Tuesday, June 3, 2008


For the past months I have been teaching myself microcontrollers, just for kicks, and my first real project was hooking up two accelerometers<->microcontroller<->PC through USB and see what kind of games I could do with that. I completed the hardware, but had little time to do any fun games. Probably in the summer.

In related news, my mother is a teacher at a local school and one of her students cannot use the mouse, he has a motor problem that I do not know the name – when he tries to hold something steadily, his hands start shaking and he loses all precision in his movements. Well, my mother had seen my 'accelerometers' working, so she asked me if I could do a special mouse for the kid that didn't require steady control. Well, I've read that there are more appropriate methods for cases like this, such as eye control, but they are expensive and you cannot carry it around from computer to computer. Plus, since my mother was paying the bill, it seemed like a good idea to do something like this from an educational point of view :D .

After I did the setup I described in the first paragraph, I had been reading about some nifty experiments with the nunchuck controller. For 20€ you get an accelerometer, 2 buttons and a joystick – a lot of bang-for-the-buck. Plus it would give a pretty sexy mouse. So when I started thinking about the project, it was quite an easy choice of nunchuck vs discrete accelerometers (this and this for example, if you know any cheap dealers in europe, please tell me). Plus I had found some nice information on the internet, and it seemed it wouldn't be that hard to wire up.

In the next pages I am going to report what I did and how I did, just so that anyone which is seeking information as I did can use it as reference. I will talk about:

  • Where did I learn what I needed to know
  • How I wired the hardware
  • How I made it a HID mouse that works in any computer (used example code from Microchip's PICDEM USB demo board :D)
  • How am I processing the joystick and acceleration data to generate mouse movement
  • Discuss that accelerometers working as inclinometers really suck compared to normal mice.

I would like to meet the kid and make a video of him using the mouse, but I'm currently busy (exams) and don't have much time. If anyone has knowledge/experience about what works better in a situation like his, I would be very very interested to know, please post a comment and I will be extremely grateful.

The Nunchuck Mouse with its guts open.

I am currently building this blog so there are quite a few pages missing. I will probably complete it till Sunday.

1 comment:

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