Q
Could you tell me if it is possible to calibrate the ADXL345?
A
Calibration is done similar to any other accelerometer. Depending on how
calibrated you would like it to be. Basically, you would just place the part
flat, so 1 g in Z, 0 g in X and Y, determine the offset and then program the
opposite value into the OFFSET registers of the part. This would need to be
reprogrammed whenever the part is power-cycled though. If you want it to be
even more calibrated, you should also orient it such that there is a 0 g in the
Z-axis, to correctly calibrate the 0 g offset of Z, otherwise you assume an
ideal 256 codes and calibrate for that.
Sensitivity can be calibrated the same way. Position the sensor such that 1 g
is in the positive direction, say +X, record how many LSBs that is, then rotate
it so that 1 g is in the -X and record that. Half of the average value would
be the offset and half the sum of the absolute value of each would be the
sensitivity. i.e.
If +X was +270 LSB and -X was -250 LSB:
+270 + (-250) = +20 LSB
Offset would be +10 LSB
