Nios® V Processor Reference Manual

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ID 683632
Date 3/28/2022
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Document Table of Contents
Document Table of Contents x
1. About this Document 2. Nios® V/m Processor 3. Document Revision History for the Nios® V Processor Reference Manual
1. About this Document x
1.1. Overview
2. Nios® V/m Processor x
2.1. Processor Performance Benchmarks 2.2. Processor Pipeline 2.3. Processor Architecture 2.4. Programming Model 2.5. Core Implementation
2.3. Processor Architecture x
2.3.1. General Purpose Register File 2.3.2. Arithmetic Logic Unit 2.3.3. Control and Status Registers 2.3.4. Exception Controller 2.3.5. Interrupt Controller 2.3.6. Memory and I/O Organization 2.3.7. RISC-V based Debug Module
2.3.5. Interrupt Controller x
2.3.5.1. Timer and Software Interrupt Module
2.3.6. Memory and I/O Organization x
2.3.6.1. Instruction and Data Buses
2.3.6.1. Instruction and Data Buses x
2.3.6.1.1. Instruction Manager Port 2.3.6.1.2. Data Manager Port 2.3.6.1.3. Address Map
2.3.7. RISC-V based Debug Module x
2.3.7.1. Debug Mode 2.3.7.2. Halt from Debug Module 2.3.7.3. Debug Implementation 2.3.7.4. Abstract Commands in Debug Mode 2.3.7.5. Hardware/Software Interface
2.4. Programming Model x
2.4.1. Privilege Levels 2.4.2. Control and Status Registers (CSR) Mapping
2.4.1. Privilege Levels x
2.4.1.1. Machine Mode (M-mode) 2.4.1.2. Debug Mode (D-mode)
2.4.2. Control and Status Registers (CSR) Mapping x
2.4.2.1. Control and Status Register Field
2.5. Core Implementation x
2.5.1. Instruction Set Reference
1. About this Document
2. Nios® V/m Processor
3. Document Revision History for the Nios® V Processor Reference Manual

2.3.6.1.1. Instruction Manager Port

Nios® V/m processor instruction bus is implemented as a 32-bit AMBA* 4 AXI manager port.

The instruction manager port:
  • Performs a single function: it fetches instructions to be executed by the processor.
  • Does not perform any write operations.
  • Can issue successive read requests before data return from prior requests.
  • Can prefetch sequential instructions.
  • Always retrieves 32-bit of data. Every instruction fetch returns a full instruction word, regardless of the width of the target memory. The widths of memory in the Nios® V/m processor system is not applicable to the programs. Instruction address is always aligned to a 32-bit word boundary.
Table 8.  Instruction Interface Signals
Interface Signal Role Direction
Write Address Channel awaddr Unused Output
awprot Unused Output
awsize Unused Output
awready Unused Input
Write Data Channel wvalid Unused Output
wdata Unused Output
wstrb Unused Output
wlast Unused Output
wready Unused Input
Write Response Channel bvalid Unused Input
bres Unused Input
bready Unused Output
Read Address Channel araddr Instruction Address (Program Counter) Output
arprot Unused- tied off to constant value Output
arvalid Instruction request valid Output
arsize Constant 2- 4 bytes Output
arready From subordinate/interconnect Input
Read Data Channel rdata Instruction Input
rvalid Instruction valid Input
rresp Instruction response: Non-zero value denotes instruction access fault exception. Input
rready Constant 1 Output
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