We are using the LPS25HB for a Barometric sensor and I have been able to get temperature and pressure readings from the device as necessary with a 1Hz ODR.
We now want to use the threshold interrupts to allow our micro to go to sleep until the pressure changes bu more than a specified amount.
To do this I set the references value and the threshold deviation enable the interrupts and enable the Differential mode to generate the interrupts. However once differential mode is enable the Interrupt becomes continuously asserted, even though the pressure is still within the threshold.
The LPS25HB is still producing new values as I can seen small changes in the pressure.
There would appear to be some small inconsistencies in the datasheet over whether the PRESS_OUT registers show the measured value or a differential value. It even has a very clear block diagram showing that the PRESS_OUT register always contain the difference between the measure value and the REF_P register value. However this does not appear to be the case as changing the REF_P registers has no effect on the PRESS_OUT value.
This raise into question the accuracy and details of the entire description in the datasheet.
Are there additional operational and register control constraints that are not documented?
I cannot find any Application Notes or additional documentation on how to use the interrupts or differential mode.
Can anyone explain to me how to correctly use the interrupt and setup correct upper and lower pressure thresholds?
I should point out that my thresholds are not fixed. They will need to vary as new measurements are recorded by the micro.
Help appreciated.
Andrew.
