Ask HN: Where do I get started on ASICs, FPGA, RTL, Verilog et. al? • Hacker News Board

Re: Ask HN: Where do I get started on ASICs, FPGA, RTL, Verilog et. al?

#31

Post by j_s » Sun, Oct 01, 2017, 9:26 PM UTC

Here's my collection of discussions with recommendations that I've saved just in case I decide to take a single step in this direction someday:

Open Source Needs FPGAs; FPGAs Need an On-Ramp | https://news.ycombinator.com/item?id=14008444 (Apr 2017)

GRVI Phalanx joins The Kilocore Club | https://news.ycombinator.com/item?id=13448166 (Jan 2017)

What It Takes to Build True FPGA as a Service | https://news.ycombinator.com/item?id=13153893 (Dec 2016)

Low-Power $5 FPGA Module | https://news.ycombinator.com/item?id=9863475 (Jul 2015)

Re: Ask HN: Where do I get started on ASICs, FPGA, RTL, Verilog et. al?

#32

Post by exikyut » Sun, Oct 01, 2017, 9:45 PM UTC

I've gotten curious about FPGAs myself of late, particularly with video capture. A hopefully-on-topic question of my own, if I may:

I've seen that some FPGA boards have HDMI transceivers that will decode TMDS and get the frame data into the FPGA somehow. That got me thinking about various possibilities.

- I want to build a video capture device that will a) accept a number of TMDS (HDMI, DVI, DisplayPort) and VGA signals (say, 8 or 10 or so inputs, 4-5 of each), simultaneously decode all of them to their own framebuffers, and then let me pick the framebuffer to show on a single HDMI output. This would let me build a video switcher that could flip between channels with a) no delay and b) no annoying resyncs and c) because everything's on independent framebuffers I can compensate for resolution differences (eg, a 1280x1024 input on the 1920x1080 output) via eg centering.

- In addition to the above, I also want to build something that can actually _capture_ from the inputs. It's kind of obvious that the only way to be able to do this is via recording to a circular window in some onboard DDR3 or DDR4 (256GB would hold 76 seconds of 4K @ 144fps). My problem is actually _dumping_/saving the data in a fast way so I can capture more input.

I can see two ways to build this

1) a dedicated FPGA board with onboard DDR3, a bunch of SATA controllers and something that implements the equivalent of RAID striping so I can parallelize my disk writes across 5 or 10 SSDs and dump fast enough.

2) A series of FPGA cards, each which handles say 2 or 3 inputs, and which uses PCI bus mastering to write directly into a host system's RAM. That solves the storage problem, and would probably simplify each card. I'd need a fairly beefy base system, though; 4K 144fps is 26GB/s, which is uncomfortably close to PCI-e 3.0 x16's limit of 32GB/s.

I'll admit that this mostly falls under "would be really really awesome to have"; I don't have a commercial purpose for this yet, just to clarify that. That said, my inspiration is capturing pixel-perfect, perfectly-timed output from video cards to identify display and rendering glitches (particularly chronologically-bound stuff, like dropped frames) in software design, so there's probably a market for something like this in UX research somewhere...

Re: Ask HN: Where do I get started on ASICs, FPGA, RTL, Verilog et. al?

#33

Post by carussell » Sun, Oct 01, 2017, 9:45 PM UTC

jsolson wrote: post #15

kregasaurusrex wrote: post #7

Earlier quoted context omitted.

What's the best way for a novice to determine what their needs are? One thing that's been a barrier to entry for me has been fear of vendor lock-in from point of sale with regards to upgrading in the future; ie: purchasing a starter kit by company X but once determining that only company Y supports the feature set. Where there would then require a non-trivial amount devtime would be sunk in re-tooling your code both…

There are basically two companies in this business, Altera (Intel) and Xilinx. I would not worry about vendor lock-in for now -- there are some quite affordable dev boards (like the Arty ( http://store.digilentinc.com/arty-a7-artix-7-fpga-developmen... ) I've mentioned elsewhere), and no matter what you pick there's a ton of tooling. The concepts from the tools will translate between vendors, though, even if the comm…

To add to this:

Xcell is the name of Xilinx's self-published journal(s), and it's free. Here's the Xcell portal:

http://www.xilinx.com/about/xcell-publications.html

Here's a short article published in Xcell by Niklaus Wirth after he designed and prototyped a RISC CPU on a Xilinx FPGA:

https://issuu.com/xcelljournal/docs/xcell_journal_issue_91/3...

And finally, it's worth noting that the most recent post on the Xcell blog is one titled "Found! A great introduction to FPGAs", which was written just a couple days ago and is a glowing recommendation for the textbook "Digital System Design with FPGA: Implementation Using Verilog and VHDL".

https://forums.xilinx.com/t5/Xcell-Daily-Blog/Found-A-great-...

Re: Ask HN: Where do I get started on ASICs, FPGA, RTL, Verilog et. al?

#34

Post by pjc50 » Sun, Oct 01, 2017, 9:46 PM UTC

exikyut wrote: post #25

jleahy wrote: post #16

Earlier quoted context omitted.

You can actually get an ASIC manufactured for a few thousand dollars via CMP or Europractice. So not quite Google money. The difficulty is in paying for the software licenses you need to go from Verilog to DRC checked GDSII files (which is what you need to send to them). In fact personally I think this is a much better route for open source hardware. Reverse engineering FPGA bitstreams impressive, but you're swimming…

I'm very interested in this. I read that one small design (which I knew was very small, but not quantitatively so) cost approximately $5k per small run. How is the cost calculated? I presume size of final wafer (ie, number of chips produced) at least; does transistor count per chip influence anything too? Finally, is it possible to produce and maintain a fully open-source design that's the chip-fab equivalent of the…

The equivalent term is "GDSII", and I think it is possible, but I'm not aware of an example. Definitely not for beginners.

"Full open source" encounters some odd corner cases in EDA because it's not software. Eg Do you use the foundry's library for things like IO pads?

Re: Ask HN: Where do I get started on ASICs, FPGA, RTL, Verilog et. al?

#35

Post by sandGorgon » Sun, Oct 01, 2017, 9:53 PM UTC

Its quite late here, so I'll be brief. You mentioned the words "how IP is managed in chip industry" - so I'm going to move past the bookish knowledge and the tutorials and the open source code.

The chip design and EDA industry are very closeted and niche - there is so much knowledge there that is not part of any manual.

For example for a newcomer, you wouldn't even know what testing and validation in chip design would be - or how formal verification is an essential part of testing.

You wouldn't know what synthesis is, what is place and route, and GDS masks for foundries.

There is seriously no place to learn this. The web design or the AI world works very different - you can be a very productive engineer through Udacity. Not with ASIC.

You need to find a job in the chip design or EDA industry. There is seriously no other way.

If I had to make a wild parallel - the only other industry that works like this are people who make compilers for a living. Same technology, same problems, similar testing steps I guess.

Re: Ask HN: Where do I get started on ASICs, FPGA, RTL, Verilog et. al?

#36

Post by [deleted] » Sun, Oct 01, 2017, 9:57 PM UTC

[deleted]

Re: Ask HN: Where do I get started on ASICs, FPGA, RTL, Verilog et. al?

#37

Post by lvoudour » Sun, Oct 01, 2017, 9:58 PM UTC

jsolson wrote: post #11

I'd start with learning a hardware description language and describing some hardware. Get started with Verilog itself. I'm a fan of the [Embedded Micro tutorials]( https://embeddedmicro.com/tutorials/mojo ) -- see the links under Verilog Tutorials on the left (they're also building their own HDL, which unless you own a Mojo board isn't likely of interest). Install Icarus Verilog and run through the tutorials making s…

I actually want to understand the chip manufacturing process - design, prototyping (using FPGAs, etc), baking process in foundries. And also at least a basic understanding of how IP is managed in chip industry - like "IP core" is a term that I frequently hear but due to the myriad interpretations available online, I don't really understand what an "IP core" really means. Hoping to get useful advice from veterans in the chip industry.

I was about to write a thorough answer but jsolson's very good answer mostly covered what I had to say. I'll add my 2 cents anyway

- To understand the manufacturing process you need to know the physics and manufacturing technology. That's very low level stuff that takes years to master. There are books and scientific papers on the subject but it's a game very few players can play (ie. big manufacturers like intel and TSMC, maybe top universities/research centres). You can try some introductory books like Introduction to Microelectronic Fabrication [1] and Digital Integrated Circuits [2] by Rabaey if you're curious

- You can design ASICs without being an "expert" on the low level stuff, but the tools are very expensive (unless you're a student and your college has access to those tools). You need to learn VHDL/Verilog, definitely need the right tools (which, I'll say it again, are too expensive for hobbyists) and extra money to spend for manufacturing.

- FPGAs are different. No need to know the physics and you don't have to bother with expensive tools and foundries, the chip is already manufactured. My advice is to

(a) get an FPGA board. Digilent boards are a good choice as jsolson said, but there are other/cheaper solutions as well [3][4]. You'll still need software tools but (for these boards) they are free

(b) learn VHDL and/or Verilog. Plenty of books and online resources. A good book I recommend is RTL Hardware Design Using VHDL [5]

(c) I assume you know some basic principles of digital design (gates, logic maps, etc.). If not you'll need to learn that first. A book is the best option here, I highly recommend Digital Design [6] by Morris Mano

[1] https://www.amazon.com/Introduction-Microelectronic-Fabricat...

[2] https://www.amazon.com/Digital-Integrated-Circuits-2nd-Rabae...

[3] https://www.scarabhardware.com/minispartan6/

[4] http://saanlima.com/store/index.php?route=product/product&pa...

[5] http://eu.wiley.com/WileyCDA/WileyTitle/productCd-0471720925...

[6] https://www.amazon.com/Digital-Design-3rd-Morris-Mano/dp/013...

Re: Ask HN: Where do I get started on ASICs, FPGA, RTL, Verilog et. al?

#38

Post by pjc50 » Sun, Oct 01, 2017, 9:58 PM UTC

exikyut wrote: post #32

I've gotten curious about FPGAs myself of late, particularly with video capture. A hopefully-on-topic question of my own, if I may: I've seen that some FPGA boards have HDMI transceivers that will decode TMDS and get the frame data into the FPGA somehow. That got me thinking about various possibilities. - I want to build a video capture device that will a) accept a number of TMDS (HDMI, DVI, DisplayPort) and VGA sign…

The capture thing appears to exist: https://www.blackmagicdesign.com/products/hyperdeckshuttle/ - presumably it applies lossless compression. Lossless encoding within the h264 container should be possible.

Re: Ask HN: Where do I get started on ASICs, FPGA, RTL, Verilog et. al?

#39

Post by jleahy » Sun, Oct 01, 2017, 10:00 PM UTC

exikyut wrote: post #25

jleahy wrote: post #16

Earlier quoted context omitted.

You can actually get an ASIC manufactured for a few thousand dollars via CMP or Europractice. So not quite Google money. The difficulty is in paying for the software licenses you need to go from Verilog to DRC checked GDSII files (which is what you need to send to them). In fact personally I think this is a much better route for open source hardware. Reverse engineering FPGA bitstreams impressive, but you're swimming…

I'm very interested in this. I read that one small design (which I knew was very small, but not quantitatively so) cost approximately $5k per small run. How is the cost calculated? I presume size of final wafer (ie, number of chips produced) at least; does transistor count per chip influence anything too? Finally, is it possible to produce and maintain a fully open-source design that's the chip-fab equivalent of the…

The cost depends on the technology. More modern processes are dramatically more expensive (don't even think about something like 28nm). If you're looking at something ancient like 130nm, 0.35um, etc then it's going to be something like $1-2k per mm^2. Normally there's a minimum cost of a few mm^2. Expect to get a few tens of chips back. Transistor count has no effect, they couldn't care less what you put inside your part of the wafer, so long as it follows the design rules (for example minimum % coverage on each layer to prevent it collapsing vertically), but obviously if you need more transistors you might need more area.

Yes it's 100% possible to do an open-source design, qflow has been used to make sub-circuits of ASICs, but it's going to be extremely difficult. There are lots of things missing which you'd have to take from the fabs PDK or design yourself, for example open source I/O pads (sounds boring, but actually lots of work with ESD, etc). Combined with huge missing feature-sets in the open source tools, like extraction of designs back to SPICE circuits with parasitics and complete DRC checking, you're not going to have a fun time.

Re: Ask HN: Where do I get started on ASICs, FPGA, RTL, Verilog et. al?

#40

Post by j_s » Sun, Oct 01, 2017, 10:05 PM UTC

exikyut wrote: post #32

I've gotten curious about FPGAs myself of late, particularly with video capture. A hopefully-on-topic question of my own, if I may: I've seen that some FPGA boards have HDMI transceivers that will decode TMDS and get the frame data into the FPGA somehow. That got me thinking about various possibilities. - I want to build a video capture device that will a) accept a number of TMDS (HDMI, DVI, DisplayPort) and VGA sign…

Perhaps related, if not quite as ambitious:

https://hdmi2usb.tv/home/ - Open video capture hardware + firmware

I would also recommend this project if someone doesn't have an idea of their own, and/or doesn't have any fpga experience. So if someone is looking for people with both of those doing work in the open who might be willing to mentor them, finding a way to help this project is a great way to get started.