About hor63

Don‘t even bother further with this design approach. It will never work. If you need to revise your PCB anyway dot it right with a differential sensor. My educated guess is that your two sensors are not on the same PCB but one is located within the box and the other outside because the Bosch sensors do not have hose connectors. This maens it is likely that either the power supply or the ambient temperature of both sensors vary when you switch on the fans. The imperfections of the temperature compensation for absolute pressure sensors alone easily explains the diverging of the measurements. ... View more

IMHO you have chosen a bad design from the start. the pressure difference is at the lower end of the resolution of the absolute pressure sensors. You should use a differential pressure sensor with an appropriate rage ( e.g. 100PA). Here your pressure difference is the full range of the sensor, and not a minuscule part like in your design. ... View more

Can you you reproduce the behavior with the first implementation with global variables?  It indicates a potential problem with your program, i.e. overwriting memory accidental from other parts of the program. You should follow up on that. With your changed design now other memory areas may get overwritten uncontrolled. if possible set a  break or watch point on any change to the variable which is changed unexpectedly, and let the program run. ... View more

What do you mean with delay? Each measurement is indicated in the status register immediately when the measured date is available. The status is available for each sensor independently. The only one causing delays is you when you miss reading out the measurements once they become available. You can trigger one of the interrupt lines to notify your MCU or processor instead polling. ... View more

Why not BMX160 instead of a combination of two devices BHI160 + BMM150 ... View more