S5 series
S51
The SiFive S51 Standard Core is a 64-bit embedded processor, fully compliant with the RISC-V ISA. A small-footprint, low-power design makes the S51 ideal for devices that require a tiny system controller in a larger 64-bit SoC. The S51 can also be used as a standalone controller for networking, storage, or other high-performance embedded applications

S51
Key Features
- Fully compliant with the RISC-V ISA specification
- RV64IMAC Support
- RV64I – 64-bit RISC-V with 32 integer registers
- Integer Multiplication and Division (M) support
- Atomic Mode (A) support for high-performance, portable software
- Compressed Mode (C) support for better code density
- Machine and User Mode Support
- In-order, 5-6 stage variable pipeline
- Advanced Memory Subsystem
- 16KB, 2-way Instruction Cache
- Instruction Tightly Integrated Memory (ITIM) option
- Up to 64KB Data Tightly Integrated Memory (DTIM) support
- Support for up to 40 physical address bits
- Efficient and Flexible Interrupts
- Local interrupts w/ vectored addresses — up to 16
- Platform Level Interrupt Controller (PLIC) — 511 interrupts w/ 7 priority levels
- RISC-V Core Local Interruptor (CLINT) — 1 timer, 1 SW
- 8-Region Physical Memory Protection (PMP)
- High performance AMBA Interfaces
- 2.87/1.74 DMIPS/MHz (Best Effort/Legal)
- 3.16 CoreMark/MHz
- Detailed Power, Performance, and Area (PPA) Information
S5 Series
Cortex-R5
Architecture
64-bit
32-bit
Cores
Up to 8 Cores
(fully-coherent)
(fully-coherent)
Up to 2 Cores
(non-coherent)
(non-coherent)
Interrupt Controller
Included; pre-integrated
Licensed separately; requires integration
L2 Cache Controller
Included (optional); pre-integrated
Licensed separately; requires integration
S51
Development Kit
Dev Kit Deliverables
- RTL Evaluation
- Test Bench RTL
- Software Development Kit
- FPGA Bitstream
- Documentation
S5
Series Overview
S5 Series
The S5 Series offers 64‑bit RISC‑V performance with 32‑bit power and area. The S5 core has a 5-6 stage pipeline, offering a great balance between performance and efficiency.
S5 Series
Highlights
Key Features
- Up to 8 coherent S5 Cores and optional L2 Cache Controller
- Configurable core performance
- Double precision Floating Point Unit
- Level 1 Memory System and ECC
- Physical addressing up to 47-bits
- Number, type, and width of bus interfaces
- Support for SiFive Insight Advanced Trace and Debug
Applications
- Consumer Electronics
- Motor Control
- Industrial Automation
- Storage
- High-performance embedded
Core Evaluation
From idea
to reality.
Ready to see your code in action? The S51 Development Kit enables free evaluation of SiFive RISC-V Core IP.
Key
Deliverables
Evaluation RTL
- Full-Functional, synthesizable Verilog RTL
- Run it in your own simulator
- Simple, no-cost evaluation license
Start S51 Free Trial
FPGA Bitstream
- Fully-functional SiFive RISC-V Core Complex with system peripherals
- High Performance - 32.5 MHz emulation
- Upload your own programs using the Freedom E SDK
Compatible with the Arty A7-100T FPGA and Xilinx VCU118 Development Boards: