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How AXI Works?

Published in Bus Protocol 2 mins read

The AXI (Advanced eXtensible Interface) protocol facilitates communication between a master and a slave device.

Basic AXI Communication

In its most fundamental setup, AXI creates a channel for data transfer between a single master device and a single slave device.

  • Master: The master device initiates a data request and manages the communication process.
  • Slave: The slave device responds to the master's requests by providing the required data or performing the necessary action.

Communication Flow

The AXI protocol operates using several channels to handle different aspects of the communication:

  1. Address Channel (Write & Read):
    • The master sends the address to the slave device indicating where the data transfer should occur.
  2. Write Data Channel:
    • The master sends the actual data to be written to the slave.
  3. Write Response Channel:
    • The slave sends acknowledgment back to the master, confirming successful write operation.
  4. Read Data Channel:
    • The slave responds by sending the requested read data to the master.
  5. Read Response Channel:
    • The slave send information regarding the data transfer including data validity.

Example Scenario

Step Action Master Slave Channel
1 Request Write Sends address & data intended for write Address & Write Data
2 Write Acknowledgement Acknowledges successful write operation Write Response
3 Request Read Sends address to read from Address
4 Send Requested Data Sends data requested by master Read Data
5 Read Data Acknowledgement Informs master regarding data status Read Response

Key Characteristics:

  • Handshake Protocol: AXI uses a handshake mechanism where the master signals its intent and the slave acknowledges to ensure proper data transfer. This helps maintain synchronization between master and slave.
  • Burst Transfers: AXI allows for burst transfers which means multiple data transfers with a single address request, thereby increasing efficiency.
  • Separate Read/Write: AXI operates read and write data transactions separately providing more flexibility.

Conclusion

AXI serves as an efficient and versatile interface for enabling data communication between master and slave devices, widely used in complex systems. It provides the necessary framework for devices to interact and exchange data with each other effectively using clearly defined communication channels and a handshaking mechanism.

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