f4pga VS skidl

I hope AMD sees the light and helps F4FPGA develop a more complete open source toolchain for their FGPAs (https://f4pga.org). With this subsystem and an open source compilation flow, FGPA experiments would be way easier.

I tried to get LiteX to work with F4PGA, an open source FPGA toolchain, instead of the Xilinx tools, but it was a huge hassle. Just use LiteX with the Xilinx tools.

Not really, at least not apples-apples for something like a Pi.

There are a couple of different aspects to this, one is that soft-logic it typically slower than hard-logic so you just can't get comparable frequencies out of a soft implementation. For datapath designs, this is typically solved by going wider, but that isn't quite as helpful or practical for all aspects of a processor implemented in soft logic.

If you look at the specs for this softcore processor, they have much less performance than a Pi, even when you're using some of the biggest and more $$ families of FPGAs: https://www.xilinx.com/products/design-tools/microblaze.html....

I'd say that is on-part with similar complexity soft-core CPUs from other vendors or even open-source ones.

With respect to the design transparency, it kind of depends on how much you care about the black-box compilers required to use a lot of these advanced chips. You can feed open-source RTL into them, but there's still a proprietary black-box compiler/fitter/place-route etc for a lot of these.

There's some work toward open toolchains from yosys and https://f4pga.org/, but none of the big FPGA companies seem very bought-in or willing to help a, so it's been a community best-effort, and for some of the fancier devices, you still have to use the proprietary tools to build bitstreams.

I am a believer that the open source days will come: https://f4pga.org/

Great question! We hope we have a few good reasons.

This iteration of the project actually came after first working with and then modifying another awesome project called SKiDL (https://github.com/devbisme/skidl).

It's based on Python - but we found that because since it's procedural, turing complete and has a rich eco-system - people use to that and there aren't standard composable ways of designing things. Instead of describing your board, you (practically) write a script that generates your board. It entangles your targets with your source-code and can make it difficult to understand the ultimate outcome of what you've written.

Additionally, since it's a potentially very long program, it was hard to write good language support around (a language server for VSCode, a schematic visualiser etc...) that were snappy, responsive and lent to examining modules as well as the whole program.

There's a few operators and first-class language features we wanted as well, like units and tolerances (3.3V +/- 100mV) that just aren't the same when embedded in a string, or class init method.

there is skidl for schematics, but yeah shit was hand drawn before GUIs.

Further, there are many python libraries etc which can be used to design electrical circuits using code: https://github.com/devbisme/skidl

I'd like to see documentation on your workflow. You can also post it on https://github.com/devbisme/skidl/discussions.

There is a generate_pcb() function in SKiDL that will output a kicad_pcb file that can be directly opened using PCBNEW (no need to generate the intermediate netlist file). That function uses HierPlace to group the parts based on their hierarchical organization. That would be a good place to inject some autoplacement if you get it figured out.

If others are interested in this and wireviz they might also like to know about https://github.com/devbisme/skidl. Used to make schematic specification in python.

Kinda off topic, but there's this project called skidl https://github.com/devbisme/skidl allowing you to create electrical schematics using Python. It seems to council your two interests, maybe for a fun side showoff project.

Take a look at this SKiDL discussion forums on GitHub: https://github.com/xesscorp/skidl/discussions/129

SKiDL (circuit design library) does this to a very large extent...

https://github.com/xesscorp/skidl