OK, the barometric pressure finally worked without using any resistor or logic level sifters.
The same did the temperature sensor. These work with no problem with the real time module.
The problem is now with the 9dof IMU stick. When the real time module runs and just prints
the current time, I connect the SDA and SCL of the stick and the transfer freezes.
If I reset the board it sends me back some other time and when I disconnect the IMU the right time
comes back again.
Has anyone worked with these two modules? Any suggestion to look for?