SPI abbreviation for Serial Peripheral Interface, SPI is Synchronous Serial Communication interface. Used for short distance communication developed By Motorola in 1980 after becomes defacto standard. SPI communication is full duplex communication mode. Its also called sometime Four Wire Serial Bus (FWSB). Contrasting with Three, Two and One Wire Serial Bus. Four wire protocol SCL, SS, MISO and MOSI. SPI is single master protocol.