Avalon® Interface Specifications

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ID 683091
Date 9/03/2025
Public
Document Table of Contents
Document Table of Contents x
1. Introduction to the Avalon® Interface Specifications 2. Avalon® Clock and Reset Interfaces 3. Avalon® Memory-Mapped Interfaces 4. Avalon® Interrupt Interfaces 5. Avalon® Streaming Interfaces 6. Avalon® Streaming Credit Interfaces 7. Avalon® Conduit Interfaces 8. Avalon® Tristate Conduit Interface A. Deprecated Signals B. Document Revision History for the Avalon® Interface Specifications
1. Introduction to the Avalon® Interface Specifications x
1.1. Avalon® Properties and Parameters 1.2. Signal Roles 1.3. Interface Timing 1.4. Example: Avalon® Interfaces in System Designs
2. Avalon® Clock and Reset Interfaces x
2.1. Avalon® Clock Sink Signal Roles 2.2. Clock Sink Properties 2.3. Associated Clock Interfaces 2.4. Avalon® Clock Source Signal Roles 2.5. Clock Source Properties 2.6. Reset Sink 2.7. Reset Sink Interface Properties 2.8. Associated Reset Interfaces 2.9. Reset Source 2.10. Reset Source Interface Properties
3. Avalon® Memory-Mapped Interfaces x
3.1. Introduction to Avalon® Memory-Mapped Interfaces 3.2. Avalon® Memory Mapped Interface Signal Roles 3.3. Interface Properties 3.4. Timing 3.5. Transfers 3.6. Address Alignment 3.7. Avalon® -MM Agent Addressing
3.5. Transfers x
3.5.1. Typical Read and Write Transfers 3.5.2. Transfers Using the waitrequestAllowance Property 3.5.3. Read and Write Transfers with Fixed Wait-States 3.5.4. Pipelined Transfers 3.5.5. Burst Transfers 3.5.6. Read and Write Responses
3.5.2. Transfers Using the waitrequestAllowance Property x
3.5.2.1. waitrequestAllowance Equals Two 3.5.2.2. waitrequestAllowance Equals One 3.5.2.3. waitrequestAllowance Equals Two - Not Recommended 3.5.2.4. waitrequestAllowance Compatibility for Avalon® -MM Host and Agent Interfaces 3.5.2.5. waitrequestAllowance Error Conditions
3.5.4. Pipelined Transfers x
3.5.4.1. Pipelined Read Transfer with Variable Latency 3.5.4.2. Pipelined Read Transfers with Fixed Latency
3.5.5. Burst Transfers x
3.5.5.1. Write Bursts 3.5.5.2. Read Bursts 3.5.5.3. Line–Wrapped Bursts
3.5.6. Read and Write Responses x
3.5.6.1. Transaction Order for Avalon® -MM Read and Write Responses (Hosts and Agents) 3.5.6.2. Avalon® -MM Read and Write Responses Timing Diagram
3.5.6.2. Avalon® -MM Read and Write Responses Timing Diagram x
3.5.6.2.1. minimumResponseLatency Timing Diagram with readdatavalid or writeresponsevalid
4. Avalon® Interrupt Interfaces x
4.1. Interrupt Sender 4.2. Interrupt Receiver
4.1. Interrupt Sender x
4.1.1. Avalon® Interrupt Sender Signal Roles 4.1.2. Interrupt Sender Properties
4.2. Interrupt Receiver x
4.2.1. Avalon® Interrupt Receiver Signal Roles 4.2.2. Interrupt Receiver Properties 4.2.3. Interrupt Timing
5. Avalon® Streaming Interfaces x
5.1. Terms and Concepts 5.2. Avalon® Streaming Interface Signal Roles 5.3. Signal Sequencing and Timing 5.4. Avalon® -ST Interface Properties 5.5. Typical Data Transfers 5.6. Signal Details 5.7. Data Layout 5.8. Data Transfer without Backpressure 5.9. Data Transfer with Backpressure 5.10. Packet Data Transfers 5.11. Signal Details 5.12. Protocol Details
5.3. Signal Sequencing and Timing x
5.3.1. Synchronous Interface 5.3.2. Clock Enables
5.9. Data Transfer with Backpressure x
5.9.1. Data Transfers Using readyLatency and readyAllowance 5.9.2. Data Transfers Using readyLatency
6. Avalon® Streaming Credit Interfaces x
6.1. Terms and Concepts 6.2. Avalon® Streaming Credit Interface Signal Roles 6.3. Avalon® Streaming Credit User Signals
6.2. Avalon® Streaming Credit Interface Signal Roles x
6.2.1. Synchronous Interface 6.2.2. Typical Data Transfers 6.2.3. Returning the Credits
6.3. Avalon® Streaming Credit User Signals x
6.3.1. Per-Symbol User Signal 6.3.2. Per-Packet User Signal
7. Avalon® Conduit Interfaces x
7.1. Avalon® Conduit Signal Roles 7.2. Conduit Properties
8. Avalon® Tristate Conduit Interface x
8.1. Avalon® Tristate Conduit Signal Roles 8.2. Tristate Conduit Properties 8.3. Tristate Conduit Timing
1. Introduction to the Avalon® Interface Specifications
2. Avalon® Clock and Reset Interfaces
3. Avalon® Memory-Mapped Interfaces
4. Avalon® Interrupt Interfaces
5. Avalon® Streaming Interfaces
6. Avalon® Streaming Credit Interfaces
7. Avalon® Conduit Interfaces
8. Avalon® Tristate Conduit Interface
A. Deprecated Signals
B. Document Revision History for the Avalon® Interface Specifications

3.5.2.3. waitrequestAllowance Equals Two - Not Recommended

The following diagram illustrates timing for an Avalon® -MM host that can send two transfers after waitrequest is asserted.

This timing is legal, but not recommended. In this example the host counts the number of transactions instead of the number of clock cycles. This approach requires a counter that makes the implementation more complex and may affect timing closure. When the host determines when to drive transactions with the waitrequest signal and a constant number of cycles, the host starts or stops transactions based on the registered signals.

Figure 10. waitrequestAllowance Equals Two Transfers

The numbers in this figure mark the following events:

  1. The Avalon® -MM host asserts write and drives data.
  2. The Avalon® -MM agent asserts waitrequest.
  3. The Avalon® -MM host drives write and data. Because the waitrequestAllowance is 2, the host drives data in 2 consecutive cycles.
  4. The Avalon® -MM host deasserts write because the host has spent the 2-transfer waitrequestAllowance.
  5. The Avalon® -MM host issues a write as soon as waitrequest is deasserted.
  6. The Avalon® -MM host drives write and data. The agent asserts waitrequest for 1 cycle.
  7. In response to waitrequest, the Avalon® -MM host holds data for 2 cycles.
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