FPGA

378 Articles

A Better Way To Plug A CPLD Into A Breadboard

February 4, 2016 by 62 Comments

If you read my first post about a simple CPLD do-it-yourself project you may remember that I seriously wiffed when I made the footprint 1” wide, which was a bit too wide for common solderless breadboards. Since then I started over, having fixed the width problem, and ended up with a module that looks decidedly… cuter.

To back up a little bit, a Complex Programmable Logic Device (CPLD) is a cool piece of hardware to have in your repertoire and it can be used to learn logic or a high level design language or replace obsolete functions or chips. But a CPLD needs a little bit of support infrastructure to become usable, and that’s what I’ll be walking you through here. So if you’re interested in learning CPLDs, or just designing boards for them, read on!

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Sort Faster With FPGAs

January 20, 2016 by 108 Comments

Sorting. It’s a classic problem that’s been studied for decades, and it’s a great first step towards “thinking algorithmically.” Over the years, a handful of sorting algorithms have emerged, each characterizable by it’s asymptotic order, a measure of how much longer an algorithm takes as the problem size gets bigger. While all sorting algorithms take longer to complete the more elements that must be sorted, some are slower than others.

For a sorter like bubble sort, the time grows quadradically longer for a linear increase in the number of inputs; it’s of order O(N²).With a faster sorter like merge-sort, which is O(N*log(N)), the time required grows far less quickly as the problem size gets bigger. Since sorting is a bit old-hat among many folks here, and since O(N*log(N)) seems to be the generally-accepted baseline for top speed with a single core, I thought I’d pop the question: can we go faster?

In short — yes, we can! In fact, I’ll claim that we can sort in linear time, i.e a running time of O(N). There’s a catch, though: to achieve linear time, we’ll need to build some custom hardware to help us out. In this post, I’ll unfold the problem of sorting in parallel, and then I”ll take us through a linear-time solution that we can synthesize at home on an FPGA.

Need to cut to the chase? Check out the full solution implemented in SystemVerilog on GitHub. I’ve wrapped it inside an SPI communication layer so that we can play with it using an everyday microcontroller.

To understand how it works, join us as we embark on an adventure in designing algorithms for hardware. If you’re used to thinking of programming in a stepwise fashion for a CPU, it’s time to get out your thinking cap!

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Shmoocon 2016: GPUs And FPGAs To Better Detect Malware

January 17, 2016 by 40 Comments

One of the big problems in detecting malware is that there are so many different forms of the same malicious code. This problem of polymorphism is what led Rick Wesson to develop icewater, a clustering technique that identifies malware.

Presented at Shmoocon 2016, the icewater project is a new way to process and filter the vast number of samples one finds on the Internet. Processing 300,000 new samples a day to determine if they have polymorphic malware in them is a daunting task. The approach used here is to create a fingerprint from each binary sample by using a space-filling curve. Polymorphism will change a lot of the bits in each sample, but as with human fingerprints, patterns are still present in this binary fingerprints that indicate the sample is a variation on a previously known object.
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Zedboard Multiport Ethernet

January 8, 2016 by 9 Comments

The Zedboard uses Xilinx’s Zynq, which is a combination ARM CPU and FPGA. [Jeff Johnson] recently posted an excellent two-part tutorial covering using a Zedboard with multiple Ethernet ports. The lwIP (light-weight Internet Protocol) stack takes care of the software end.

Vivado is Xilinx’s software for configuring the Zynq (among other chips), and the tutorial shows you how to use it. The Ethernet PHY is an FPGA Mezzanine Card (FMC) with four ports that is commercially available. The project uses VHDL, but there is no VHDL coding involved, just the use of canned components.

The real issue when using an FPGA and a CPU is the interface between the processor and the FPGA circuitry. In this case, the ARM standard AXI bus does this task, and the Ethernet component properly interfaces to that bus. The IP application in the second part of the post is an echo server.

We’ve seen the Zynq used in flying machines and also in a music synthesizer. Although this project doesn’t use any Verilog or VHDL that you create, it is still a great example of configuring using Vivado and using common components in a design.

BabyBaby: A 1948 Computer On An FPGA

January 6, 2016 by 11 Comments

The Manchester Baby seems simple today. A 32-bit machine with 32 words of storage. It wasn’t meant to be a computer, though, but a test bed for the new Williams tube storage device. However, in 1948, it executed stored programs at about 1,100 instructions per second. The success of the machine led to a series of computers at Manchester University and finally to the first commercially available computer, the Ferranti Mark I.

[Dave] is lucky enough to volunteer to demonstrate the Baby replica at Machester’s Museum of Science Industry. He wanted his own Baby, so he used a Xilinx FPGA board to build a replica Baby named BabyBaby. Although it runs at the same speed as the original, it is–mercifully–much smaller than the real machine.

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FPGA To Ethernet Direct

January 2, 2016 by 19 Comments

When [iliasam] needed an Ethernet connection, he decided to see how much of the network interface he could put in the FPGA logic. Turns out that for 10 Base-T, he managed to get quite a bit inside the FPGA. His original post is in Russian, but automatic translation makes a passable attempt at converting to English.

This is a classic trade off all FPGA designers face: how much external logic do you use for a particular design. For example, do you add memory to the PCB, or use FPGA resources as memory? Each has its advantages and disadvantages (that’s why it is a trade off). However, if you are trying to keep things cheap, slashing external circuitry is often the way to go.

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32C3: A Free And Open Source Verilog-to-Bitstream Flow For ICE40 FPGAs

December 29, 2015 by 10 Comments

[Clifford] presented a fully open-source toolchain for programming FPGAs. If you don’t think that this is an impressive piece of work, you don’t really understand FPGAs.

The toolchain, or “flow” as the FPGA kids like to call it, consists of three parts: Project IceStorm, a low-level tool that can build the bitstreams that flip individual bits inside the FPGA, Arachne-pnr, a place-and-route tool that turns a symbolic netlist into the physical stuff that IceStorm needs, and Yosys which synthesizes Verilog code into the netlists needed by Arachne. [Clifford] developed both IceStorm and Yosys, so he knows what he’s talking about.

What’s most impressive is that FPGAs aren’t the only target for this flow. Because it’s all open source and modifiable, it has also been used for designing custom ASICs, good to know when you’re in need of your own custom silicon. [Clifford]’s main focus in Yosys is on formal verification — making sure that the FPGA will behave as intended in the Verilog code. A fully open-source toolchain makes working on this task possible.

If you’ve been following along with [Al Williams]’s FPGA posts, either this introduction or his more recent intermediate series that are also based on the relatively cheap Lattice iCEStick development kit, this video is a must-watch. It’s a fantastic introduction to the cutting-edge in free FPGA tools.