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The Serial Peripheral Interface (SPI) bus is a synchronous serial communication interface specification used for short distance communication, primarily in embedded systems. The interface was developed by Motorola and has become a ''de facto'' standard. Typical applications include, Secure Digital cards, and liquid crystal displays. SPI devices communicate in full duplex mode using a master-slave architecture with a single master. The master device originates the frame for reading and writing. Multiple slave devices are supported through selection with individual slave select (SS) lines. Sometimes SPI is called a ''four-wire'' serial bus, contrasting with three-, two-, and one-wire serial buses. The SPI may be accurately described as a synchronous serial interface,〔(【引用サイトリンク】title= What is Serial Synchronous Interface (SSI)? )〕 but it is different from the Synchronous Serial Interface (SSI) protocol, which is also a four-wire synchronous serial communication protocol, but employs differential signaling and provides only a single simplex communication channel. ==Interface== The SPI bus specifies four logic signals: * SCLK : Serial Clock (output from master). * MOSI : Master Output, Slave Input (output from master). * MISO : Master Input, Slave Output (output from slave). * SS : Slave Select (active low, output from master). Alternative naming conventions are also widely used, and SPI port pin names for particular IC products may differ from those depicted in these illustrations: Serial Clock: * SCLK : SCK, CLK. Master Output --> Slave Input: * MOSI : SIMO, SDI(for slave devices), DI, DIN, SI, MTST. Master Input <-- Slave Output: * MISO : SOMI, SDO (for slave devices ), DO, DOUT, SO, MRSR. Slave Select: * SS : nCS, CS, CSB, CSN, EN, nSS, STE, SYNC. The MOSI/MISO convention requires that, on devices using the alternate names, SDI on the master be connected to SDO on the slave, and vice versa. Chip select polarity is rarely active high, although some notations (such as SS or CS instead of nSS or nCS) suggest otherwise. Slave select is used instead of an addressing concept. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Serial Peripheral Interface Bus」の詳細全文を読む スポンサード リンク
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