Wii nunchuck acceleromter calibration to G force

Hi all,

I have been working on some code for the last couple of days to display the g force from a nunchuck on a nokia lcd. Im newish at this and got this far. Im trying to calibrate the output of the nunchuck into G force. I thought tipping it one way to mark 1 g and the other to mark -1g would be perfect. but doing this i found the outputs straight from the nunchuck when its straight is roughly 135 at 90 degrees one way its 155 and 90 degrees the other way its 60. So it cant be a linear relationship.

Also tipping it oneway slowly the number can get to 110 then suddenly drop to 60. Anyone know the scale it works in and why all of a sudden it can drop large values Hope to hear from someone soon.

So it cant be a linear relationship.

It is. Can you post your code, and a sample of your output? How are you powering the device?

What i am using is the standard wii nunchuck code. I am still communicating to the entire nunchuck over I2C. So im not sure what the numbers represent.
Its a 10 bit resolution number but im not sure how the numbers are calculated
I dont think showing the code is worth it. Its the standard code as shown on todbot.

It just reads in binary values. I guess does anyone know what the nunhcuck does with the data it receives from the accelerometer before it send out the single.

Thanks all

The nunchuck doesn't do anything with the value - you're reading it straight off the accelerometer.

Ohk so there are 8 bytes of data from each direction then the last 2 bits are stored in another byte so you have to put them together so there is a 10bit resolution.

So does anyone have an idea of how to convert these values to g force. I was thinking tipping it on its side and keep it still that would be 1g in that direction and i could calibrate to that.

Any ideas.