SPI vs I2C

  Digital Communication   Mar 31, 2024   0   370  Add to Reading List

1. SPI and I2C

SPI (Serial Peripheral Interface) is a full-duplex protocol with separate data, clock, and select lines, offering faster communication at short distances, suitable for high-speed devices like sensors and displays.

I2C (Inter-Integrated Circuit), a half-duplex protocol, utilizes shared clock and data lines, offering simpler hardware requirements and multi-master capability, suitable for longer distances with devices like EEPROMs and RTCs, albeit at slower speeds.

2. SPI vs I2C

  • Structure

I2C : 2 pin need,Half-duplex with shared Clock (SCL) and Data (SDA) lines

         SPI : 4 pins needed for Full-duplex with separate Data (MOSI/MISO), Clock (SCLK), and Slave select (SS)/Chip Select (CS) lines.

  • Speed

I2C : Slower and, up to 3.4 Mbps

SPI : Faster, several Mbps (10-100 Mbps is common)

  • Complexity

I2C : More complex due to slave addressing and arbitration as all slave using the same lines

SPI : Relatively simpler to implement, but need more pins to implement.

  • Distance

I2C : Suitable for longer distances

SPI : Suitable for short distances

  • Noise Immunity

I2C : Suitable for longer distances

SPI : Less immune to noise

  • Device Support

I2C : Low-speed peripherals like EEPROMs, RTCs

SPI : High-speed devices like sensors, displays

Aspect SPI I2C
Structure 4 pins needed for Full-duplex with separate data (MOSI/MISO), clock (SCLK), and select (SS) lines. 2 pin need,Half-duplex with shared clock (SCL) and data (SDA) lines
Speed Faster, several Mbps (10-100 Mbps is common) Slower and, up to 3.4 Mbps
Complexity Relatively simpler to implement, but need more pins to implement. More complex due to slave addressing and arbitration as all slave using the same lines
Hardware Pins Requires more pins Requires fewer pins due to shared lines
Distance Suitable for short distances Suitable for longer distances
Noise Immunity Less immune to noise More immune to noise
Device Support High-speed devices like sensors, displays Low-speed peripherals like EEPROMs, RTCs

3. Reference links 

SPI https://embeddedwala.com/Blogs/DigitalCommunication/Getting-Started-with-SPI:-A-Beginners-Guide
I2C https://embeddedwala.com/Blogs/DigitalCommunication/Getting-Started-with-I2C:-A-Beginners-Guide

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