Hello, my company is using an ADXL372 in a project and we are having some issues with wake up mode. Our goal is for the acclerometer to stay in wake up mode until sensing activity over some threshold (~2 g's, but this shouldn't matter), and upon sensing that activity firing INT1 where our MCU changes the acclerometer to full measurement mode and clears the interrupt. In full measurement mode upon sensing activity over a different higher threshold (~30 g's), it fires INT1 which is handled by our MCU and upon detecting inactivity for some time (~1-5 minutes) going back to wake up mode and starting again. All interrupts are cleared by our MCU.
Currently we are having a problem with the device in wakeup mode. Essentially it appears that it stays in wakeup mode with low current consumption for an amount of time based off the wakeup timer, and then goes into full measurement mode, then goes back to wakeup mode. This has been verified by monitoring the systems current consumption and changing the wakeup rate to confirm it stays in wakeup mode for the specified time. The amount of time it appears to be in high power mode does not appear to change based off the wakeup rate. This is a problem as the main goal for this project is ultra low power consumption (its why we chose the 372) and when it switches from wakeup to full measurement the current consumed by the whole system goes from ~7-8 uA to 22 uA, and this would effectively half our battery life.
Below are our configuration settings for both wake up and full measurement mode. Currently we have no issues with full measurement mode although it appears to draw significantly higher current than we are expecting. Any register not listed is set to its default value, threshold registers have been omitted as based off of our understanding that shouldn't affect the current consumption or operation of either mode, just change how much activity it takes to change them. Also, when we enable both filters, the system appears to stay in wakeup mode longer than with the filters disabled.
We are less concerned about our thresholds and timing settings and most concerned about our understanding of wake up mode and ensuring that it can meet our needs. Our goal is ultra low power detection of activity around 1.5-3 g's in wakeup mode and having the 372 fire an interrupt when that occurs.
Please let me know if there is any other information needed from me.
Sorry for the delayed response. Thank you for your use of ADXL372. I'll relay this to the team and get back to you in a while.