Wii Nunchuck I2C question

[AndyHope]

Hey there,

I've been looking into interfacing a wii nunchuck with a 8bit PIC microcontroller
It uses an I2C interface which is fairly easy to use (using some microchip libraries and such) .

my problem is that I bought a knockoff from DX(Deal Extreme, cause it was cheaper) and read online somewhere that it doesn't quite use the same I2C protocol and the real nunchuck.

I find this kindof hard to believe, as it has to be compatible with a wiimote... right?

Has anyone heard about this? ill try using the nintendo protocol and let everyone know if it works

[impossiblescissors]

I can attest that the knockoff nunchucks aren't 100% compatible with the Nintendo ones. I got a nunchuck off eBay that seems to work fine, but it causes Lego Star Wars to hang up at a certain part of the game (during episode II.) I'm also interested in hearing any details about the source of the incompatibility.

[AndyHope]

yeah i've finished interfacing the the wii nunchuck, looks like there are a couple differences in the way some knockoffs are initiated with a startup sequence.

authentic nintendo ones are: (hex values)

0xA4 (i2c address) 0x40 0x00 startup

but my knockoff sequence is:

0xA4 (i2c address) 0xF0 0x55 (startup)
0xA4 (i2c address) 0xFB 0x00 (secondary startup)

it amazes me that the nunchucks are even compatable, this might be why your nunchuck cuts out (possibly reconnecting at that point in the game?).

anyways i realize this is probably a little to indepth but its a good reference ,
plus if your looking for cheap accelerometers the nunchucks are about the best place for them.