SPI: Advantages and Disadvantages

This page covers the advantages and disadvantages of SPI (Serial Peripheral Interface). It mentions the benefits and drawbacks of SPI, and also describes SPI interface basics.

What is SPI?

Introduction:

• SPI stands for Serial Peripheral Interface.
• It uses four lines for communication between a master and one or more slaves. These lines are:
  • MOSI (Master Out Slave In)
  • MISO (Master In Slave Out)
  • SCLK (Serial Clock)
  • SS (Slave Select)
• It supports data rates of approximately 10 to 20 Mbps. The maximum limit is not explicitly defined in SPI interface specifications.
• It’s a synchronous communication protocol, as a common serial clock is used between the master and the slave device(s).

SPI interface diagram

Benefits or Advantages of SPI

The following are the benefits or advantages of SPI:

• It is a very simple protocol, requiring minimal processing overhead. Designers primarily need to understand the read/write timing diagrams of the microcontroller/EPROM to use it effectively.
• It supports full-duplex communication.
• SPI uses a push-pull configuration, enabling higher data rates and support for longer distances.
• It consumes less power compared to the I2C interface.
• Data can be transferred at high speeds, in the tens of MHz range.

Drawbacks or Disadvantages of SPI

The following are the disadvantages of SPI:

• It requires one CS (Chip Select) line per slave device. This increases hardware complexity when multiple slave devices are present in the design.
• Adding a slave device necessitates software changes and the addition of an extra CS line.
• SPI lacks flow control and acknowledgment mechanisms.
• The master and slave relationships are fixed and cannot be altered dynamically, unlike I2C.
• The master may not inherently know whether a slave device is present or absent. Handshaking is typically required using software to address this.