The Serial Peripheral Interface Bus or SPI (often pronounced "es-pē-ī" [IPA: ɛs pi: 'aɪ] or "spy" [IPA: spaɪ]) bus is a synchronousserial data linkstandard named by Motorola that operates in full duplex mode. Devices communicate in master/slave mode where the master device initiates the data frame. Multiple slave devices are allowed with individual slave select (chip select) lines. Sometimes SPI is called a "four wire" serial bus, contrasting with three, two, and one wire serial buses.
