SPI Interface

SPI InterfaceSPI is a popular interface for consecutive data exchange between microcircuits. Along with I2C SPI interface is used for connecting microcircuits. It is one of the most widely used types of interface.An SPI bus has a master-slave type of design. The master device is usually a microcontroller. However this can also be a programmable logic a DSP controller or a special integrated circuit.The peripherals connected to the master of the bus are the slave devices. These can be various microcircuits including such memory devices as EEPROM Flash-memory and SRAM as well as real time clocks analogue-to-digital and digital-to-analogue converters digital potentiometers specialised controllers etc.The main module of the SPI interface is a regular shift register. Its synchronisation signals as well as bitstream inputs and outputs create the interface signals.Thus rather than calling SPI a link protocol it will be more appropriate to call it a communications protocol for exchanging data between two shift registers. Each shift register simultaneously serves as a receiver and a transmitter. Bus synchronisation signal is necessary in order to exchange data over an SPI bus.Only the master device of the bus has the permission to generate the signal. The work of the slave entirely depends on it.Four types of digital signals are used in SPI:MOSI or master out slave in signal used for transmission of data from the master device to the slave.MISO or master in slave out signal used for transmission of data from the slave device to the master.SCLK or serial clock this is a sequential clock signal serving for transmission of cadence for slave devices.And CS or SS meaning chip select and slave select accordingly. These signals serve for choosing a microcircuit or a slave device.,

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