SPI (Serial Peripheral Interface)


SPI is serial communication protocol used by microcontrollers and sensors. It is widely used to due to its simplicity and ability to operate at high data rates. However there are several disadvantages like, only single master is supported, slaves can not communicate to each other, number of wires used increases with slaves connected. Disregarding these drawbacks SPI is commonly used in sensor devices because of the low complexity. Following diagram shows the typical connections used in SPI

Figure1: SPI connections


One drawback of connection shown in Figure1 is that Master needs to have a unique IO pin for each slave. An alternative method to interconnect is to use daisy chain. This would be specially useful when a microcontroller is driving a RGB led strip where individual LED colors are controlled by data sent via SPI.

Signal Description
SCK Clock signal driven by master
MISO Master in – Slave out
MOSI Master out – Slave in
SS Slave select



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