What is Serial Peripheral Interface (SPI)?

A Serial Peripheral Interface (SPI) facilitates short-distance communication between peripheral integrated circuits and microcontrollers. In this article, we will understand the components of SPI, applications of Serial Peripheral Interface (SPI), and more.

What is SPI?

SPI stands for Serial Peripheral Interface. It is a protocol that is synchronous serial communication. It is used to communicate between the peripheral devices i.e. input and output devices and microcontrollers. It is allowed to transfer high-speed data. It is popular with digital communication applications and embedded systems. SPI can transfer the data and receive data from one device to another device at a time.

Components of SPI

Serial Peripheral Interface (SPI) is the process of synchronous serial communication protocol. It is mainly used for connecting the microcontrollers to peripheral devices like sensors, displays, and memory chips. It facilitates the full-duplex, synchronous serial communication between one or more slave devices and a microcontroller.

Components of SPI

• Master Device: The master device is nothing but it controls the process of transformation of data on the SPI bus. It controls the data flow and it generates the clock signal. In most of the applications, the master device is the microcontroller or specialized SPI controller.
• Slave Device: Slave devices are peripheral devices that are connected to the SPI bus and controlled by master devices. Every slave device has a different slave select (SS) line, allowing the master to select which device it wants to communicate with.
• SPI Bus: SPI bus is a physical connection over the data transferring between the slave devices and the master. It contains four signal lines as below.
  • Slave Select (SS): In Slave Select, each slave device contains a dedicated SS pin. If the master will communicate with the specific slave. Multiple slave devices can be shared with the as same as MOSI, MISO, and SCK lines but it must have separated SS lines.
  • Master Out Slave In (MOSI): In Master Out Slave In, MOSI can share the data or information from the master to other slave devices.
  • Master In Slave Out (MISO): In Master In Slave Out, MISO can share the data or information from the slave device with the master.
  • Serial Clock (SCK): In Serial Clock, this clock signal is used by the master and the slave devices for coordinating the data transfer timings.

• Data Transfer Protocol: SPI is used as a synchronous serial communication for simple transferring of data. The data is transferred and received at the same time in full duplex mode. By generating the clock pulses, the master-slave will initialize the transfer of the data. In every clock cycle, one bit of data will be transmitted both from master to slave and from slave to master directions.
• Data Rate: The SPI bus can support the different data transferring rates depending upon the master capabilities of the slave devices and the transmission line’s length. The data rate is specified in bits per megahertz (MHz) or second (bps).
• Clock Polarity (CPOL) and Clock Phase (CPHA): These are used to defined the relationship between the data signals and the clock signals. The data signals are nothing but, MOSI and MISO are called as the data signals. The SCK is called as the clock signal. There are available in four different possible combinations of CPHA settings and CPOL, they are allowing flexible to configuring to the SPI interface for work with the different devices.

Applications of Serial Peripheral Interface (SPI)

• Serial Peripheral Interface is a the communication protocol that finds the various domain of the applications for simplicity, capabilities of high speed transformation and flexibilities.
• SPI is extremely used for the Embedded Systems for the communication between the peripheral devices of the system and the microcontroller. Common applications are including the communicate with the sensors like temperature sensors, accelerometers, gyroscopes, actuators like motors and servos, memory devices like EEPROMs and flash memory, and displays like LCDs and OLEDs, etc.
• SPI can also be used for the Internet of Things (IOT) applications. It is employment to the connection of the microcontrollers or IOT modules to the various sensors and the actuators. Let us consider an example for the usage of IOTs in real world environment, SPI can used to interact with the environment sensors for the monitoring of the temperature such as humidity, and other usages of home appliances and industrial IoT applications.
• SPI can be mainly used in the Wireless communication modules to interface the microcontrollers with wireless communication devices like Wi-fi devices, Bluetooth devices. These types of devices required high-speed communication for transferring and receiving data without wire connection. SPI can provides the transferring data between the wireless devices and the microcontrollers.
• SPI can be commonly used for the Display Interface to employed in the various display types and also the graphical displays like Electrically Erasable Programmable Read-Only Memory (EEPROMs). SPI can be enabled to the sufficient to the reading and writing the data to non-volatile memory devices, it makes to suitable for the settings of the storing configuration, program codes, etc.

Advantages of Serial Peripheral Interface (SPI)

• High Speed Data Transfer: SPI can supports the high-speed communication, it is suitable for rapid data transferring applications. This data transfer is depends upon the some microcontrollers and used peripheral devices. The high speed data transfer can be used to the where the speed the communication will be needed such as the real time data acquisition or interfacing of the high-performance sensor.
• Simple Hardware Requirements: SPI required for the few hardware components. It consists of the four signal lines such as SCK, MOSI, MISO, SS and used for the data transmission by the no complex protocols. These requirements can be maintains the low hardware costs and implementation is easier compared to the other communication protocols.
• Full-Duplex Communication: SPI supports the full-duplex communication that means transferring and receiving the data enables the bidirectional communication. This bidirectional communication can be enabled to the sufficient transferring the data and making the suitable for the applications required for the high speed communication.
• Multi Slave Devices: SPIC can be supported the multiple slave devices using the single master device. Each slave device is assigned to the slave select (SS) line, for allowing to the master for needed to select and communicate with the single slave devices. This capability enabled to the SPI to the interface with the different multiple peripheral devices in the system without need any hardware requirements.
• Widespread Adoption: SPI is the protocol which is wide range adopted communication protocol within the embedded systems industries of the electronics, with the available for the most support of the microcontrollers and the peripheral devices. This adaption can be ensured the compatibility between the different hardware components. This adaption can makes the SPI is reliable choice for the communication in a variety of the applications.
• Low Overhead: SPI have low overhead compared to the other communication protocols. And it do not require the complex addressing or data packetization. This low overhead reduces simplified the software implementation. Making SPI suitable for the applications which are limited processing resources.
• Flexible Configurability: SPI can be offered the flexible in configuration parameters like clock polarity (CPOL) and clock phase (CPHA) for the accommodation of the different types of peripheral devices. This configuration allowed to the SPI to the interface with the large range of devices such as sensors, memory chips, displays and other integrated circuits without the required significant changes to the software or hardware.

Conclusion

The Serial Peripheral Interface (SPI), is a versatile and the efficient to the communication protocol utilization of the embedded systems, IoT devices, automotive electronics, etc. It have capabilities of high-speed data transfer, flexible with the preferred choice for the interfacing the microcontrollers with the peripheral devices in different applications. SPI can supported the full-duplex communication and offered to the configurable parameters like clock polarity and its widespread adaption.