Master

Device that provides the clock signal and determines the state of the slave select lines.

Slave

Device that receives the clock and slave select from the master.

SCLK

Serial Clock. Control line that is driven by the master and regulates the flow of the data bits.

MOSI

Master Out Slave In. This data line supplies output data from the Master which is shifted into the slave.

MISO

Master In Slave Out. This data line supplies the output data from a slave to the input of the master.

SS

Slave Select. Control line that allows slaves to be turned on and off with hardware control