phison
serv
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phison
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Apple to Move a Part of Its Embedded Cores to RISC-V
Here's one with a 250MHz 8051: https://github.com/flowswitch/phison/wiki/PS2303
They don't need anything as powerful as ARM (and thus avoid the licensing fees), and it's a very price-sensitive market, so a fast 8051 + accelerator hardware is enough.
No doubt some of the more expensive ones may be ARM-based, but I think the 8051-based ones far outsell them in volume.
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
What are some alternatives?
picorv32 - PicoRV32 - A Size-Optimized RISC-V CPU
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.
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
riscv-cores-list - RISC-V Cores, SoC platforms and SoCs
IronOS - Open Source Soldering Iron firmware
fusesoc - Package manager and build abstraction tool for FPGA/ASIC development
neo430 - :computer: A damn small msp430-compatible customizable soft-core microcontroller-like processor system written in platform-independent VHDL.
psram-tang-nano-9k - An open source PSRAM/HyperRAM controller for Sipeed Tang Nano 9K / Gowin GW1NR-LV9QN88PC6/15 FPGA
edalize - An abstraction library for interfacing EDA tools
riscv_verilator_model - RISCV model for Verilator/FPGA targets
zipversa - A Versa Board implementation using the AutoFPGA/ZipCPU infrastructure
minimax - Minimax: a Compressed-First, Microcoded RISC-V CPU