FMC 1-wire temp. sensor needs to use Vadj for I/O
Since the temperature sensor is connected to an FMC user I/O pin, it needs to be powered by Vadj. However, the DS18B20 IC needs at least 3.0V to work (pullup supply voltage > 3.0V, p. 19, datasheet), while we need to support a Vadj of 2.5V. Some kind of level shifting between 3.3V and Vadj needs to be added, possibly like what is commonly used for I2C.