serv
picorv32
serv | picorv32 | |
---|---|---|
20 | 16 | |
1,254 | 2,783 | |
- | 2.0% | |
7.6 | 5.2 | |
24 days ago | about 1 month ago | |
Verilog | Verilog | |
ISC License | ISC License |
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serv
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RISC-V support in Android just got a big setback
> Right now, most devices on the market do not support the C extension
This is not true and easily verifiable.
The C extension is defacto required, the only cores that don't support it are special purpose soft cores.
C extension in the smallest IP available core https://github.com/olofk/serv?tab=readme-ov-file
Supports M and C extensions https://github.com/YosysHQ/picorv32
Another sized optimized core with C extension support https://github.com/lowrisc/ibex
C extension in the 10 cent microcontroller https://www.wch-ic.com/products/CH32V003.html
This one should get your goat, it implements as much as it can using only compressed instructions https://github.com/gsmecher/minimax
- SERV – The SErial RISC-V CPU
- SERV: A bit-serial RISC-V core
- SERV – open-source Tiny SErial RISC-V CPU
- How many LUT for an 8 bit CPU?
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Minimax: a Compressed-First, Microcoded RISC-V CPU
In short: it works, though the implementation lacks the crystal clarity of FemtoRV32 and PicoRV32. The core is larger than SERV but has higher IPC and (very arguably) a more conventional implementation. The compressed instruction set is easier to expand into regular RV32I instructions than it is to execute directly.
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Apple to Move a Part of Its Embedded Cores to RISC-V
https://github.com/olofk/serv
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I have created a Reddit community about PicoBlaze soft processor...
As for the size advantage: this mattered more when LUTs were precious and when PicoBlaze's competition was either similarly unorthodox (J1 Forth CPU) or several times larger (MicroBlaze). Nowadays, there are very small RISC-V cores like FemtoRV32 Quark or SERV. RISC-V benefits from mainstream open-source tooling and has momentum that's hard to beat.
- Microchip to develop 12-core RISC-V processor for NASA
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RISC-V announces first new specifications of 2022 adding to 16 ratified in 2021
The RISC-V spec does allow non-trapping behavior and SeRV in particular has non-trapping behavior, which is an important part of how it can fit into 200 4-input LUTs.
https://github.com/olofk/serv#good-to-know
picorv32
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RISC-V support in Android just got a big setback
> Right now, most devices on the market do not support the C extension
This is not true and easily verifiable.
The C extension is defacto required, the only cores that don't support it are special purpose soft cores.
C extension in the smallest IP available core https://github.com/olofk/serv?tab=readme-ov-file
Supports M and C extensions https://github.com/YosysHQ/picorv32
Another sized optimized core with C extension support https://github.com/lowrisc/ibex
C extension in the 10 cent microcontroller https://www.wch-ic.com/products/CH32V003.html
This one should get your goat, it implements as much as it can using only compressed instructions https://github.com/gsmecher/minimax
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SPI PROTOCOL in FPGA
In contrast to most people here saying you NEED to spend money. I disagree with that. You can implement and simulate a SPI master/slave fully on your computer, no FPGA or other hardware required. There are simulation models for SPI peripherals you could use. For example: https://github.com/YosysHQ/picorv32/blob/master/picosoc/spiflash.v
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How many gates does a decent risc-v implementation take?
The Pico RV32 is pretty small, and can go as low as about 750 LUTs, with most features elided. I don't know how Xilinix LUTs translate to Lattice though.
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Open-source RISC-V CPU projects for contribution
Picorv32: https://github.com/YosysHQ/picorv32
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We ran a Unix-like OS (Xv6) on our home-built CPU with our home-built C compiler
There are loads of free RISC-V cores that you can read the source of and run on cheap FPGAs. Take a look at PicoRV32: https://github.com/YosysHQ/picorv32
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SUGGEST AN OPEN SOURCE RISC-V CORE DESIGNED IN VERILOG
picorv32 is written in Verilog.
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Minimax: a Compressed-First, Microcoded RISC-V CPU
In short: it works, though the implementation lacks the crystal clarity of FemtoRV32 and PicoRV32. The core is larger than SERV but has higher IPC and (very arguably) a more conventional implementation. The compressed instruction set is easier to expand into regular RV32I instructions than it is to execute directly.
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Apple to Move a Part of Its Embedded Cores to RISC-V
That is, reducing the number of LUT required to implement a CPU of a given ISA.
A basic RV32 CPU is down to 500-700 LUT.
https://github.com/YosysHQ/picorv32
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Designing a reasonable memory interface
I've bought a cheap FPGA board (Sipeed Tang Nano 9K) because I want to implement a little 8 or 16-bit CPU. The FPGA has plenty of BRAM for such a little CPU, so I wouldn't even need to implement an SPI controller initially, but I want to implement a von Neumann architecture, and was wondering if the only way of doing so using single port (or semi dual port) RAM would be to use 2 cycles or more for memory transfer operations (one for loading the instruction, one for executing the actual memory transfer), or if there was any technique that could be used to avoid this without having to implement instruction-level parallelism. Even if not, references to understandable code implementing a simple memory interface would be appreciated. I looked at PicoRV32 but couldn't really understand its inner workings.
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Risc-v rv32i softcore processor for Zybo-z7-10
Have you looked at PicoRV32? https://github.com/YosysHQ/picorv32
What are some alternatives?
neorv32 - :rocket: A tiny, customizable and extensible MCU-class 32-bit RISC-V soft-core CPU and microcontroller-like SoC written in platform-independent VHDL.
openlane - OpenLane is an automated RTL to GDSII flow based on several components including OpenROAD, Yosys, Magic, Netgen and custom methodology scripts for design exploration and optimization.
riscv-cores-list - RISC-V Cores, SoC platforms and SoCs
neorv32-setups - 📁 NEORV32 projects and exemplary setups for various FPGAs, boards and (open-source) toolchains.
IronOS - Open Source Soldering Iron firmware
rocket-chip - Rocket Chip Generator
fusesoc - Package manager and build abstraction tool for FPGA/ASIC development
skywater-pdk - Open source process design kit for usage with SkyWater Technology Foundry's 130nm node.
neo430 - :computer: A damn small msp430-compatible customizable soft-core microcontroller-like processor system written in platform-independent VHDL.
wd65c02 - Cycle accurate FPGA implementation of various 6502 CPU variants
psram-tang-nano-9k - An open source PSRAM/HyperRAM controller for Sipeed Tang Nano 9K / Gowin GW1NR-LV9QN88PC6/15 FPGA
Projects - Ted Fried's MicroCore Labs Projects which include microsequencer-based FPGA cores and emulators for the 8088, 8086, 8051, 6502, 68000, Z80, Risc-V, and also Typewriter and EPROM Emulator projects. MCL51, MCL64, MCL65, MCL65+, MCL68, MCL86, MCL86+, MCL86jr, MCLR5, MCLZ8