LPS25H differential mode

[andrea6388]

Posted on August 03, 2015 at 12:37

Good morning,

I'm trying to set up a LPS25H sensor to read the same value as another one, which is the reference, in a controlled environment. My first guess has been to set up REF_P registers as the difference between readings from the 2 sensors which is initially stored by firmware. I set up REF_P registers, I enable the DIFF_EN bit in CTRL_REG1 (while sensor is disabled) and finally I enable the sensor again.The problem is that measures coming from sensors still differ for the same amount of pressure,  while if I subtract the previously evaluated difference by firmware readings are very near.Could someone please describe the correct procedure to setup differential mode?Thank you,Andrea

[Nickname3482_O]

Posted on August 05, 2015 at 15:23

Hello Andrea,

after DIFF_EN you should enable AUTO_ZERO, then set your REF_P and run your measurement. AUTO_ZERO gets enabled setting writing 1 into bit 1 of CTRL_REG2 (at address 0x21).

Best Regards,

Adalberto

[andrea6388]

Posted on August 05, 2015 at 16:49Thank you Adalberto,as soon as possible I'll check the procedure.Andrea

[pfeiferm]

Posted on December 21, 2015 at 00:51

Hello,

I have a similar problem. I'm trying to use the LPS25HB pressure-sensor sensor in differential mode with my own settings in the REF_P registers. As Adalberto suggested, I tried to first enable DIFF_EN, than AUTOZERO and after that setting the REF_P registers. But it seems that my settings of REF_P are irgnored and only the auto-copy-values form the AUTOZERO-enable are stored, because the sensor-output is always around 0 afterwards (independent of which value I've written in REF_P). Am I doing something wrong? Or is there an other solution for that? Andrea, did you solve your problem? Thank you, Marc

[Nickname3482_O]

Posted on December 22, 2015 at 19:31

Hello Marc,

proceeding step by step : first set DIFF_EN bit then enable your sensor with a given ODR, at this point you will see ordinary measurements. Next set AUTOZERO, if everything is correct this is the point where you will see an allmost 0 ouput as consequence of initial pressure value being automatically copied in REF_P registers. Only after you get here REF_P registers can be overwritten with a value of you own choice. Regards, Adalberto