dsp

42 Articles

Reverse-Engineering Forgotten Konami Arcade Hardware

June 28, 2022 by 4 Comments

When fully-3D video games started arriving in the early 90s, some companies were more prepared for the change than others. Indeed, it would take nearly a decade of experimentation before 3D virtual spaces felt natural. Even then, Konami seems to have shot themselves in the foot at the beginning of this era with their first foray into 3D arcade games. [Mog] shows us the ins-and-outs of these platforms while trying to bring them back to life via MAME.

These arcade machines were among the first available with fully-3D environments, but compared to offerings from other companies are curiously underpowered, even for the time. They include only a single digital signal processor which is tasked with calculating all of the scene geometry while competing machines would use multiple DSP chips to do the same job. As a result the resolution and frame rate are very low. Nonetheless, [Mog] set out to get it working in MAME.

To accomplish this task, [Mog] turned to a set of development tools provided to developers for Konami in the early 90s which would emulate the system on the PCs of the time. It surprisingly still worked on Windows 10 with minor tweaking, and with some other tools provided over the decades of others working on MAME these old Konami machines have some new life with this emulator support.

Not everything works perfectly, but [Mog] reports that most of the bugs and other issues were recently worked out or are being actively worked on by other experts in the field. If you remember these games from the arcade era of the 80s and early 90s, it might be time to grab an old CRT and fire this one up again.

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A Simple RP2040-Based Audio DSP Board

June 21, 2022 by 11 Comments

If you’re one of those people who got into building electronics for the purpose of making music, then this Raspberry Pi RP2040-based audio DSP project by [DatanoiseTV] might be of interest. Provided is a FreeRTOS template application for creating Eurorack compatible synthesizers, effects processors, and similar DSP-based audio widgets.

The hardware platform has the usual Eurorack connectivity, including MIDI in, Control Voltages (CV) and the usual 5V-compatible triggers. An audio output is provided to send the audio out to the system mixer or any other analog modules. Additionally, connections are provided for a rotary encoder, a few push buttons, and an OLED display to allow construction of a rudimentary user interface on the module, if that is required.

The application template is generic enough, however the project is intended to be used with the Vult DSP transcompiler. Vult is a high-level programming language designed to enable easy creation of audio synthesizers and similar, producing C++ code as an output of the compilation process. This is then wrapped up with the RTOS goodies (although you don’t actually need them) to drop onto the RP2040 in the usual way, via the handy USB-C port. So, if you’re looking to get into DSP-based Eurorack modules for your homebrew synth rack, this might be a good place to start.

Just like the RP2040 isn’t the most obvious choice for a DSP application, neither is the ESP32 for that matter, but who cares? many modern micros are more than capable of audio DSP these days, with or without the dedicated functionality.

Processing Audio With The RP2040

April 17, 2022 by 9 Comments

The Raspberry Pi, although first intended as an inexpensive single-board computer for use in education, is now ubiquitous in electronics communities. Its low price as well as Linux platform and accessible GPIO make it useful in many places outside the classroom. But, if you want to abandon the ease-of-use in favor of an even lower price, the Raspberry Pi foundation makes that possible as well with the RP2040 chip, commonly found on the Pico. [Jason] shows us one way to make use of this powerful chip by putting one in an audio digital signal processing board.

While development boards are available for this chip, [Jason] has opted instead for a custom PCB which he designed himself and includes an integrated headphone amplifier and 3.5 mm audio jacks. To do the actual DSP work, the RP2040 chip uses three 12-bit ADC channels and 16 controllable PWM channels. The platform is also equipped with the TLV320AIC3254 codec from Texas Instruments. With all of this put together, he has a functioning open-source platform he calls the DS-Pi.

[Jason] has built this as a platform for guitar effects and as a customizable guitar amp modeler, but with a platform that is Arduino-compatible and fairly easy to program it could be put to use for anything involving other types of music or audio processing, like this specialized MIDI-compatible guitar effects platform which is built around the same processor.

Active Pickguard Makes For A Great Guitar Mod

December 13, 2021 by 6 Comments

Much discussion goes on in the guitar world about the best hardware to use. Whether its pickups, how they’re positioned, or even the specific breed of wood on the fretboard, it’s all up for debate. [Eli Hughes] put much of that to one side, however, with his innovative “Active Pickguard” project.

The project reimagines the electronics of an electric guitar from the ground up. Instead of typical electromagnetic pickups, six individual piezo pickups are built into the bridge – one for each individual string. The outputs of these pickups is conditioned and then read by the analog-to-digital converter of a Freescale Kinetis K40. The DSP-capable chip can then be used to apply all manner of effects. [Eli] demonstrates the guitar providing an uncanny imitation of an acoustic guitar, before demonstrating jazz and overdrive tones as well.

The Kinetis chip also features touch-sensitive inputs, which [Eli] put to good use. All the hardware is built into a pickguard-shaped PCB, complete with touch controls for things like volume, tone, and choosing different DSP patches.

Unlike a regular guitar, this one needs a power supply, which it gets via a CAT 6 cable, in place of the usual 1/4″ guitar cable. The CAT 6 also carries audio out to a converter box which allows the audio to be output to a regular guitar amplifier.

It’s a neat build, and one that shows just how modern technology can reimagine a simple 20th-century instrument. DSP really is magic, after all. Video after the break.

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FIR Filters For Xilinx

May 18, 2021 by 7 Comments

Digital filters are always an interesting topic, and they are especially attractive with FPGAs. [Pabolo] has been working with them in a series of blog posts. The latest covers an 8th order FIR filter in Verilog.  He covers some math, which you can find in many places, but he also shows how an implementation maps to DSP slices in a device. Then to reduce the number of slices, he illustrates folding which trades delay time for slice usage.

Folding takes a multi-stage parallel multiplication and breaks it into fewer multiplications done over a longer period of time. This reuses slices to reduce the number required for high-order filters.

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Signal Conditioning Hack Chat This Wednesday

February 15, 2021 by 4 Comments

Join us on Wednesday, February 17 at noon Pacific for the Signal Conditioning Hack Chat with Jonathan Foote!

The real world is a messy place, because very little in it stays in a static state for very long. Things are always moving, vibrating, heating up or cooling down, speeding up or slowing down, or even changing in ways that defy easy description. But these changes describe the world, and understanding and controlling these changes requires sensors that can translate them into usable signals — “usable” being the key term.

Making a signal work for you usually requires some kind of signal processing — perhaps an amplifier to boost a weak signal from a strain gauge, or a driver for a thermocouple. Whatever the case, pulling a useful signal that represents a real-world process from the background noise of all the other signals going on around it can be challenging, as can engineering systems that can do the job in sometimes harsh environments. Drivers, filters, amplifiers, and transmitters must all work together to get the clearest picture of what’s going on in a system, lest bad data lead to bad decisions.

To help us understand the world of signal conditioning, Jonathan Foote will drop by the Hack Chat. You may remember Jonathan as the “recovering scientist” who did a great Remoticon talk on virtual modular synthesizers. It turns out that synths are just a sideline for Dr. Foote, who has a Ph.D. in Electrical Engineering and a ton of academic experience. He’s a bit of a Rennaissance man when it comes to areas of interest — machine learning, audio analysis, robotics, and of course, signal processing. He’ll share some insights on how to pull signals from the real world and put them to work.

join-hack-chatOur Hack Chats are live community events in the Hackaday.io Hack Chat group messaging. This week we’ll be sitting down on Wednesday, February 17 at 12:00 PM Pacific time. If time zones have you tied up, we have a handy time zone converter.

Click that speech bubble to the right, and you’ll be taken directly to the Hack Chat group on Hackaday.io. You don’t have to wait until Wednesday; join whenever you want and you can see what the community is talking about.

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SOUL Wants To Process Your Audio

January 29, 2021 by 14 Comments

Abstraction is the core of nearly all progress in computing. Unless you are fabricating your own semiconductors and drawing wire, we all create with building blocks ranging from components like CPUs, to operating system functions, to specialized libraries. Just as you wouldn’t want to spend your time deblocking disk records or rendering fonts for output devices, you probably shouldn’t have to think too much about audio data. While there are some powerful audio processing libraries out there, a new embeddable language called SOUL (SOUnd Language) is now in version 1.0 and wants to help you create efficient code for processing audio.

The goal of SOUL is to target a runtime that can run on CPUs, but is better on DSPs. The code aims to be secure and real time with no pointers, garbage collection, and other things that typically interfere with audio processing or security.

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