1 SPI: Serial Peripheral Interface

SPI is a synchronous serial communication interface specification used for short-distance communication, primarily in embedded systems.

Salient features of SPI protocol are listed below:

• Serial interface
• Synchronous
• Master-slave configuration
• Data Exchange - DMA/PIO

The SPI bus specifies four logic signals:

• SCLK: Serial Clock (output from master)
• MOSI: Master Out Slave In (data output from master)
• MISO: Master In Slave Out (data output from slave)
• CS /SS: Chip/Slave Select (often active low, output from master to indicate that data is being sent)

MOSI on a master connects to MOSI on a slave. MISO on a master connects to MISO on a slave.

Slave Select has the same functionality as chip select and is used instead of an addressing concept.