Introduction to SPI Protocol

Hello, readers welcome to the new post. Here we will discuss Introduction to SPI Protocol. SPI stands for a serial peripheral interface that is a communication protocol used for communication for small distances such as in embedded systems like microcontrollers. It was first time used in mid of the 1980s and was created by Motorola. This protocol communicates with the use of full-duplex mode and master-slave configuration that has one master or control device.

More than one salve or output device can be connected to this module through use of the slave select line. SPI is also called 4 4-wire serial bus.It can also be defined as a synchronous serial interface but not the same as the SSI or synchronous serial interface that also uses four wires. In this post, we will discuss different paramerts of SPI protocols in detail. So let’s get started.

Introduction to SPI Protocol

• It is a commonly used communication four-wire system employed in numerous projects and embedded systems.
• Examples of devices that use SPI protocols such as wireless systems, RFID  card readers SD card readers.

• Its main advantage is that it transmits the data without any hindrance.  Different quantities of data bits can be transmitted and received in serial form.
• While in other communication protocols such as UART and I2c send and receive data through use of packets and has some restrictions.
• It is subnode configured synchronous interfacing.

• In the above figure, some terms are used that’s explanation is given

• MOSI is the master output slave input it uses to send data to the slave
• MISO indicates master input slave output it used for sending data to the master from the slave
• SCLK clock used for clock signal
• SS/CS that is slave select chip select it helps to mater to choose which slave to use for the transmission of data.

Featues of SPI Communication Protocol

• Some features of this protocol are discussed here
• It consists of four wires for communications
• Data transfer speed for this protocol is about ten megabytes per second
• It is a synchronous protocol
• It also uses a serial communication system
• It has one master device and numerous slave devices can be connected.

Some other features are

4-Wire Interface:

• SPI comes with 4 wire interfacing that is serial clock (SCLK),  master in slave out (MISO),  master out slave in (MOSI), and slave select (SS) lines.
• This four-wire interfacing helps to provide 4 duplex communication providing same-time transmission and reception.

Master-Slave Architecture:

• SPI working based on master-slave configuration. The single master device regulates the clock and starts data transferring and slave work on the instructions of master devices. This design provides easy communication for devices.

Full-Duplex Communication:

• SPI is full duplex protocol. That shows that data is transmitted and received at the same time and provides high-speed data exchange.

High-Speed Data Transfer:

• SPI offers high-speed data transfer. The read data rate is based on certain features and master clock speed. SPI-supported data rates about many megabits per second. So best to use high-speed data transmission.

No Acknowledgment System:

• SPI does not have an acknowledgement system but data is corrected through the working of slave devices or with distinct hand-shaking signals.

Multiple Slave Support:

• SPI is compatible with different slave devices. and each device comes with an SS line that the master can pull low for communication. it is best for complicated system having different devices.

Working on SPI Protocol

• To send and receive data bust master arranges a clock through the use of frequency comported with slave modules to certain megahertz
• Master chooses the slave module through the use of logic level zero at the select line.
• Some delays are needed in different operations such as the ADC master adding some delay to send the clock signal
• Through the use of a very SPI clock signal, full-duplex communication is used for data transmission.
• Data in form of bit at the MOSI line is sent by the master read but the slave device. and Master gets the bit through the MISO line and reads it
• 2 shift registers have some word size is employed like 8 bits one for master and one for slave.
• Data transferred through the use of the most important bit firstly
• At the clock point master and slave shift the bit and send to result in a portion.
• At the side at every receiver point bit is sampled through the transmission line and adjusted in a less important bit at the shift register

 Data Transmission in SPI

• Some steps are followed for data transmission in the SPI

SPI Advantages

The main advantages of SPI are discussed here

• It is a duplex communication protocol
• Used of a push-pull driver in this module offered high-speed operation
• Its speed is higher than I2C and does not depend don’t the extreme clock speed.
• It does not need eight-bit words
• Its structure is simple
• It uses less power to operate than other modules
• Its hardware structure is very easy to make
• Slave devices use the master signal and not require precision oscillators
• It does not need a certain address like other protocol
• It is a four-pin module
• Any software can be easy to use on it

SPI DisAdvantages

• The main disadvantages of this protocol are discussed
• It needed more pins at the board than other protocols such as I2c
• It needed of band chip select signal
• It does not have hardware flow control at the slave
• It can have a single master device
• There is no configuration of error interruption
• It does not fulfill the hot-swapping
• Another category of SPI is half-duplex such as dual SPI Quad SPI

SPI Applications

• Common applications of SPI are described here
• It is used in different types of sensors such as pressure ADC temperature video game controllers
• It is used in DAC, audio codes that are a control device
• Used in lenses of a camera
• It is used in different communication systems such as USB, Ethernet CAN
• It consists of flash memory
• Real-time clocks

Faqs

That is all about the SPI protocol that has been discussed in detail. If you have any further queries ask in the comments. Thanks for reading