SPI (Serial Peripheral Interface) is a full duplex serial port where a master control the speed through selecting device and clocking the bus. Both master and slave send at the same time controlled by the clock ticked by Master. Modern MCU’s have a number of SPI’s implemented as IO and supported by DMA. Various SPI protocols are supported on chips making it easy to interface to hardware. From an user perspective SPI is a serial protocol with a byte stream in/out. Each hardware device have it’s own protocol so we need to maintain separate streams for each device.
Smart SPI used to communicate on a network will only allow Smart SPI enabled devices on that bus and it also require awareness of the protocol that makes implementation a bit special. This causes SPI to be implemented in a series of sub-modules:
| SPI |
Main class used to wire up an SPI port. The SPI instances is typically declared global and wired to the ports with supportive setting in GPIO. |
| SPIDevice |
Generic SPI Device Interface. This is typically used to connect to a general purpose SPI Network with one or more devices. Each device is optionally associated with a GPIO Ship Select pin. |
| SmartSPI | Smart SPI Master/Slave. Smart SPI requires some intelligence on low level to allow streams to flow to/from different devices without using Ship Select pins. |