Address values Seems to be 7 bit value with bit0=lower bit (not I2C RW bit), so left shifted by 1 when sent over the wire. Master I2C Address Arduino addresses are 7 bit (excluding RW bit), so I2C byte address 0x40 needs to be changed to 0x20 for arduino functions. Clock Speed https://www.arduino.cc/en/Reference/WireSetClock