SPI (Serial Peripheral Interface)

Overview

SPI (pronounced “spy”) is a widely used synchronous serial communication protocol, designed for high-speed data exchange between a master device and one or more slave devices.

Key Features

Four-Wire Protocol

  • MISO: Master In Slave Out.
  • MOSI: Master Out Slave In.
  • SCLK: Serial Clock.
  • CS: Chip Select (used to select a specific slave device).
  • Operates in full-duplex mode, allowing simultaneous data transmission and reception.

Bus Protocol

  • Uses the CS pin to select the desired slave device.
    • Pulls the pin low to select a slave
  • Capable of attaching multiple slave devices, where each device requires a unique CS pin.
  • Polarity and Phase of the signals can be configured by the host

Architecture

  • Single master configuration:
    • Only one device can control the communication bus at a time.
    • All communication is initiated by the master device.

Speed and Performance

  • Supports a maximum speed of approximately 8 Mbps.
  • Master defines speeds of data transfer

Applications

  • Primarily used for on-board communication between components.
  • Commonly used for communication with peripherals like the LoRa Module.

Benefits

  • High-speed and efficient data transfer.
  • Simple hardware interface requiring minimal wires.
  • Suitable for short-distance communication within a single board.

Drawbacks

  • Need an additional wire for each device
  • Can be sensitive to noise