I read an article here - How to use the ADXL345 accelerometer sensor it was said:
With the output resolution of ADXL345 being default to 10-bit, we can conclude that the change in acceleration of the object to which the ADXL345 is mounted must be at least 3.822 cm/s2 for +/- 2g or 7.64 cm/s2...
This program displays the 3 axis output from an ADXL345 Accelerometer and 18F4550 in Hi-Tech C. Specifically the little GY-291 board available cheap on eBay. There are pull-ups on the board to solve the 3 volt problem.
I got some info from Ngoc Chung Hoang using CCS compiler ADXL345 + Pic...