I have an ADXL345 accelerometer and mounted it to a hybrid rocket to launch. Unfortunately, I forgot to set the range from its default of +/-2g to +/-8g (we expected 6g during liftoff).
For +/-2g range, the datasheet lists an output resolution of 10 bits, and for +/-8g it lists a resolution of 12 bits.
I noticed this in the datasheet linked above, under the
DATA_FORMAT register (0x31):
The DATA_FORMAT register controls the presentation of data to Register 0x32 through register 0x37. All data, except that for the +/-16g range, must be clipped to avoid rollover. (emphasis mine)
Based on this statement and the functional block diagram (a 3-axis sensor is connected to "sense electronics", then connected to an ADC), I am hoping there is a way to resolve the correct data. The scale factors are listed on page 3 of the datasheet.
Is there a way I can resolve this data, at least to 1 or 2 significant figures? (For instance, I have a detection of 1.9414g – this should be around 6). I don't think the sensor saturated, merely the number in the data registers – and given the scale factors and some creative bit-shifting (it is not totally clear how they get from 10 to 12 bits when changing resolution), hopefully I can recover something useful from my data.