Nios® V Processor Reference Manual

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ID 683632
Date 4/01/2024
Public
Document Table of Contents
Document Table of Contents x
1. Overview 2. Nios® V/c Processor 3. Nios® V/m Processor 4. Nios® V/g Processor 5. Nios V Processor Reference Manual Archives 6. Document Revision History for the Nios® V Processor Reference Manual
1. Overview x
1.1. Quartus® Prime Software Support
2. Nios® V/c 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. Reset and Debug Signals 2.3.4. Memory and I/O Organization 2.3.5. Error Correction Code (ECC)
2.3.4. Memory and I/O Organization x
2.3.4.1. Instruction and Data Buses 2.3.4.2. Address Map
2.3.4.1. Instruction and Data Buses x
2.3.4.1.1. Instruction Manager Port 2.3.4.1.2. Data Manager Port
2.4. Programming Model x
2.4.1. Privilege Levels
2.4.1. Privilege Levels x
2.4.1.1. Machine Mode (M-mode)
2.5. Core Implementation x
2.5.1. Instruction Set Reference
3. Nios® V/m Processor x
3.1. Processor Performance Benchmarks 3.2. Processor Pipeline 3.3. Processor Architecture 3.4. Programming Model 3.5. Core Implementation
3.1. Processor Performance Benchmarks x
3.1.1. Pipelined 3.1.2. Non-pipelined
3.2. Processor Pipeline x
3.2.1. Pipelined Architecture 3.2.2. Non-pipelined Architecture
3.3. Processor Architecture x
3.3.1. General-Purpose Register File 3.3.2. Arithmetic Logic Unit 3.3.3. Reset and Debug Signals 3.3.4. Control and Status Registers 3.3.5. Exception Controller 3.3.6. Interrupt Controller 3.3.7. Memory and I/O Organization 3.3.8. RISC-V based Debug Module 3.3.9. Error Correction Code (ECC)
3.3.6. Interrupt Controller x
3.3.6.1. Timer and Software Interrupt Module
3.3.7. Memory and I/O Organization x
3.3.7.1. Instruction and Data Buses 3.3.7.2. Address Map
3.3.7.1. Instruction and Data Buses x
3.3.7.1.1. Instruction Manager Port 3.3.7.1.2. Data Manager Port
3.3.8. RISC-V based Debug Module x
3.3.8.1. Debug Mode 3.3.8.2. Halt from Debug Module 3.3.8.3. Trigger 3.3.8.4. Abstract Commands in Debug Mode 3.3.8.5. Hardware/Software Interface
3.4. Programming Model x
3.4.1. Privilege Levels 3.4.2. Control and Status Registers (CSR) Mapping
3.4.1. Privilege Levels x
3.4.1.1. Machine Mode (M-mode) 3.4.1.2. Debug Mode (D-mode)
3.4.2. Control and Status Registers (CSR) Mapping x
3.4.2.1. Control and Status Register Field
3.5. Core Implementation x
3.5.1. Instruction Set Reference
4. Nios® V/g Processor x
4.1. Processor Performance Benchmarks 4.2. Processor Pipeline 4.3. Processor Architecture 4.4. Programming Model 4.5. Core Implementation
4.3. Processor Architecture x
4.3.1. General-Purpose Register File 4.3.2. Arithmetic Logic Unit 4.3.3. Multipy and Divide Units 4.3.4. Floating-Point Unit 4.3.5. Custom Instruction 4.3.6. Reset and Debug Signals 4.3.7. Control and Status Registers 4.3.8. Exception Controller 4.3.9. Interrupt Controller 4.3.10. Memory and I/O Organization 4.3.11. RISC-V based Debug Module 4.3.12. Error Correction Code (ECC)
4.3.4. Floating-Point Unit x
4.3.4.1. IEEE 754 Exception Conditions 4.3.4.2. Floating Point Operations
4.3.4.2. Floating Point Operations x
4.3.4.2.1. Floating Point Classification
4.3.9. Interrupt Controller x
4.3.9.1. Timer and Software Interrupt Module
4.3.10. Memory and I/O Organization x
4.3.10.1. Instruction and Data Buses 4.3.10.2. Address Map 4.3.10.3. Cache Memory 4.3.10.4. Tightly Coupled Memory
4.3.10.1. Instruction and Data Buses x
4.3.10.1.1. Instruction Manager Port 4.3.10.1.2. Data Manager Port
4.3.10.3. Cache Memory x
4.3.10.3.1. Instruction Cache 4.3.10.3.2. Data Cache 4.3.10.3.3. Configurable Cache Memory 4.3.10.3.4. Bypassing Cache (Peripheral Region) 4.3.10.3.5. Using Cache Memory Effectively
4.3.10.4. Tightly Coupled Memory x
4.3.10.4.1. Instruction and Data Tightly Coupled Memory 4.3.10.4.2. Accessing Tightly Coupled Memory Access from Processor Core Access from External AXI4-Lite Manager 4.3.10.4.3. Using Tightly Coupled Memory Effectively
4.3.11. RISC-V based Debug Module x
4.3.11.1. Debug Mode 4.3.11.2. Halt from Debug Module 4.3.11.3. Trigger 4.3.11.4. Abstract Commands in Debug Mode 4.3.11.5. Hardware/Software Interface
4.4. Programming Model x
4.4.1. Privilege Levels 4.4.2. Control and Status Registers (CSR) Mapping
4.4.1. Privilege Levels x
4.4.1.1. Machine Mode (M-mode) 4.4.1.2. Debug Mode (D-mode)
4.4.2. Control and Status Registers (CSR) Mapping x
4.4.2.1. Control and Status Register Field
4.5. Core Implementation x
4.5.1. Instruction Set Reference
1. Overview
2. Nios® V/c Processor
3. Nios® V/m Processor
4. Nios® V/g Processor
5. Nios V Processor Reference Manual Archives
6. Document Revision History for the Nios® V Processor Reference Manual

4.3.10.4.2. Accessing Tightly Coupled Memory

TCM occupies standard address space like other memory devices connected via system interconnect fabric. The processor configures the address ranges for TCM (if any).

Access from Processor Core

When TCM is present, the Nios® V/g processor core decodes addresses internally to determine if the requested addresses reside in the TCMs. If the address resides in the TCM, the processor core fetches the instruction from instruction TCM or loads the data from the data TCM. The software accesses TCM using regular load and store instructions. From the software’s perspective, there is no difference in accessing a TCM compared to other memory.

Accessing TCM bypasses cache memory. The processor core functions as if the cache were not present for the address span of the TCM. Instructions for managing the cache do not affect the TCM, even if the instruction specifies an address in TCM.

Access from External AXI4-Lite Manager

Any external AXI4-Lite manager can access any TCMs as RAM in the system if it is connected to the TCM’s AXI4-Lite interface. The TCMs support dual-port access, which allows two hosts (processor core and external AXI4-Lite manager) to access the memory simultaneously.

You can access the TCM memories of a Nios® V processor core (Core 1) from another core (Core 2) in a multi-core system. Core 2 acts as the external AXI4-Lite Manager in this setup. Enable this feature by connecting the data bus of Core 2 to the TCM AXI4-Lite subordinate port of Core 1.

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