seems to have provoked a number of gadget fans in the developer community to investigate the USB protocol the toy uses on Windows with USB sniffers such as USBsniff, to reverse engineer the interfaces, and create bindings for languages such as Python, or even for completely different operating systems [4].
When the toy is plugged into an empty USB slot, the Ubuntu Hardy Heron distribution autodetects it. The kernel messages, which can be read in the /var/log/messages logfile (Figure 2), tell you that the toy rocket launcher is now connected to the Intel-based PC's UHCI controller.
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