Hi! I'm new to electronics so sorry for this simple question. I'm building an APRS tracker for a high altitude balloon project and I'm working with a BMP390 sensor.

I'm a little confused with why there's a difference between VDD and VDDIO when the voltage range is very similar. They both have a max of 3.6V but a slightly different minimum voltage. Can I attach the same 3.3V source (within range) to both the VDDIO and the VDD power input?

I'm also unsure why the SCK and the SDI pins need to be connected to VDDIO. For example: should I connect the SDI pin to both the SDA and a 3.3V source or could I connect the SDI pin to just the SDA pin on my ATSAMD28 microcontroller? Reading the microcontroller datasheet, the pins should be able to provide 3.3V?

 

Whether you can connect them together depends on what you are interfacing to. The main reason for having the separate IO supply is if you are interfacing to something that uses a difference supply voltage that you are running the sensor itself at. Also, be sure to carefully read how you select which interface protocol you are using.

 

Whether you can connect them together depends on what you are interfacing to. The main reason for having the separate IO supply is if you are interfacing to something that uses a difference supply voltage that you are running the sensor itself at. Also, be sure to carefully read how you select which interface protocol you are using.

Thanks that makes sense to me

 

Are you certain that the "Vddio" is a voltage supply input? In that case it could be the supply for the pull-up resistors for the external I/O circuit. Since it appears that there is also a manual describing the application of the module, there should be a specification for the voltage range acceptable for that terminal, as well as a mention of if it is an input for the pull-up voltage.

 

Are you certain that the "Vddio" is a voltage supply input? In that case it could be the supply for the pull-up resistors for the external I/O circuit. Since it appears that there is also a manual describing the application of the module, there should be a specification for the voltage range acceptable for that terminal, as well as a mention of if it is an input for the pull-up voltage.

Yes, "VDDIO" is a voltage supply input for the internal sensor logic level converter. Very common on digital sensor chips to match internal voltage requirements to the system logic driving it.

https://forum.allaboutcircuits.com/...tter-for-this-application.193257/post-1823342


For this board the VDD and VDDIO voltage levels are the same at 3.3vdc so they are simply cross connected.

 

OK, if it is indeed another isolated power input for I/O that does make sense. It is much better to verify than to be incorrect.