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node.js for Linux joysticks



[Tim Caswell] has been using gamepads and joysticks to demonstrate his node.js hacks for a long time. The thing is, he has been relying on C++ bindings to handle the hardware while trying to herald the praises of node.js. Why not cut out the middle man and write a joystick driver in node.js? It turns out to be so simple anyone can do it.

Granted, this is not a kernel driver. He’s relying on the Linux kernel to recognize the hardware and provide him with the customary /dev/js0 file which he can then work with. As you can see in the snippet above, he’s looping through code in order to constantly read from the hardware. To get this far he dug through the documentation for joystick packets (yay for open source!) to find that each is made of a 32-bit timestamp, a 16-bit value, and two 8-bit numbers identifying the event type and button or axis.

Once he has the packets, it’s off to the races. Each data type is parsed into an appropriate variable which you can use in the logic of your own program. Don’t be nervous, this will make a great weekend project!

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Via Hack a Day, Published: 2012.08.04


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http://hackaday.com/2012/08/04/node-js-for-linux-joysticks/