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ADXL345 - Configuring the Power register does not always work.

Question asked by milagorobets on Jun 17, 2013
Latest reply on Jul 5, 2013 by neilzhao

Good afternoon everyone,


I am working with an ADXL345 and I have intermittent issues configuring the power register (0x2D), everything else seems to function fine - when I get the power register correctly configured (to 0x08) all axis work, and my settings are fine (device ID is always right either way).


I am using SPI interface, and the clock is at 100kHz. I have tried different ADXL chips, but the problem seems to be with them all.


The 0x2D has a tendency to return 0x02 while I try to make it 0x08. I have checked my timing on an oscilloscope and it seems right. What I noticed though is that tapping the MO pin on the ADXL with my oscilloscope probe (usually when I want to watch the signal) fixes the problem and the 0x2D register configures fine. Could this be a problem with noise on one of the pins?


What is the recommended max length of wires between master and the ADXL pins? I'm powering the board from an ez430 board, and the supply voltage is ~3.5. I have the ADXL345EB board plugged into a small breadboard and wires feeding out to the microprocessor from there on.