- SCLK : Serial Clock (output from master).
- MOSI : Master Output, Slave Input (output from master).
- MISO : Master Input, Slave Output (output from slave)
SS On both Raspberry Pi and chip pro, the process is called Chip Select, abbreviated CS, and the CS lines are referred to as Chip Enable lines, abbreviated CE. The PI actually makes two slave select lines available identified as CE0 and CE1.