Retrocomputing With Open Source FPGAs

August 28, 2017 by Brian Benchoff 27 Comments

A few years ago, we saw the reverse engineering of the Lattice iCE40 bitstream, opening the door to a completely Open Source development tool chain for FPGAs. This was an astonishing amount of work from [Clifford Wolf], [Mathias Lasser], and [Cotton Seed], but since then we haven’t seen a whole lot from Project IceStorm. Now, that’s about to change, and in the coolest way possible. [hoglet] is retrocomputing on an ICE40 development board.

This is an implementation of the Acorn Atom on a myStorm BlackIce board. This board is basically just a Lattice iCE40 FPGA, a few support components, and a bunch of pin headers, some of which are in the not-so-handy Arduino pinout footprint. By porting some Acorn Atom implementations and a 6502 core to verilog, [hoglet] was able to stuff a cool old retrocomputer onto an Open Source FPGA development board. Video output is through a resistor DAC driving a VGA cable, and keyboard input is through PS/2.

Just about everything about this Open Source implementation of the Acorn works, and there’s still a lot left in the iCE40 FPGA. [hoglet] is able to run the 6502 core at 25MHz, which means just about every 6502-based system should be able to run on the BlackIce board.

TinyFPGA Is A Tiny FPGA Board

July 31, 2017 by Al Williams 40 Comments

We recently noticed an open source design for TinyFPGA A-Series boards from [Luke Valenty]. The tiny boards measure 18 mm by 30.5 mm and are breadboard friendly. You can choose a board that holds a Lattice Mach XO2-256 or an XO2-1200, if you need the additional capacity.

The boards have the JTAG interface on the side pins and also on a top header that would be handy to plug in a JTAG dongle for programming. The tiny chips are much easier to work with when they are entombed in a breakout board like this. Bigger boards with LEDs and other I/O devices are good for learning, but they aren’t always good for integrating into a larger project. The TinyFPGA boards would easily work in a device you were prototyping or doing a small production run.

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Game Gear HDMI With SNES Controller

July 23, 2017 by Bryan Cockfield 10 Comments

With its backlit color screen and Master System compatibility, the Game Gear was years ahead of its main competition. The major downside was that it tore through alkaline batteries quickly, and for that reason the cheaper but less equipped Game Boy was still able to compete. Since we live in the future, however, the Game Gear has received new life with many modifications that address its shortcomings, including this latest one that adds an HDMI output.

The core of the build is an FPGA which is used to handle pixel decoding and also handles the HDMI output. The FPGA allows for a speed high enough to handle all the data that is required, although [Stephen] still has to iron out some screen-filling issues, add sound over HDMI, and take care of a few various pixel glitches. To turn this hack into a complete hodgepodge of adapters, though, [Stephen] has also added an SNES controller adapter to the Game Gear as well. Nintendo has featured Sonic in many of its games, so although we may have disagreed back in the early 90s we think that this Sega/Nintendo pairing is not crossing any boundaries anymore.

Game Gears have had their share of other modifications as well to make them more capable as a handheld system than they were when they were new. We’ve also seen them turned into a console system (they were Master System compatible, after all) and converted into other things entirely, too.

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VexRiscv: A Modular RISC-V Implementation For FPGA

July 21, 2017 by Al Williams 16 Comments

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!

June 14, 2017 by Al Williams 39 Comments

Reconfigure.io 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

June 1, 2017 by Adil Malik 62 Comments

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

May 30, 2017 by Lewin Day 35 Comments

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?

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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