The SPI interface

There is another type of serial communication interface named the Serial Peripheral Interface (SPI). This interface has to be enabled via raspi-config (this is similar to enabling serial port interface earlier in this chapter). Using the SPI interface is similar to that of I²C interface and the serial port.

Typically, an SPI interface consists of a clock line, data-in, data-out, and a Slave Select (SS) line. Unlike I²C communication (where we could connect multiple masters), there can be only one master (the Raspberry Pi Zero), but multiple slaves on the same bus. The SS pin enables selecting a specific sensor that the Raspberry Pi Zero is reading/writing data when there are multiple sensors connected to the same bus.

Example 4 - writing to external memory chip

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