The Serial Peripheral Interface (SPI) is a communication bus that is used to interface one or
more slave peripheral integrated circuits (ICs) to a single master SPI device; usually a mi-
crocontroller ormicroprocessor ofsome sort. Note that the SPIpins are not connected to any
of the digital I/O pins as they are on the Uno, They are only available on the ICSP connector.
The following is a schema of ICSP connector.