SPI

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Serial Peripheral Interface Bus (SPI bus) Connects circuitry with few wires over serial protocol.

SPI supports an unlimited number of peripherals, which may all be identical.

Daisy-chained SPI connects all the devices on a SPI bus in a loop. In a daisy-chain SPI loop, the serial data out pin (SDO) of each device connected to the serial data in pin (SDI) of the next device in the loop. A daisy-chained SPI bus uses 4 GPIO pins on the microcontroller, no matter how many SPI peripherals are attached.


Chip-select SPI uses an additional dedicated chip-select pin for each SPI peripheral.


(Other protocols, such as I2C, require each peripheral on the bus to have a different (unique) address).


Further reading

Serial Peripheral Interface Bus