Currently these three bridges are available. All three provide you extra I/O pins. SC16IS7xx is a high speed UART with I²C or SPI bus interface. You can choose between a SPI or I²C-based host bus connection with the bus mode pin. The SC18IS60x is an I²C Master controller with SPI host bus interface and the SC18IM700 is an I²C Master controller with UART interface. These devices offer a seamless interface to the host – no external components are required. The software is very simple and straight forward to write as the commands are just text in hex. These devices receive commands in hex from host, and they translate these commands to the actual electrical signals to communicate with other devices.