7 ms·

FPGAwars: Exploring the Open Side of the FPGAs

121 points by MrXOR 6y ago

andy_ppp 6y 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...
- IshKebab 6y 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?
  - Kliment 6y 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/ https://workshop.fomu.im/en/latest/
    - IshKebab 6y ago
      I wondered if there might be, but did you post the right link? I can't see anything about open source USB device implementations there.
      - ohazi 6y ago
        Kate Temkin's Luna project is super cool, although I think it's still a WIP: https://github.com/greatscottgadgets/luna https://github.com/greatscottgadgets/luna It's a USB stack implemented as pure gateware - no hard/soft CPU needed, although I think you can hook one up if you want to.
      - Kliment 6y ago
        The code linked there is all open, and has a USB device softcore. It's the most approachable FPGA USB implementation I've played with. edit: Here is the actual USB core that's in there: https://github.com/im-tomu/valentyusb/ https://github.com/im-tomu/valentyusb/
  - ranma42 6y 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.
- pjc50 6y 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 6y 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.
    - nsb1 6y ago
      I would love to know the answer to this for all the same reasons. Is there some actual special sauce or is the world of 'audiophile DACs' just the new 'Monster Cable' FUD?
      - auxym 6y ago
        I don't think there's any special sauce, at least nothing that justifies stupidly high audiophile pricing. ESS "sabre32" DAC ICs are widely regarded as excellent and even integrated into high end audio products, yet they can be bought in small quantities for 12$ each: http://www.shawelectronics.com/es9018k2m.html http://www.shawelectronics.com/es9018k2m.html
Rochus 6y ago
If you prefer a Verilog IDE instead of Icestudio's drawing approach, have a look at https://github.com/rochus-keller/verilogcreator/ https://github.com/rochus-keller/verilogcreator/
- swiley 6y 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.)
  - Rochus 6y ago
    You need Icestorm or Symbiflow in any case; VerilogCreater doesn't include them.
captainmuon 6y 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.
- severino 6y 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.
  - deleted 6y ago
    [deleted]
  - harperlee 6y 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?
    - severino 6y ago
      > Every official website in the country is in the four languages This is plain wrong. I could give you (just making a quick Google search) hundreds of examples where you can see it's not true. Co-official languages are just second-class citizens here. Not only dozens of official web sites are Spanish language only, but also those who offer language selection mostly just change the menu option titles, but the actual content is only in Spanish. Even Spain's anti-covid mobile application (Radar Covid) -whose UI is just a couple of messages, nothing very hard to translate- got translated to all the official languages only recently. https://portal.mineco.gob.es/gl-es/comunicacion/Paxinas/default.aspx https://portal.mineco.gob.es/gl-es/comunicacion/Paxinas/defa... (I chose "GL", but the news are still in "ES") https://www.casareal.es/GL/Paginas/home.aspx https://www.casareal.es/GL/Paginas/home.aspx (the same) https://industria.gob.es/renove/paginas/index.aspx https://industria.gob.es/renove/paginas/index.aspx (where's my language menu?) https://www.rtve.es/ https://www.rtve.es/ (no languages for our public televison website?) This last one is a good example, because everybody, regardless of his language, funds RTVE through taxes, yet its live contents are mostly Spanish language only. And we can find similar examples for the other topics. But no, I don't care what they do or speak in Murcia, I just want to have the same rights that someone from Murcia has in my region.
intricatedetail 6y 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 6y 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 6y 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.
  - Teknoman117 6y 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.
  - sneak 6y ago
flatiron 6y 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 6y 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 https://github.com/MiSTer-devel/Template_MiSTer
mraza007 6y ago
I’m just curious to know how FPGAs are used in our industry
- pjc50 6y ago
  We have some for chip pre-production: testing the software before the hardware design is complete and comes back from the factory.
harperlee 6y 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 6y ago
  Wait.. you had a professor named Obi-wan?
  - harperlee 6y 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%B3mez https://es.m.wikipedia.org/wiki/Juan_Gonz%C3%A1lez_G%C3%B3me...

121 points by MrXOR 6y 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...

IshKebab 6y 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?
- Kliment 6y 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/ https://workshop.fomu.im/en/latest/
  - IshKebab 6y ago
    I wondered if there might be, but did you post the right link? I can't see anything about open source USB device implementations there.
    - ohazi 6y ago
      Kate Temkin's Luna project is super cool, although I think it's still a WIP: https://github.com/greatscottgadgets/luna https://github.com/greatscottgadgets/luna It's a USB stack implemented as pure gateware - no hard/soft CPU needed, although I think you can hook one up if you want to.
    - Kliment 6y ago
      The code linked there is all open, and has a USB device softcore. It's the most approachable FPGA USB implementation I've played with. edit: Here is the actual USB core that's in there: https://github.com/im-tomu/valentyusb/ https://github.com/im-tomu/valentyusb/
- ranma42 6y 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.
pjc50 6y 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 6y 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.
  - nsb1 6y ago
    I would love to know the answer to this for all the same reasons. Is there some actual special sauce or is the world of 'audiophile DACs' just the new 'Monster Cable' FUD?
    - auxym 6y ago
      I don't think there's any special sauce, at least nothing that justifies stupidly high audiophile pricing. ESS "sabre32" DAC ICs are widely regarded as excellent and even integrated into high end audio products, yet they can be bought in small quantities for 12$ each: http://www.shawelectronics.com/es9018k2m.html http://www.shawelectronics.com/es9018k2m.html

Rochus 6y ago

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

swiley 6y 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.)
- Rochus 6y ago
  You need Icestorm or Symbiflow in any case; VerilogCreater doesn't include them.

captainmuon 6y 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.

severino 6y 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.
- deleted 6y ago
  [deleted]
- harperlee 6y 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?
  - severino 6y ago
    > Every official website in the country is in the four languages This is plain wrong. I could give you (just making a quick Google search) hundreds of examples where you can see it's not true. Co-official languages are just second-class citizens here. Not only dozens of official web sites are Spanish language only, but also those who offer language selection mostly just change the menu option titles, but the actual content is only in Spanish. Even Spain's anti-covid mobile application (Radar Covid) -whose UI is just a couple of messages, nothing very hard to translate- got translated to all the official languages only recently. https://portal.mineco.gob.es/gl-es/comunicacion/Paxinas/default.aspx https://portal.mineco.gob.es/gl-es/comunicacion/Paxinas/defa... (I chose "GL", but the news are still in "ES") https://www.casareal.es/GL/Paginas/home.aspx https://www.casareal.es/GL/Paginas/home.aspx (the same) https://industria.gob.es/renove/paginas/index.aspx https://industria.gob.es/renove/paginas/index.aspx (where's my language menu?) https://www.rtve.es/ https://www.rtve.es/ (no languages for our public televison website?) This last one is a good example, because everybody, regardless of his language, funds RTVE through taxes, yet its live contents are mostly Spanish language only. And we can find similar examples for the other topics. But no, I don't care what they do or speak in Murcia, I just want to have the same rights that someone from Murcia has in my region.

intricatedetail 6y 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 6y 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 6y 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.
- Teknoman117 6y 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.
- sneak 6y ago

flatiron 6y 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 6y 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 https://github.com/MiSTer-devel/Template_MiSTer

mraza007 6y ago

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

pjc50 6y ago
We have some for chip pre-production: testing the software before the hardware design is complete and comes back from the factory.

harperlee 6y 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 6y ago
Wait.. you had a professor named Obi-wan?
- harperlee 6y 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%B3mez https://es.m.wikipedia.org/wiki/Juan_Gonz%C3%A1lez_G%C3%B3me...