mkahali:
I dont think always! at lease for pins A4 and A5, as you can see here:
YES YOU DO!! as you can see here:-
what does
put in the line in the keywords.txt file
mean?
In every library there is a file called keywords.txt - that file defines what words change colour.
I need to copy I2C library in the main library.
No you don't.
For the last time I tell you -: You use one board on the I2C hardware lines of A4 & A5
You use the other board on two digital lines that you designate as data and clock in a "software I2C" library.
Then as the BMP180 library uses the hardware I2C bus you have to hack a copy of the BMP180 library ( call it something else ) to use the "software I2C" library.
It is becoming increasingly clear that you are not able to do this project with your current state of knowledge and your unwillingness / inability to follow advice.