FPGAwars: Exploring the Open Side of the FPGAs

https://fpgawars.github.io/

by MrXOR • 6 years ago

121 46 6 years ago

fpgawars.github.io

andy_ppp• 6 years ago

I really would love an open source, hackable FPGA DAC like the Chord DACs. What would be needed in addition to these cool looking boards for that to happen, I guess to code is pretty complicated for the USB interface to make it appear as a sound output ideally without drivers. Some kind of accurate clock and an output stage? Not sure if actually converting PCM to voltages over time is really that complicated...

IshKebab2• 6 years ago

That's definitely possible. The actual DAC but it's trivial - the hard but is that you would need to implement the USB Audio device class and a USB stack. That's a hell of a lot of code. Also what would be the point?

Kliment2• 6 years ago

Luckily there are wonderful USB stacks implemented in open FPGA toolchains these days - check out the toolchains described at https://workshop.fomu.im/en/latest/

ranma42• 6 years ago

USB Audio device class and a USB stack. That's a hell of a lot of code.

Its actually not that much for the bare minimum needed, though the USB docs are pretty daunting.

If you go with USB1, you basically just need enough to answer the descriptor and set interface queries and set up the endpoints (in particular the isochronous endpoint for audio is a bit more complex). If you stick to exactly one supported format and sample rate and don't include any control units, you can basically skip all the audio class control messages.

For USB1, in a pinch, you can use a cheap generic 24MHz usb logic analyzer and pulseview to decode the raw usb protocol for debugging (though with 24MHz you get some corruption in the capture from clock drift, you need at least 48MHz for more reliable signal sampling).

I'd guess you can make do with ~1k LOC in this case.

pjc503• 6 years ago

Not sure if actually converting PCM to voltages over time is really that complicated...

As someone working in this area, the USB interface is the boring standard bit and the actual analogue bit is both difficult and determines quality.

For what purpose do you want an open source DAC? Would you be happy with a chip doing USB to I2S for you and then doing the DAC yourself?

jjoonathan• 6 years ago

As someone skilled in the RF space but not the audiophile space -- why are audio DACs still a focus for innovation? The bandwidth, linearity, isolation, and jitter requirements all seem quite modest and distant from the edges of what's possible along every performance axis. Is it linearity at high power that's still a problem? With feedback techniques available, I wouldn't think so, but I could certainly be missing something. What's the sticking point?

Or is this more of a marketing game of adding hiss / distortion / lowpass / other non-idealities that perceptually improve quality and convincing people to use your DAC to do it rather than software? It seems a bit unlikely.

If I had to guess, it would be that the narrowly defined task of a DAC has been thoroughly solved and commodified while the high end of the space differentiates itself with industrially relevant features like failover, monitoring, durability, and compatibility. But then why the interest in a DIY DAC? Maybe I'm reading too much into this, it's all curiosity driven, and I shouldn't interpret a desire for DIY DACs as a statement that audio DACs aren't a solved problem.

Rochus2• 6 years ago

If you prefer a Verilog IDE instead of Icestudio's drawing approach, have a look at https://github.com/rochus-keller/verilogcreator/

swiley• 6 years ago

There's also the "icestorm" tools if you prefer a few minimal programs and a Makefile (which is very different from most commercial FPGA dev environments.)

Rochus2• 6 years ago

You need Icestorm or Symbiflow in any case; VerilogCreater doesn't include them.

captainmuon• 6 years ago

Side note: All text on that page is invisible if your browser language is not English or Spanish. I had to click "EN" at the very bottom to read anything.

severino3• 6 years ago

Well, nothing really surprising coming from Spaniards. There, three out of the four official languages are invisible too. Only the Spanish (Castilian) language is not.

harperlee4• 6 years ago

Cooficial languages are recognized in the Constitution. Every official website in the country is in the four languages. Public education is delivered in the local language without exception. Politics is done in the local language. Justice also. All public signs are in both spanish and the local language everywhere. Local versions of names (eg Sanxenxo instead of spanish San Genjo, Girona instead of Gerona) are always used in TV even when speaking in spanish. You get fined if your restaurant menu is only in spanish, at least in Catalonia.

Honest question: what else do you need? To be able to speak solely in basque when in Murcia?

AlbertoGP• 6 years ago

I just sent them a PR to fix that, and it’s merged: https://github.com/FPGAwars/fpgawars.github.io/issues/5

If either EN or ES is in your browser’s list of acceptable languages, the first one found will be used. If that list does not contain any of those, the default is ES.

intricatedetail2• 6 years ago

I love playing with FPGA. You can get an open cpu like picorv32, add your own instructions, peripherals, tweak the toolchain and you have your own custom stack down to your own cpu instructions. Then you can invoke these from your C program to achieve super fast data processing.

malux85• 6 years ago

What’s the best consumer level FPGA that I can buy to experiment with? One that has the highest speed of final product and most memory etc? What’s the best of the best?

jng• 6 years ago

Xilinx leads the pack (now part of AMD). There are boards based on their MPSoC family at very good prices (Ultra96 for around $250, only real thing that's missing is Ethernet but it has WiFi). Embedded ARM cores and ultrascale+ fabric. Very hard to beat.

Zynq 7000 family is a more affordable entry point, but resources are more limited in every regard, and uses a slower, more power consuming process.

Lattice-based boards are great because they are supported by open source tooling, and available in many indie buildouts (ECP5 or or ice). They are not so high end though, by far, compared to Xilinx parts.

Intel (ex-Altera) seems to have good stuff, but not as advanced as Xilinx. They are used on the mist and mister systems for hardware retro game emulation, a quite active scene.

sneak• 6 years ago

The answer depends on how much you want to hate your tooling. The fastest stuff uses all proprietary, heavily licensed/restricted tooling.

I like the lattice stuff for experimenting because you can do the whole stack with free software.

bmitc• 6 years ago

I am not really sure what you’re asking. You could get a Xilinx RFSoC, but the development board is like $10,000.

If you’re just wanting to learn and experiment, like myself, then Digilent makes a lot of nicely packaged boards. The Nexys A7 is a capable board.

Teknoman117• 6 years ago

My two gotos have been the Mojo v3 (Spartan 6 LX9) (fairly old at this point), they can be had for $30 on eBay and have a built in programmer, and the Alchitry Au (Artix 7 35T). It's $100, but it's nice and compact and has a ton of gates. Also has a built in programmer and 256 MiB of DDR3.

Neither of these have high speed serial interfaces (for things like ethernet, PCIe, HDMI, etc.), but they're fun starting points.

I'd love to get into making my own FPGA boards, but man, BGAs are scary from a hobbyist perspective. The Spartan 6 LX9 is neat (from a hobbyist perspective) in that it's a big QFP.

intricatedetail2• 6 years ago

You can try TinyFPGA. It has a fully open source toolchain and a lot of examples on Github. It is also quite inexpensive.

flatiron• 6 years ago

I have a MiSTER. One day I’ll figure out how to play with it (more than games) haven’t done fpga since college though.

0xcde4c3db• 6 years ago

In case you haven't been actively following development, there's now a "template" repository with the framework and a minimal core, so you don't have to figure out which ZX Spectrum bits to hack out:

https://github.com/MiSTer-devel/Template_MiSTer

mraza007• 6 years ago

I’m just curious to know how FPGAs are used in our industry

pjc503• 6 years ago

We have some for chip pre-production: testing the software before the hardware design is complete and comes back from the factory.

harperlee4• 6 years ago

Very happy to recognize on the HN frontpage work from an old professor of mine! Keep it up Obijuan, it would be great if more university teachers had your energy!

IfOnlyYouKnew• 6 years ago

Wait.. you had a professor named Obi-wan?

harperlee4• 6 years ago

His name is Juan, he goes by Obijuan in his open source contributions.

https://es.m.wikipedia.org/wiki/Juan_Gonz%C3%A1lez_G%C3%B3me...

FPGAwars: Exploring the Open Side of the FPGAs

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