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Breaking The Three Laws
 
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    Breaking the Three Laws is dedicated to discussing technically challenging ASIC prototyping problems and sharing solutions.
  • About the Author

    Michael (Mick) Posner joined Synopsys in 1994 and is currently Director of Product Marketing for Synopsys' FPGA-Based Prototyping Solutions. Previously, he has held various product marketing, application consultant and technical marketing manager positions at Synopsys. He holds a Bachelor Degree in Electronic and Computer Engineering from the University of Brighton, England.

Archive for the 'Tips and Traps' Category

Automated Timing Biased Partitioning

Posted by Michael Posner on 20th March 2015

I spent a lot of time this week talking about timing biased automated partitioning which is the ability of the ProtoCompiler partition engine to generate a partition and pin multiplexing implementation with the goal of maximizing performance of the final prototype implementation. As it’s getting close to Easter I thought it was fitting to discuss ProtoCompiler’s Multi-Hop optimization algorithm. (Easter, Easter bunny, hop, you see what I did there?)

Firstly what is a Hop you ask? In the image below you can see the ASIC design example with combinatorial logic between two register points

ASIC Design with logic clouds between register points

It’s possible during partitioning for FPGA-based prototyping that these two registers end up in different FPGA’s as seen in the image below.

Example of a single "Hop" between FPGAs on a physical prototype

This is what is known as a single hop. The design has been split up with the starting and ending register points in separate FPGA’s. However, without timing biased capabilities it’s possible that a partition is created that spans multiple FPGA’s. An example of this Multi-Hop is represented in the image below

Example of what a multi-hop is

In our example above FPGA B has basically become a feed through FPGA and while this helps a partition engine get to a partition solution it has a dramatic effect on the overall performance of a prototype platform. To explain the timing impact lets go back to our original ASIC design and review the timing between the register points

Timing delay of this logic in ASIC implementation

In our made up example the combinatorial logic has a timing impact of about 10ns. However in our FPGA partition where you have the critical path split up over multiple FPGA’s timing becomes much more significant. The reason for this is that you typically have to apply pin multiplexing between FPGA’s as you have more signals than you have physical pins (One of the three ASIC Prototyping three laws which are the grounding facts driving this blog) Now if you review the timing impact with a typical pin multiplexing scheme inserted you suddenly see the impact of a Multi-Hop

Tming impact of multi-hops and pin multiplexing

But not to worry if you are using ProtoCompiler as the partition engine is not only fast but it’s timing biased and includes a Multi-Hop optimization algorithm.

When Multi-Hop optimization is enabled ProtoCompiler partition engine will:

  • Focus on reducing the number of multi-hops, with a goal of zero
  • If multi-hops are needed to complete the partition the focus turns to reducing the path length of the multi-hop
  • Avoids pin-multiplexing on multi-hop path
  • If pin-multiplexing is needed the focus turns to using the lowest pin-multiplexing ratio on the multi-hop path
  • Selects pin-multiplexing ratio based on timing slack

Knowing that eliminating multi-hops would lead to higher prototype performance you might think that by default the partition engine should not allow any multi-hops. However multi-hops do play a vital role sometimes in enabling an automated partition solution to be found.

ProtoCompiler’s timing biased multi-hop optimization is making a huge impact on the resulting HAPS prototyping performance. Across a suite of over 40 ASIC designs ProtoCompilers timing biased optimizations improved the clock period by an average of 50ns. HUGE improvement in resulting performance. Across this suite of designs, ProtoCompiler reduced the number of nets that are included in multi-hop paths of length two or greater by up to 80%. For most designs in the suite, the number of paths of length three or greater was reduced to ZERO. Also, for most designs in the suite, the pin multiplexing ratio of the multi-hop path nets required to get feasible automated partition was reduced to one (i.e. no pin-multiplexing required). Fantastic. Not only is ProtoCompiler’s partition engine super-fast running in minutes for multi-million ASIC gate design but the out of the box results are phenomenal.

I’m out on vacation for a week (yes even I need time off once in a while) so no blog next week.

Posted in ASIC Verification, FPGA-Based Prototyping, Tips and Traps | Comments Off

Want it all? Capacity, TTFP, Performance, Debug and More

Posted by Michael Posner on 16th March 2015

Possibly inspired my one of my blogs, Troy Scott, wrote a new whitepaper to help dispel the myths of physical FPGA-based prototyping. TTFP = Time To First Prototype

New Whitepaper, Busting the Myths Prototyping

I highly recommend this whitepaper as unlike my blogs, which I write mostly on the fly, this whitepaper obviously had a lot of thought put into it.

That’s it for the blog this week. I was traveling in the UK last week so I am a little jet lagged. While there I picked up a little UK history

http://poppies.hrp.org.uk/

It’s a ceramic poppy from the Tower of London remembers exhibit. It’s an amazing piece of history and I feel honored to be able to buy one.

I received another honor, this time from the hotel I stayed at

Mick is Mr Bacon

Yes, I am still known as Mr Bacon. This has a little to do with the fact that I love bacon and more so because I always seem to wear a T-Shirt that says BACON on the front of it.

I also had some fun with the rental car while trying to find parking one day. Below you can see my parking spot halfway up a hillside.

Mick gets crazy with parking spots

I’m not sure if you can see it or not but the back wheel is floating in the air. Fun, fun, fun.

Posted in FPGA-Based Prototyping, FPMM Methods, Humor, Milestones, Project management, Technical, Tips and Traps | Comments Off

Scared of Multi-FPGA Prototyping, Don’t Be !!!

Posted by Michael Posner on 25th January 2015

Random image of someone looking scared

Last week I spent a week in Japan visiting users to discuss their FPGA-based prototyping challenges and explain how Synopsys can help. My overall take-away of the visits was that many companies want to expand their current single FPGA-based prototyping to multi-FPGA but fear the challenges associated with this. The summary of what I explained was pretty simple but to the point. #1 Having a defined methodology, flow and tool set is key. #2 Yes Multi-FPGA is more complex but it’s not as steep of a learning curve as you may think. And that’s it…..

#1 Having a defined methodology, flow and tool set is key

In respect to methodology you of course can refer to the FPGA-based Prototyping Methodology Manual, FPMM. (English and Japanese versions, 英語版と日本語版) I used Google translate so I hope I didn’t just offend the whole of Japan. Read the FPMM and you will become an expert prototyper but we all know that in this age of technology a summary is always nice. This is why I blogged about 3 Phase Approach to Successful Prototyping a while back. Yes, this is the blog with the upside down pyramid which at the time I thought was a great way to show the progression down through a funnel. The three phases are “Make Design FPGA Ready”, this is all about making the ASIC RTL FPGA friendly. “Bring Up Functional Prototype”, this is where you want to get onto the hardware as quickly as possible so you can functionally validate the design. Finally “Optimize Prototyping Performance”, pretty self-explanatory really.

Synopsys' definition of the three phases of FPGA-based prototyping. Follow this methodogy for success

Along with a defined methodology you need to utilize a tool flow which is designed for prototyping. I was amazed in Japan that many companies still tried to use the FPGA vendor tools for prototyping. I have nothing against FPGA vendor tools, they are great for their job which is FPGA synthesis. When I asked about the challenges these customer faced it was the same story I have heard before, ASIC clock conversion, gated clocks, memories and for the few that did multi-FPGA the key challenge was clock/reset synchronization and pin multiplexing. If you want to go fast on the freeway you don’t buy a bicycle you buy a car, it’s the same with prototyping. If you want to prototype buy a tool set which is designed for the purpose. I blogged about ASIC Gated clock conversion a while back, Unlocking the Secrets of ASIC Clock Conversion, which is just one example of a tool set designed for prototyping. Search my blog and you will find a stack more examples of what is possible by the tools these days. You need a tool set which is more than just a FPGA synthesis tool, you need a tool set that understands your challenges and can help with automation and dedicated capabilities.

#2 Yes Multi-FPGA is more complex but it’s not as steep of a learning curve as you may think.

If you have never prototyped before I’m not going to tell you to start doing multi-FPGA prototyping straight away, too many variables to take on at once. Start small, create a single FPGA-based prototype of a subsystem of your design. Don’t fall into the trap of thinking you can get away with using the FPGA vendor tools (see above) use a dedicated FPGA-based prototyping tool. This is exactly why we provide ProtoCompiler DX as part of the HAPS-DX system. ProtoCompiler DX is everything you need to implement the prototype and more as it includes high visibility debug capabilities. Once you have a prototype up and running on a single FPGA, then it’s time to expand, but don’t bite off more than you can chew, again start small. My suggestion is that you do not add anything new to the design you already have operational. Simply select a block or two from the existing design and move them into a 2nd FPGA. Using your multi-FPGA prototype tool, such as ProtoCompiler, get familiar with partitioning and pin multiplex IP insertion. Get familiar with customizing the hardware to match the needs of your design. Abstract Partition Flow Advantage, this is an important step to ensure that you create the highest performance multi-FPGA prototype. Once you have the same design up and running on two FPGA’s and a design flow and expertise in place you are ready for greater things. Go off and be successful in multi-FPGA prototyping.

The weather was pretty nice in Japan, here is the view from the hotel I was staying at:

View from my hotel room

We had lots of nice meals out, can you guess what was served at this restaurant?

I wonder what you serve here?

We did a day trip to Shin-Osaka via the bullet train, Shinkansen, what a mean looking train

Bullet Train, the Shinkansen, pretty mean looking

Nice view of Mount Fuji on the way up

Mount Fuji as seen from train from Tokyo to Shin-Osaka

While the Japanese can build a train that goes 200 MPH they have the same problem as the rest of the world, horrible coffee. Luckily when we arrived the local team treated me to vending machine coffee

Yum, vending machine coffee...

Of course many may question my judgment for even trying train coffee and vending machine coffee. You have to remember I was jet lagged and this was better than no coffee….. but only marginally.

I met the star of the film, Big Hero6, Bay Max, well at least his inflatable body double

Mick meets Bay Max, the star of the film Big Hero6

The funny thing is that Bay Max the real character is also inflatable so what this really a body double or his clone?

Posted in FPGA-Based Prototyping, FPMM Methods, Getting Started, Technical, Tips and Traps, Use Modes | Comments Off

Coming To A Lab Soon: Xilinx VU440 FPGA Devices

Posted by Michael Posner on 16th January 2015

Xilinx Summary of the new UltraScale VU440 FPGA device capabilities for prototypers

In late 2013 I blogged about the newly announced Xilinx UltraScale devices, the VU440 specifically that will be the largest FPGA device on the market: http://blogs.synopsys.com/breakingthethreelaws/2013/12/xilinx-fpga%E2%80%99s-for-fpga-based-prototyping/

Well this week Xilinx officially announced that they have shipped the first samples of the VU440 devices: http://press.xilinx.com/2015-01-15-Xilinx-Delivers-the-Industrys-First-4M-Logic-Cell-Device-Offering-50M-Equivalent-ASIC-Gates-and-4X-More-Capacity-than-Competitive-Alternatives

Snippet from Xilinx Press release on the VU440 device and the fact that Synopsys received the first device samples

And check out who received the first of these samples…………………………… ok, you don’t need to read it, Synopsys did…….. We have optimized every generation of our HAPS prototyping systems for the highest system performance, greatest capacity while adding significant capabilities on top delivering prototyping specific features. We all know the FPGA device is a required component within the FPGA-based prototyping hardware but it’s not what defines or makes the solution useful. Anyone can slap an FPGA on a board but this does not help a prototyper as the device alone does not deliver the capabilities they require. Prototypers rely on a solution which includes a software implementation tool flow, integration between hardware and software accelerating time to operation, built in capabilities such as high speed pin multiplexing and high visibility debug to ease bug hunting while being modular and scalable. (side note: Synopsys offers exactly this…. just in case you didn’t know)

I recommend you also check out the VU440 demo video. It stars my friend Kirk from Xilinx who introduces the new device and the demo running ten ARM Cortex-A9 CPU’s, pretty impressive. http://www.xilinx.com/products/silicon-devices/fpga/virtex-ultrascale.html#uniquePlayer1

Over the coming weeks I’m going to focus my blogs on the capabilities that the new Xilinx UltraScale devices deliver and the impact they have to prototypers. As noted above, an FPGA alone does not deliver FPGA-based prototyping so I will discuss how the device capabilities are expected to be integrated and leveraged delivering a solution.

Oh, and just because Synopsys has received Xilinx sample devices don’t expect a new HAPS next week. Delivering a solution requires hardware development, software development and a huge amount of validation. But I’m confident that when you are ready to adopt, Synopsys will be ready to deliver…..

Posted in Admin and General, ASIC Verification, Bug Hunting, Debug, Early Software Development, FPGA-Based Prototyping, HW/SW Integration, In-System Software Validation, Man Hours Savings, Milestones, Technical, Tips and Traps | Comments Off

Unlocking the Secrets of ASIC Clock Conversion

Posted by Michael Posner on 13th December 2014

open-safe

Warning: Technical Content!

I read an online article this week which flagged an issue with FPGA-based prototyping, clock conversion. Clock conversion is one of the most important aspects to successful prototyping and this week’s blog is dedicated to sharing information enabling you to be successful. Specifically I will cover automated Gated Clock Conversion, GCC, as the user realizes the highest benefits. With automated gated clock conversion you don’t need to maintain a separate RTL code branch for prototyping, you use the golden RTL source. Clock conversion done right ensures the prototype runs at the highest performance functionally equivalent to the source. If you look at the data from the Channel Media survey that Synopsys had conducted you see that for large FPGA-based prototyping, clock conversion is a major challenge.

Clock Conversion, the #1 challenge facing prototypers who do larger than 10M ASIC gate prototyping

Hold on, I forgot to cover why clock conversion is needed for FPGA-based prototyping. It’s one of the three laws, ASIC are not the same as FPGA’s, specifically in this case FPGA’s do not have the same clock resources like ASIC’s do. ASIC designs often use clock gating to reduce dynamic power and have complex clock logic to generate numerous internal clocks. In the ASIC flow, users do Clock Tree Synthesis to balance all the clock paths between the sources and destinations and avoid clock skews between them. The problem is the number of ASIC clocks in the design typically exceed the number of global clock lines available in the FPGAs. There are a limited number of dedicated global clock lines in FPGA devices and Global clock lines cannot accommodate clock generating and gating logic. Thus GCC is needed to convert these ASIC clock structures to FPGA comparable structures. You could do this manually but that’s time consuming and error prone.

One of the three laws of FPGA-based prototyping, ASIC clocks exceed the number of FPGA clocks

In Emulation oversampling type techniques are used to solve this problem, this is where all clocks are resolved to one synchronous clock source and all clocks are driven from derivatives of this clock. The benefit of this technique is that the conversion is fast and practically any type of clock tree structure can be handled. The main two disadvantages are #1 you tank performance as the system frequency is dictated by the slowest clock. #2 the design loses some fidelity as all clocks are synchronous to each other which may not reflect the true asynchronous clock behavior hiding issues in clock domain crossing circuits. Techniques similar to this such as the HAPS Clock Optimization in ProtoCompiler (I think I’ll blog about HAPS Clock Optimization in the future but for today I’ll focus on Gated Clock Conversion) which map clocks to HAPS hardware resources, are getting popular in FPGA-based prototyping as they can help reduce the time to first prototype enabling a prototype to be handed off to the software teams quickly. It will not have the high performance expected by the software engineers but it’s available quickly, handles almost any ASIC clock structures and this gives the prototype engineers a little breathing space to complete the high performance version.

Oversampling, the typical method used by emulation to handle clocks

Gated Clock Conversion, GCC, converts ASIC clock structures to FPGA friendly structures mapped to FPGA clock resources. GCC also needs to handle timing violations due to clock skew created because of clock gating logic. These violations are introduced on paths where the source and destination flops are driven by different clocks. Data from the source may reach the destination quicker/later than the clock resulting in hold/setup time violations in many paths. GCC has to ensure that there is no clock skew between two synchronous clock domains. The GCC capabilities of ProtoCompiler directly addresses both these conversion challenges in a fully automated fashion. ProtoCompiler maps to FPGA resources and moves the generated clock and gated clock logic from the clock pin of the sequential elements to the enable pins. This includes supporting implementation of these structures across block boundaries and across multiple FPGAs as part of partitioning.

Hold time violation example

Tool support of automated gated clock conversion is not a milestone it’s a journey as ASIC coding styles are continually evolving and the tools need to keep pace. ProtoCompiler has an extensive portfolio of supported structures including, but not limited to, Generated Clock, Gated Clock, Integrated Clock Gating Cells, Complex Sequential Cells, Instantiated Cells, Mixed Async Controls, Data Latches and MUX / XOR structures. With the correct clock constraints ProtoCompiler should automatically identify these gated clock structures and convert them to FPGA friendly structures. Below is an example of generated clock identification and the result of the automatic conversion.

Generated clock conversion example showing the result after ProtoCompiler automated conversion

In summary clock conversion is essential to successful prototyping. The ProtoCompiler Clock Conversion capabilities moves the generated clock and gated clock logic from the clock pin of the sequential elements to the enable pins, allowing sequential elements to be tied directly to the source clock, removing skew issues and reducing the number of clock sources in the design making it FPGA-based prototype friendly. Automated Gated Clock Conversion is just one of the many capabilities that ProtoCompiler delivers and is essential for prototypers.

Summary list of ProtoCompiler capabilites and benefits

Don’t forget that the FPGA-based Prototyping Methodology Manual, FPMM, has a section to help understand clock conversion and other ASIC design structure handling. Last week I had the pleasure to hang out with Rene Richter, one of the authors of the FPMM. Rene signed a book copy for me, this copy could be yours if you comment and answer the following question

How many HAPS systems has Synopsys shipped and to how many customers?

A signed copy of the FPMM

Answer the question by comment and if you get the answer right I will contact you to get your shipping addresss.

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Posted in ASIC Verification, FPGA-Based Prototyping, Man Hours Savings, Technical, Tips and Traps | 2 Comments »

FPMM Book Achieves Major Milestone, More than 8000 Copies Distributed

Posted by Michael Posner on 14th November 2014

FPMM Book Cover. FPMM is the holy grail of FPGA-based prototyping unlocking the secrets to successful prototyping

Recently Synopsys promoted that “Synopsys Virtual Prototyping Book Achieves Milestone of More Than 3000 Copies in Distribution to Over 1000 Companies” – http://news.synopsys.com/2014-11-05-Synopsys-Virtual-Prototyping-Book-Achieves-Milestone-of-More-Than-3000-Copies-in-Distribution-to-Over-1000-Companies Virtual Prototyping continues to gain momentum including Hybrid Prototyping, which combines Virtual Prototyping with FPGA-based prototyping. The VP book statistics prompted me to have a look at the FPGA-based Prototyping Methodology Manual, FPMM statistics.

To date there have been over 6000 FPMM downloads across 2800 different companies and over 2500 free books handed out. WOW. I expect a bit of overlap between the two but still that’s got to be over 8000 copies distributed. I’m happy that the FPMM has been able to help so many engineers around the world.

Looking at the challenges facing these prototypers, below image, you can see that conversion of ASIC to FPGA is still rated as #1.

Challenges identified by prototypers who downloaded the FPMM. These challenges are solved by integration of HW and SW prototyping tools such as the Synopsys HAPS and ProtoCompiler products

Actually the #2 challenge, clocking issues, really falls into the this same category. As previously blogged, these challenges are not solved with just software or just hardware changes, they are solved by integration. When the software has built in understanding of the hardware and when the hardware can be customized to the needs of the SoC many of the challenges disintegrate.

A great example of the value of integration is the DesignWare IP Prototyping Kits which are part of the Synopsys IP Accelerated Initiative. DesignWare IP prototyping kits deliver a comprehensive IP subsystem which enables immediate productivity for both Hardware and Software engineers. Individually IP & FPGA-based prototyping deliver value but when combined the value is increased. It’s like the 1+1 = 3.

Talking of IP, DesignWare USB 3.1 IP is now available. http://www.synopsys.com/Company/PressRoom/Pages/usb-3-1-news-release.aspx . I have been talking about USB 3.1 for a while now and blogged about it here. You can also find a video of the DesignWare IP for USB 3.1 running on the HAPS-70 systems here https://www.youtube.com/watch?v=isQ7cvuyoTw

Enjoy

Do you have a topic you would like me to blog about? If so, drop me a comment and I’ll pop it in the queue.

Posted in FPGA-Based Prototyping, FPMM Methods, Getting Started, IP Validation, Technical, Tips and Traps | 1 Comment »

3 Phase Approach to Successful Prototyping

Posted by Michael Posner on 30th October 2014

Synopsys' three phase approach, best practices and methodology for successful prototyping

In previous blogs I have spoken a lot about automation, features and capabilities which accelerate time to operational prototype and deliver higher performance enabling you to run more software against your design representation. These capabilities are designed to reduce the need for prototyping expertise and effort……..  but not to zero. Anyone who tells you that no expertise or effort is needed is not telling you the whole truth. This was the basis of this blog, “Breaking the three laws” of which the first law is ASIC are FPGA Hostile! Who can tell me what the other two laws are? I know but this is like a quiz for my readers.

Pictures in the blog are posted large so they are easier to read, click on the picture to see the full view version.

Synopsys has created a simple three phase definition for FPGA-based prototyping, including methodology guidelines and I am happy to share them with you. The three phases split into 1. Make Design FPGA Ready. 2. Bring Up Functional Prototype. 3. Optimize Prototype Performance. Follow these three phases and you will be on a path for FPGA-based prototyping success.

Synopsys' definition of the three phases of FPGA-based prototyping. Follow this methodogy for success

Make Design FPGA Ready

This is probably the most important step as the rule of thumb is garbage in, garbage out. There is only so much automation a tool can deliver so understanding the basic needs and best practices for FPGA-based prototyping is essential. Synopsys ProtoCompiler can help here with automated ASIC to FPGA translation, clock conversion and replication as needed. However you should always follow the best practices defined here to yield better results in the final implementation. Don’t forget, full best practices can be found in the FPMM, FPGA-based Prototyping Methodology Manual.

Synopsys' Phase 1, Make Design FPGA Ready. Automation through ProtoCompiler

Bring Up Functional Prototype

Once code is prepared the bring up functional prototype phase is entered. This is the phase with the goal of getting the prototype up and running as quickly as possible, TTFP, enabling the team to hand off a platform to the software developers. The faster they get a platform the most productive they can be. Even if you have traded off a little performance to get the fastest time to prototype your software team will thank you for the fast enablement. ProtoCompiler and HAPS helps here, especially in the partition phase, I recently blogged about this: Abstract Partition Flow Advantage. Another important best practice is to plan your debug needs upfront in this phase, don’t treat it as an afterthought. This is exactly why in the ProtoCompiler flow debug is highlighted ensuring you at least give it some thought.

Synopsys' Phase 2, Bring Up Functional Prototype, use HAPS and ProtoCompiler for fastest time to operational prototype

Optimize Prototype Performance

As you have already delivered an operational prototype to your software team you have a little breathing space now to focus on performance optimizations. In the fast turn-around abstract partition flow ProtoCompiler might have identified some bottlenecks that you skipped past in order to achieve fastest time to prototype. Now you have time to focus on these and other areas of the FPGA-based prototype to squeeze the most out of the solution. An example of this was shared with me recently where the prototype was fully operational at 9 MHz but with a little more effort, new partition and careful analysis of critical paths, the prototype performance was increased to 13 MHz. What a great improvement.

Synopsys' Phase 3, Optimize Prototype Performance. Using HAPS and ProtoCompiler will enable the highest possible customization for performance

So there it is, three simple phased approach ensuring successful prototyping, enjoy!

Happy Halloween, here is the costume that I built, I call it Atomic Dinosaur. I am a construction spray foam  master and it has LED lights down it’s back too!

Mick's Atomic Dinosaur costume

That’s some crazy eyes I’ve got going on…………….

Posted in FPGA-Based Prototyping, FPMM Methods, Getting Started, Technical, Tips and Traps | Comments Off

The Secret Ninja-Fu for Higher Performance Prototype Operation

Posted by Michael Posner on 5th April 2014

Not many people know this but I am a FPGA-based prototyping Ninja-Fu master. What super power do I have you ask? I have the power to enable higher performance prototype operation and in this week’s blog I am sharing this ancient secret power with you. Wow, the start of this blog sounds like the bio from a really bad “B” movie, it definitely seemed funnier in my mind, then again everything seems funnier in my mind. There is actually some seriousness to this blog as I really am going to share the not so secret method to enable higher performance in your FPGA-based prototypes.

First, let’s study a typical SoC, this case it’s ~40-50 Million ASIC gates. I chose this design as it’s easier to explain but the principle for higher performance operation is even more important for larger more complex SoC’s. Our example SoC includes a CPU with tightly coupled GPU and DDR3-based memory subsystem, PCIe high performance interface, SRAM scratch pad storage, global bus, custom logic block (your SoC’s special sauce for instance) and a number of lower performance peripherals

When you model such an SoC in an FPGA-based prototype, even with the largest FPGA’s, you need to partition the design. Partition is to split up the design across multiple FPGA’s. The challenge is that the SoC design blocks have more signals than you have FPGA pins (Hey that’s one of the three laws of the breaking the three laws blog). We all know that when you partition such a design you need to insert pin multiplexing to manage the many signals over the limited FPGA pins. As I am writing this I suddenly realized I have shared the secret of higher performance prototyping before, here, anyway, this blog is way cooler so I’ll continue writing.

The challenge of partitioning this design is that due to the tightly coupled CPU/GPU you end up with many signals spanning out from a small number of design blocks. Lets assume the CPU and GPU are partitioned across two FPGA’s. If all you are prototyping is these two blocks then with the use of pin multiplexing you can connect the two blocks together. The challenge of this prototyping project is that you are also modeling the other design blocks as you want to validate the software and use that to validate your RTL design blocks. This means you end up with the SoC partitioned across four FPGA’s which forces even more connections between FPGA’s.

The picture above is a representation of the partition, the raw IO interconnect usage and the number of external IO’s required for daughter boards. Suddenly you see not only the sheer volume of interconnect needed but also the number of individual connectors required to create such an partition. Just look at FPGA 2, it’s packed with IO and daughter boards. You could try and partition the design in a different way but it’s sure to tank the performance as the GPU needs to be tightly coupled to the DDR3 memory and the CPU requires a tight link to the PCIe interface. If you sacrifice physical IO between FPGA 1 and FPGA 2 you will end up with very high pin mux ratios resulting in very low system performance.

If you were to try and model this SoC on a board with a fixed interconnect between FPGA’s or forced to use a board with great big IO connectors you would physically not be able to support SoC designs like this. With the fixed interconnect board, even if you could work out a partition, you will have to force fit your SoC interconnect topology across a fixed number of IO’s resulting in high mux ratio’s thus low performance. In addition it’s unlikely that the board would have the number of available external connector IO to support the SoC’s external interfaces for daughter boards. It’s similarly bad on a board with high pin count connectors.  Using our typical SoC as the example, if the FPGA-based prototyping board has FMC like connectors, ~150 IO’s per connector, you would need ten connectors to support the required interconnect and daughter boards for the tightly connected CPU/GPU. Whoops, I know of no board that has this many connectors. Again you would be forced to use very high pin multiplexing tanking the performance and making the platform worthless.

Now look at the HAPS-70 S48, the Synopsys four FPGA FPGA-based prototyping system. This type of typical SoC design is the reason why the HAPS-70 systems expose all the FPGA’s pins to HapsTrak 3 (HT3) connectors. HT3 granularity is 50 FPGA IO’s per connector and are bank matched to the Xilinx Virtex-7 2000T banks and Super Logic Regions (SLR’s). This granularity is the “not so secret” enabler for SoC prototyping and the key to higher performance operation.

Now you can see that not only do you have the connector granularity to tailor the interconnect to the requirements of the SoC design but you also have ample connectors to support the external IO daughter boards. You can create a very dense interconnect between FPGA 1 and FPGA 2 supporting the tightly coupled CPU/GPU and you don’t need pin multiplexing as you have the physical number of IO’s needed. At the same time you can support all the other interconnect requirements to the other FPGA’s and the required daughter boards.

Hold on, there’s more….

You have ample connectors to setup the prototype with the needed JTAG debugger daughter board connecting your software debugger to the CPU. You have ample connectors to add real time debug to the platform. Real time debug is when you extract signals from the design and route them to a debugger daughter board which you connect a logic analyzer to. Oh and you can also add on some HAPS Deep Trace Debug memory so you can capture seconds of debug visibility. So not only is the HAPS system higher performance but the hardware architecture is the enabler for prototyping typical SoC’s. If you are smart you will also understand that as the SoC grows in size and requires more FPGA partitions that the HAPS flexible interconnect architecture becomes even more important. Below you can see a picture of the HAPS-70 S96, eight FPGA system, deployed for SoC prototyping enabling earlier software development and system validation

Now you have the secret Ninja-Fu.

I’ve pretty much finished my large tracked vehicle project which I featured last week. I plan to add a controllable shovel and other attachments to the front but I got side tracked building a new project.

This is a very small shovel dozer, you can see how small it is as it’s sitting on top of my home-built tracked vehicle. (Or maybe my tracked vehicle is just very big). You this little shovel dozer come from a kit but rather than using the supplied hard wired connection I’m going to retro fit this model with some tiny radio controlled electronics. I have not built the RC control yet and with upcoming business travel I’m not sure when I am going to get a chance to. I’ll be sure to post an update when this latest project is finished.

Posted in Debug, Early Software Development, FPGA-Based Prototyping, HW/SW Integration, Mick's Projects, System Validation, Technical, Tips and Traps | Comments Off

Prototyping wearables and the Internet of Things (IoT)

Posted by Michael Posner on 16th March 2014

Is this the future of wearable technology?

LOL, no…. well maybe…..

There are lots of questions on if wearables will bring the end of the Smartphone, I personally think these two technologies will co-exist. I like the idea of wearing my technology but there are many people that don’t thus there should be a place for both technologies for a while yet. Of course for anyone who travels a lot like me they will know that the airport security creates a new issue not previously encountered. I use a fitbit which is a small step tracker and I wear this on my trouser (pant) pocket. It pretty much lives in this spot and I’ve almost put it through the washing machine when I’ve forgotten to take it off. The problem is that this little device has become a part of my life and when going through airport security I’ve also forgotten to take it off which leads to an extra search pat down. A simple solution to this would be for me to remember to take it off but it would be nice if these devices are security certified of something like that.

When it comes to prototyping these deeply embedded SoC designs you will find out that while the form factor is small and simple the SoC designs are not. These designs are multi-million ASIC gates so when they are prototyped using FPGA’s the challenges of handling non-FPGA code, multi-FPGA partitioning and prototype assembly must be overcome. I visited a load of customers last week while traveling internationally and the common theme at the meetings was discussion around how to enable complex FPGA-based prototyping without the need for in-depth specific expertise. The first place to start is to put a methodology in place to define a flow supporting FPGA-based prototyping making a part of the larger SoC project. The FPGA-based Prototyping Methodology Manual, FPMM, is the perfect place to start in defining what is needed as part of this flow.  

I had the pleasure of traveling with Rene Richter, one of the co-authors of the FPMM. In the picture above you can see him explaining the basis of multi-FPGA partitioning and how to utilize pin multiplexing. His expertise helped a lot of customers last week but he was the first to say that everything he explained was already documented in the FPMM.

This week’s call to action, download the FPMM if you have not already done so………… and read it.

I was thinking that it might be time to work on the 2nd revision, updating the FPMM with information on how FPGA-based prototyping has evolved over the last couple of years, what do you think? What do you think has changed in FPGA-based prototyping which should be documented?

Posted in ASIC Verification, FPGA-Based Prototyping, FPMM Methods, Getting Started, Technical, Tips and Traps | Comments Off

Reducing Risk with Pre-Silicon Demonstrations

Posted by Michael Posner on 17th January 2014

This week’s blog is going to show you how FPGA-based prototyping delivers a whole new level of WOW factor to a new product introduction. Oh, and this also sends a message of reduced risk to the prospect customer. OK, so here we go, recently Synopsys announced the industry’s first USB Superspeed 3.1 10 Gb/s platform to platform, host to device, data transfer demonstration. Here is a link to the news release.

http://news.synopsys.com/2013-12-10-Synopsys-Demonstrates-Industrys-First-SuperSpeed-USB-10-Gbps-Platform-to-Platform-Host-Device-IP-Data-Transfer

It’s one thing to make claims in paper but delivering a real demonstration of the capability adds a whole level of credibility to the data being presented. Here are the set of videos of the real demonstrations of USB 10G transfers

 The Synopsys HAPS and DesignWare IP was also used by the USB-IF to demonstrate the new USB Superspeed 3.1 10Gb/s capability:  http://www.anandtech.com/show/7652/usbif-updates-us-on-type-c-connector-demonstrates-usb-superspeed-31-transfers

 WOW……….

I’ve mentioned this in a couple of my blogs that in addition to FPGA-based prototypes being used for early software development, HW/SW integration, System validation they are the single best pre-silicon method to demonstrate new product capabilities to your prospect customers. Seeing the product in action is far more credible and valuable than simply reading a product pitch or spec sheet. A real pre-silicon demonstration leaves the prospect customer with a feeling of reduced risk with your new product as they just saw it and played with it. (it feels far more real) The same demonstration platforms can also be delivered to the prospect customer enabling a more complete evaluation or for early software development of applications that will sit on top of this new product.

Are you using FPGA-based prototypes to deliver pre-silicon demonstrations?

Also, did you like this shorter blog or my longer more in-depth blogs which I did the last couple of times?

Posted in FPGA-Based Prototyping, Tips and Traps | Comments Off