Document created by analog-archivist on Feb 23, 2016
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### 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