If you have
ug8.whatever
you can just change by adding the 2, be sure to match the way it is worded on any of your other sketched.
fonts do matter. I do not believe that they are all supported back and forth between versions.
ug2.whatever
but everywhere, in the initial above setup
in setup and in every other location.
I would recomennd you open hellow world
and post my code snippet
then add your sensors and put in the variavbles as you need.
just one such as temperature would prove it out.
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#2 - the connection, I2c, SPI, whaterver is not relavant. the software that does the draw or print does not care.
but you need to make sure your constructor matches and you have any wire libraries, and such.
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#3, is my response #1
if you still have issues, I would recomend you post your code with the u8g2 lib
and tonite, I could try it out. I have a DH11 so that would make it simple .