Internal analog ref vs A4 and A5 SCL/SDA pin.


On my arduino uno + Deek-robot logger shield, I want to use 3.3volt analog ref instead of 5 volt but on the logger shield SCL and SDA are connected to analog pin 4 and 5. I use those pin for sensors (MPRLS and BME280). If I change the analog ref to 3.3volts, will it interfere with scl/sda and mess up my other sensor?

Same question but what if I connect the Aref pin to 1.5volts and use this as the analog ref?

thank you

I bump this up.

Can I hook a voltage divider to have 0.1 V external analog ref to the arduino uno and gain better resolution on my on pin A0, A1 and A2?

And most important, will this interfere with my I2C sensors hooked up on analog pin A4 and A5 (SCL / SDA)? Or maybe I can declare the Pin state in my setup?
While at it, can we use external ref for a said pin and internal ref for another pin simultaneously or we need to program the ref (external vs internal) between 2 acquisition?

My voltage divider would be composed of R1 = 1 meg, R2 = 22 k. The output would then be about 0.1 V and the total current flowing from 5 volt to ground would be a reasonnable 5 uA.

My alternative is to hook up a HX711 but If I can avoid the codding associated it would be great.

Thank you

Regarding your first question, the analogue reference will not interfere with your I2C.

Not sure if I know the answer to the second question.

IIRC the reference voltage should be at least 1V (there is a value in the datasheet). I think you need “low impedance” reference. SAR ADCs pull short bursts of “high current” from the reference. Ofc you can use a cap to cover this