I2C, or Inter Integrated Circuit, is a half-duplex hardware protocol that uses two conductors, one clock (SCL) and one data (SDA) line, to connect two or more devices. One device, designated the master, uses the clock signal to synchronize data transfer to one, or multiple, slave devices at speeds up to 400 Kbps. Typical logic levels are 5V or 3.3V for a high bit, and 0V for a low, making this an attractive option for embedded applications. I2C supports multiple slave devices by providing each with a one byte read and write address. Networks for this protocol typically span short distances due to a lack of robustness to noise.