cancel
Showing results for 
Search instead for 
Did you mean: 

How many times can "RPDS" register be written in the ILPS28QSW?

RPerez
Associate

I'm trying to use ILPS28QSW as a water level sensor. For that I want to convert the pressure into mmH2O. In order to make that conversion as easy as possible I'd like to substract the atmosferic pressure. The datasheet shows that there are two registers "RPDS_L" and "RPDS_H" that are used in the "one point calibration", but the datasheet says "To give better flexibility to the user, the OPC value can be written twice in the same register map.". I don't know if that means that after being written two times it's not possible to write them ever again, if so I'd need another way because there is a chance that I need that calibration to be made multiple times. Maybe I'm misunderstanding what that sentence means, but as I don't know what type of non volatile memory is, I don't really understand how that memory works. I've seen the application note AN5778 but found nothing related to this topic.

 

I've seen that there is a mode called "AUTOZERO" that makes more or less what I want, but that wouldn't be valid for me because I'd need to get the sensor out of the water, what wouldn't be possible. This mode stores the pressure in the "REF_P_L" and "REF_P_H" register. The register address map shows that these two registers can't be written, so I guess that there is no way for me to use them to substract the atmosferic pressure without getting it out of the water.

 

What would be the best way to make this callibration? Thanks

1 REPLY 1
Federica Bossi
ST Employee

Hi @RPerez ,

Welcome to ST Community!

OPC also called one point calibration is a register that save value @1Pa (atmospheric pressure) to re-align the device. After two times is not possible re-write again. In your application, the good solution is to have two pressure sensors. One used to measure external pressure and second to use the pressure into the liquid. Possible solution is to use ILPS28QSW and LPS22HH for atmospheric pressure.

If my reply answered your question, please click on Accept as Solution at the bottom of this post. This will help other users with the same issue to find the answer faster

In order to give better visibility on the answered topics, please click on 'Accept as Solution' on the reply which solved your issue or answered your question.