As for data. I guess one question I have is: what motion (if any) was occuring while this data was recorded.
The next question is how to interpret your accelerometer values, which are in the range of 475 to 569 or so. How does this relate to millivolts coming out of the accelerometer? Sorry, I havn't played with the controller in a while... and when I did, back in 2002... well... everything was different
Anyways, according to the
Sensor Manual, it would appear that horizontal orientation under no acceleration should be outputting 2.5 volts.
According to the
Data Sheet, it would appear that the 0g corresponds to 1.65V given a 3.3V input. I think first is driving it with a 5V input. So a 0g output of half of Vs seems to be self consistent here.
So the first thing we want to verify: is the meaning of your numbers there somehow consistent with the ~2.5V +/- 1.7V that we expect to see from the output of the device?