That's right, Nintendo's Motion Plus addon is out, and inside is a 3 axis, 16 bit gryo (well, a 2 axis gyro and a 1 axis gyro). Which is way better than the 2 axis, 10 bit one I was expecting. Communicates via I2C and costs less than $20. This could be pretty revolutionary for hobby IMUs. Coupled with a Nunchuck, its a 6DOF all digital sensor for $40!Details on the innards and protocol here.For the moment, it seems that you need to switch between the Motion Plus and the Nunchuck via a somewhat complicated method. Can't just read them both from different addresses. Hopefully that will be resolved when people better understand what's going on inside it.There's also some mention of it being able to run at two different sensitives toggled by some i2c command. And possible temperature compensation (they did this in software, only using the gyros?)Eventually I'll write some arduino code for the Motion Plus, but there are probably lots of you out there who could do it better/faster, so by all means give it a go!PS: Anyone know about progress on adapting the DCM method to ardupilot/arduino?
Alternatively, wiimote + motion plus gives you a wireless (bluetooth) 6DOF IMU with a built in infrared cam. Not what I need, but surely useful for someone.
Roy, while the wiimote has an accel in it, you'll want the nunchuck (also has an accel) if you are looking for an easy wired i2c connection. Other than that, correct. I see the protocol called "400kHz fast I2C"...not sure what that means about actual data rates...
Hah! I suppose that works too. But dealextreme.com sells a tri-prong screwdriver for $0.85 (fee shipping!), so I'll be a little patient and make sure nothing inside gets damaged.
I'd be very grateful for any info you could give on the I2C communication once you've got it all sorted out.
I had the motion plus apart the day I bought it on June 6 from Best Buy. You are right, coupled with a nunchuck for $15 you have an i2c 6DOF unit for $35. Amazing !!! AND, great resolution. BTW, the resolution can be changed via i2c as well as reading the x,y,z gyro and x,y,z accelerometer. I am still decoding stuff...I'll post when I get further along.
Earl
@Todd: Pretty sure all of that is I2C. The addresses discussed there resemble the method I've seen elsewhere for communicating with a nunchuck via I2C. Uh...I think. Could be mistaken
@Jack: Why in the world would you want to do that? You've got a board designed specifically to give you a high resolution digital 3 axis gyro. Maybe you could bring down the weight a bit by salvaging the gyros, but doesnt really seem worth it to me.
I believe the documentation / protocol you point to is over the wireless bluetooth (I don't see anything related to I2C adresses / registers and motionplus), has there been anything done towards listening on the I2C, and getting the data straight through hard connection?
Comments
I'd be very grateful for any info you could give on the I2C communication once you've got it all sorted out.
Earl
@Jack: Why in the world would you want to do that? You've got a board designed specifically to give you a high resolution digital 3 axis gyro. Maybe you could bring down the weight a bit by salvaging the gyros, but doesnt really seem worth it to me.
-Todd
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