I have used several of the FriendElec CPUs (NanoPi Fire3, NanoPC T4, NanoPi NEO4, plus others) and for the first time, I have to access an I2C device. I am running Ubuntu 18.04.2 LTS I can open the /dev/i2c-2 device and set the device address but I get compile errors as none of the i2c_smbus functio...