VexRiscv: A Modular RISC-V Implementation for FPGA

Since an FPGA is just a sea of digital logic components on a chip, it isn’t uncommon to build a CPU using at least part of the FPGA’s circuitry. VexRiscv is an implementation of the RISC-V CPU architecture using a language called SpinalHDL.

SpinalHDL is a high-level language conceptually similar to Verilog or VHDL and can compile to Verilog or VHDL, so it should be compatible with most tool chains. VexRiscv shows off well in this project since it is very modular. You can add instructions, an MMU, JTAG debugging, caches and more.

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You are Go for FPGA! is accepting beta applications for its environment to configure FPGAs using Go. Yes, Go is a programming language, but the software converts code into FPGA constructs, so you don’t need Verilog or VHDL. Since Go supports concurrent routines and channels for synchronization and communications, the parallel nature of the FPGA should fit well.

According to the project’s website, the tool also allows you to reconfigure the FPGA on the fly using a cloud-based build and deploy system. There isn’t much detail yet, unless you get accepted for the alpha. They claim they’ll give priority to the most interesting use cases, so pitching your blinking LED project probably isn’t going to cut it. There is a bit more detail, however, on their GitHub site.

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FPGA Rescues Scope From The Dumpster

I’m always on the lookout for a quality addition to my lab that would respect my strict budget. Recently, I’ve found myself pushing the Hertz barrier with every other project I do and hence desperately wanted a high bandwidth scope. Unfortunately, only recently have 70 MHz to 100 MHz become really affordable, whilst a new quad channel oscilloscope in the 500 MHz to 1 GHz range still costs a fortune to acquire. My only option was to find an absolute miracle in the form of an old high bandwidth scope.

It seemed the Gods of Hand Me Down electronics were smiling upon me when I found this dumpster destined HP 54542C. It appeared to be in fairy good shape and was the Top Dog in its day. But something had to be broken right? Sure enough, the screen was clearly faulty and illegible. Want to know how I fixed it? Four letters: FPGA.

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HDMI Out on the Gameboy Advance

The Gameboy line of handheld systems from Nintendo have been wildly popular, but lack one major thing – a video output. This can be troublesome if you’d like to view the games on a bigger screen, for more comfortable gaming sessions or detail work like producing chiptunes. One option is to use the Gameboy Player for the Gamecube, however that system’s age means you’re out of luck if you want a crisp, clear picture on a modern digital display. Wouldn’t it be great if you could get HDMI output from a Gameboy Advance Instead?

A family resemblance?

When it comes to working with video signals, FPGAs can’t be beat. [Stephen] leverages an FPGA in this project to read the GBA’s video signals and convert them to the modern digital format. Unfortunately, it’s not a seamless install – limited space means the GBA’s screen must be entirely removed, replaced with the adapter in a manner resembling the terrifying Facehugger.

Packaging aside, the output from the device is nothing short of stunning – the graphics are absolutely crystal clear when displayed on a modern HDMI television. This is because the FPGA is capturing the exact digital output from the GBA, and piping it out as HDMI – there’s no analog fuzziness, conversions or noise to spoil the image. Output is a tasty 1280×720, upscaled from the GBA’s original resolution. For more details, check out the forum thread where [Stephen] runs through the build.

The only thing missing  is details – we’d love to know more about the exact hardware used, and any trials and tribulations during the build! As far as we can tell, the build doesn’t stop at just video – a SNES controller is used instead of the original buttons, and we have a feeling sound is being passed over the HDMI channel as well sound is piped to the TV from the GBA’s headphone port.

It’s great to see these projects for old hardware come out – modern hardware has the muscle to achieve things previously unthinkable on retro consoles. We’ve seen similar projects before – like adding VGA to an original Game Boy.

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Run From the Sound of Footsteps in Blind Game of Tag

The human auditory system is a complex and wonderful thing. One of its most useful features is the ability to estimate the range and direction of sound sources – think of the way people instinctively turn when hearing a sudden loud noise. A team of students have leveraged this innate ability to produce a game of tag based around nothing but sound.

The game runs on two FPGAs, which handle the processing and communication required. The chaser is given a screen upon which they can see their own location and that of their prey. The target has no vision at all, and must rely on the sounds in their stereo headphones to detect the location of the chaser and evade them as long as possible.

The project documentation goes into great detail about the specifics of the implementation. The game relies on the use of the Head Related Transfer Function – a function related to how the ear picks up sounds relative to their position. This allows the FPGA to simulate the chaser’s footsteps, and feed the audio to the target who perceives the chaser’s position purely by sound.

It’s a great example of a gameplay mechanic that we’d love to see developed further. The concept of trying to find one’s way around by hearing alone is one which we think holds a lot of promise.

With plenty of processing power under the hood, FPGAs are a great choice for complex audio projects. A great project to try might be decoding MP3s.


An Education on SoC using Verilog

[Bruce Land] is one of those rare individuals who has his own Hackaday tag. He and his students at Cornell have produced many projects over the years that have appeared on these pages, lately with FPGA-related projects. If you only know [Land] from projects, you are missing out. He posts lectures from many of his classes and recently added a series of new lectures about developing with a DE1 System on Chip (SoC) using an Altera Cyclone FPGA using Verilog. You can catch the ten lectures on YouTube.

The class material is different for 2017, so the content is fresh and relevant. The DE1-SOC has a dual ARM processor and boots Linux from an SD card. There are several labs and quite a bit of background material. The first lab involves driving a VGA monitor. Another is a hardware solver for ordinary differential equations.

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Synthesizing Strings on a Cyclone V

Cornell students [Erissa Irani], [Albert Xu], and [Sophia Yan] built a FPGA wave equation music synth as the final project for [Bruce Land]’s ECE 5760 class.

The team used the Kaplus-Strong string synthesis method to design a trio of four-stringed instruments to be played by the Cyclone V FPGA. A C program running on the development board’s ARM 9 HPS serves as music sequencer, controlling tempo and telling the FPGA which note to play.

The students created versions of four songs, including “Colors of the Wind” from the Pocahantas soundtrack, “Far Above Cayuga’s Waters” (Cornell’s alma mater) and John Legend’s “All of Me”. A simple GUI allows the viewer to select a song and to choose which instrument or instruments to play, providing multiple variations for each song.

Thanks, [Bruce]!

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