AndesCore™ D23

Compact, Secure and Performance Efficiency 32-bit RISC-V Core

AndesCore™ D23 Overview

  • AndeStar™ V5 Instruction Set Architecture (ISA)
  • Andes extensions for performance and code size enhancements
  • 3-stage pipeline optimized for gate count and efficiency 
  • 16/32-bit mixable instructions for code density 
  • Instruction and data caches to speed up accessing embedded or external flash memory 
  • Branch prediction to speed up control code 
  • Enhanced and Supervisor-mode Physical Memory Protection (ePMP and sPMP) to enhance core security
  • Core-Local Interrupt Controller (CLIC) for fast response, interrupt prioritization and pre-emption and Platform-Level Interrupt Controller (PLIC) for a wide range of cores and system event scenarios
  • Patented CoDense™ technology to compress program code on top of the 16-bit extension 
  • Instruction Trace Interface supports RISC-V Processor Trace v1.0
  • StakeSafe™ hardware to measure stack size, and detect runtime overflow/underflow
  • Programmable Physical Memory Attributes (PPMA) for setting memory attributes dynamically 
  • PowerBrake, WFI/WFE (Wait For Interrupt/Event) for power management on different occassions

AndesCore™ D23 is a 32-bit 3-stage pipeline CPU IP core based on AndeStar™ V5 architecture for embedded applications with small gate count, and some dual-issue ability. In addition to commonly used RISC-V I/EMAC, single/double precision FPU and DSP extensions, it supports the recently ratified ISA extensions such as B (bit manipulation), K (scalar cryptography), and CMO (cache management operations) as well as Zce draft (code size reduction).  The D23 implements ePMP and sPMP to improve core security; PPMA for on-the-fly change of memory attributes; and Andes V5 extensions that include StackSafe™ (for hardware stack protection), CoDense™, PowerBrake and WFI/WFE.  The D23 supports both four-wire and two-wire JTAG debug and instruction trace interface for software development.  On the performance front, it deploys several configurable options such as dynamic branch prediction, caches and local memories, multiplier optimized for performance or area.  Moreover, it comes with rich features to ease SoC integration such as CLIC and PLIC for interrupt handling; an AHB-Lite system bus and an AHB-Lite low-latency interface; an APB bus for CPU local peripherals, and an AHB-Lite local memory access port for external bus masters.  Some of the features will be implemented in CPU revision update, details below.  

Applications

  • Sensor fusion
  • Smart Home and Matter (standard)
  • Small IoT devices
  • Wearable devices
  • Motor control 

Block Diagram

Development Tools

  • AndeSight™ Integrated Development Environment (Eclipse-based)
  • AndeShape™ FPGA Development Boards
  • COPILOT: Automation tool for Andes Custom Extension™ (ACE)
  • Debugging Hardware

Key Features and Performance

AndeStar™ V5 (RV32I) 32-bit Architecture

Key FeaturesBenefits
  • RISC-V RV32 I, M, A, B, C, P* instructions
  • F, D, K, CMO, Zce instructions planned in revision update
    • State-of-the art ISA from latest developments in computer architecture
    • Industry standard and open architecture
    Andes Extended InstructionsAndes exclusive performance and functionality enhancements
    16/32-bit mixable instruction formatFor compact code density
    32 general-purpose registersFor better code size or performance
  • Machine (M), optional User (U) Privilege levels
  • Optional Supervisor (S) Privilege level planned in revision update
    		• Embedded systems with privilege protections

    *P-extension is in draft

    CPU Core

    Key FeaturesBenefits
    2.0 DMIPS/MHz, 4.5 CoreMark/MHzSuperior performance-per-MHz
    3-stage pipelineOptimized for gate count and efficiency
    Static or dynamic branch predicationSpeed up branch control codes
  • Enhanced Physical Memory Protection (ePMP), up to 32 entries
  • Supervisor mode PMP (sPMP), up to 32 entries, planned in revision update
    		• Enhance core security
    Programmable Physical Memory Attributes (PPMA), up to 8 regionsBasic read/write/execute memory protection with minimum cost
    Performance monitorsPerformance tuning
    StackSafe™ hardware stack protection, planned in revision update
    • Easy identification of stack size threshold during development
    • Hardware error detection of stack overflow and underflow at runtime

    Multiplier options:

    • Pipelined with 2-cycle latency, or
    • Sequential with 1/2/4/8-bit results per cycle
    		Option to choose between speed and area according to application's requirements

    Power Management

    • PowerBrake technology, planned in revision update
    • WFI(Wait for Interrupt) and WFE(Wait for Event)
    		Performance throttling to digitally reduce power consumption WFI instruction and WFE CSR for software power control

    Memory Subsystems

    Key FeaturesBenefits

    Unified read-only instruction cache, or Instruction and Data Caches

    • Configurable from 1KB up to 32KB
    • Parity for I$; ECC for I$/D$
    • Accelerating accesses to slow memories
    • Flexible cache configurations

    I/D Local Memory

    • Size: Individually configurable from 1KB up to 512MB with ECC protection
    • SRAM or AHB-Lite interface support
    • For deterministic and efficient program execution
    • Flexible size selection to fit diversified needs

    Bus interfaces

    Key FeaturesBenefits
    • 32-bit AHB-L System Port - synchronous N:1 core-to-bus clock ratio
    • 32-bit AHB-L Low Latency Port
    • 32-bit APB Peripheral Port
    • 32-bit AHB-L Local Memory Access Port
    • System Port with synchronous N:1 core-to-bus clock ratio to provide user-selectable bus interface for optimal efficiency and ease SoC integration
    • Low Latency Port for latency-sensitive peripherals
    • APB interface for private peripherals
    • Local Memory Access Port allows external bus master to access local memory

    Core-Local Interrupt Controller (CLIC)

    Key FeaturesBenefits
    Up to 1002 interrupt sources, and up to 255 interrupt priority levelsAllow core local interrupts to be serviced and prioritized without sharing

    Enhanced interrupt features

    • Selective vectoring with priority preemption
    • Support for software-based tail chaining
    • Faster interrupt handling for real-time applications
    • Complete hardware preemption support for faster response
    • Flexible interrupt source interface for simpler SoC design

    Platform-Level Interrupt Controller (PLIC)

    Key FeaturesBenefits

    Implements RISC-V PLIC specification

    • Up to 1023 interrupt sources
    • Up to 255 interrupt priority levels
    		Interrupt handling for SoC with multiple processors

    Enhanced interrupt features

    • Priority-based preemption
    • Selectable edge trigger or level trigger
    		Complete hardware preemption support

    Debug Support

    Key FeaturesBenefits
    Implements RISC-V debug specificationsSupported by industry debug tool suppliers
    2-wire serial or 4-wire JTAGIndustry-standard support
    Embedded Debug Module with 2/4/8 triggersFlexible configurations to tradeoff between gate count and debugging capabilities
    Optional password-based secure debugEnhanced secure debugging

    Trace Support

    Key FeaturesBenefits
    RISC-V Processor Trace v1.0 supportSupport instruction trace according to RISC-V standard

    Standard Product Package

    AndesCore™ D23 with AE350 Platform CPU Subsystem

    • Pre-integrated D23, PLIC, shared debug system, and AHB AE350 Platform

    Press Release