The best option is to use an encoder. You would attach an encoder to the shaft that rotates, and would not only be able to tell when it is at the endpoints, but exactly where it is, to a far higher degree of accuracy than would be possible with a gyro or accelerometer. You could even pair this with a PID loop to get it to hold position, we implemented something similar here:
https://github.com/FRC1458/turtleshe...wigIntake.java.
If you would like additional information about the ADXL345, the original data sheets can be found here:
http://www.analog.com/en/products/me...oduct-overview.