An Arduino And A CD-ROM Drive Makes A CD Player

January 3, 2021 by Jenny List 49 Comments

In an age of streaming media it’s easy to forget the audio CD, but they still remain as a physical format from the days when the “Play” button was not yet the “Pay” button. A CD player may no longer be the prized possession it once was, but it’s still possible to dabble in the world of 120 mm polycarbonate discs if you have a fancy for it. It’s something [Daniel1111] has done with his Arduino CD player, which uses the little microcontroller board to control a CD-ROM drive via its IDE bus.

The project draws heavily from the work of previous experimenters, notably ATAPIDUINO, but it extends them by taking its audio from the drive’s S/PDIF output. A port expander drives the IDE interface, while a Cirrus Logic WM8805 S/PDIF transceiver handles the digital audio and converts it to an I²S stream. That in turn is fed to a Texas Instruments PCM5102 DAC, which provides a line-level audio output. All the code and schematic can be found in a GitHub repository.

To anyone who worked in the CD-ROM business back in the 1990s this project presses quite a few buttons, though perhaps not enough to dig out all those CDs again. It would be interesting to see whether the I²S stream could be lifted from inside the drive directly, or even if the audio data could be received via the IDE bus. If you’d like to know a bit more about I²S , we have an article for you.

Ambience Lamp Ripples Like Water

December 31, 2020 by Kristina Panos 14 Comments

After the year humanity has endured, we could all use a little more relaxation in our lives. This atmosphere lamp is just the thing to set a relaxing ambience for work, studying, or hanging out. Just touch the surface and the light ripples to life, resembling the concentric circles that form on the surface of still water when it is touched. When the light settles, it looks like an inviting pool that’s ready for a nighttime swim.

There aren’t really any surprises inside — the lamp is operated via capsense by touching the center of the top. Three NeoPixel rings and an RGB LED strip provide the lighting, and an Arduino UNO runs the show. [Qttting_F] used an inexpensive ceramic bowl with a piece of acrylic for a lid, but this could just as easily be printed in white PLA or something. Check it out in action after the break.

Ambience is nice, but sometimes you need something more functional. Those types of lamps can be printed, too.

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Co41D 2020 MIDI Theremin Sounds Pretty Sick

December 28, 2020 by Kristina Panos 4 Comments

As the pandemic rages on, so does the desire to spend the idle hours tinkering. [knaylor1] spent the second UK lockdown making a sweet Theremin-inspired noise machine with a low parts count that looks like a ton of fun.

It works like this: either shine some light on the photocells, cover them up, or find some middle ground between the two. No matter what you do, you’re going to get cool sounds out of this thing.

The photocells behave like potentiometers that are set up in a voltage divider. An Arduino UNO takes readings in from the photocells, does some MIDI math, and sends the serial data to a program called Hairless MIDI, which in turn sends it to Ableton live.

[knaylor1] is using a plugin called TAL Noisemaker on top of that to produce the dulcet acid house tones that you can hear in the video after the break.

If you’ve never played with light-dependent resistors before, do yourself a favor and spend a little bit of that Christmas cash on a variety pack of these things. You don’t even need an Arduino to make noise, you can use them as the pots in an Atari Punk console or make farty square waves with a hex inverting oscillator chip like the CD40106. Our own [Elliot Williams] once devoted an entire column to making chiptunes.

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76-bit Trombones Led By The Big MIDI File

December 27, 2020 by Matthew Carlson 30 Comments

Inspired by the creative genius of Martin Molin of Wintergatan fame, [iSax] set out to create a robotic MIDI-controlled trombone. It takes years for humans to develop the control and technique required to play the trombone well as the tone produced into the mouthpiece (embouchure) is a tricky combination of air pressure, lip tension, airflow, resonance in the mouth, and other sources of complex pressure.

[iSax] gives a thorough walkthrough of the machine, which is powered by two separate sources of air, one for the position of the slide and the other for producing sound. A potentiometer provides feedback on the position of the slide and a servo controls the flow rate into the silicone resonance chamber. The chamber can be tuned via a stepper motor that applies pressure, slightly altering the chamber’s frequency and pressure. An Arduino with Firmata allows the device to controlled easily from any host computer. A detailed writeup in PDF form is on the Hackday.io project page.

As you can imagine, simulating a human mouth is a daunting task and the number of variables meant that [iSax] ended up with something only vaguely trombone-like. While ultimately it didn’t turn out to be the astounding music machine that [iSax] hoped, it did end up being a fun feat of engineering we can appreciate and admire. Progress towards automatic brass instruments seems to be coming slowly as we saw similar results with this robotic trumpet. Maybe someday we’ll have robot brass sections, but not today.

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Discrete LEDs Make A Micro Display

December 24, 2020 by Kerry Scharfglass 5 Comments

Few things excite a Hackaday staff member more than a glowing LED, so it should be no surprise that combining them together into a matrix really gets us going. Make that matrix tiny, addressable, and chainable and you know it’ll be a hit at the virtual water cooler. We’ve seen [tinyledmatrix]’s work before but he’s back with the COPXIE, a pair of tiny addressable displays on one PCBA.

The sample boards seen at top are a particularly eye catching combination of OSH Park After Dark PCB and mysterious purple SMT LEDs that really explain the entire premise. Each PCBA holds two groups of discrete LEDs each arranged into a 5×7 display. There’s enough density here for a full Latin character set and simple icons and graphics, so there should be enough flexibility for all the NTP-synced desk clocks and train timetables a temporally obsessed hacker could want.

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4-bit Retrocomputer Emulator Gets Custom PCB

December 23, 2020 by Moritz v. Sivers 4 Comments

It might be fair to suspect that most people who are considered digital natives have very little to no clue about what is actually going on inside their smartphones, tablets, and computers. To be fair, it is not easy to understand how modern CPUs work but this was different at the beginning of the 80s when personal computers just started to become popular. People who grew up back then might have a much better understanding of computer basics thanks to computer education systems. The Busch 2090 Microtronic Computer System released in 1981 in Germany was one of these devices teaching people the basics of programming and machine language. It was also [Michael Wessel]’s first computer and even though he is still in proud possession of the original he just recently recreated it using an Arduino.

The original Microtronic was sold under the catchy slogan “Hobby of the future which has already begun!” Of course, the specs of the 4-bit, 500 kHz TMS 1600 inside the Microtronic seem laughable compared to modern microcontrollers, but it did run a virtual environment that taught more than the native assembly. He points out though that the instruction manual was exceptionally well written and is still highly effective in teaching students the basics of computer programming.

Already, a couple of years back he wrote an Arduino-based Microtronic emulator. In his new project, he got around to extending the functionality and creating a custom PCB for the device. The whole thing is based on ATMega 2560 Pro Mini including an SD card module for file storage, an LCD display, and a whole bunch of pushbuttons. He also added an RTC module and a speaker to recreate some of the original functions like programming a digital clock or composing melodies. The device can also serve as an emulator of the cassette interface of the original Microtronic that allowed to save programs with a whopping data rate of 14 baud.

He has certainly done a great job of preserving this beautiful piece of retro-tech for the future. Instead of an Arduino, retro computers can also be emulated on an FPGA or just take the original hardware and extend it with a Raspberry Pi.

A Tiny LED Matrix Is Better With Friends

December 23, 2020 by Kerry Scharfglass 8 Comments

When we last heard from [lixielabs] he was building Nixie tube replacements out of etched acrylic and LEDs. Well he’s moved forward a few decades to bring us the Pixie, a chainable, addressable backpack for tiny LED matrix displays.

Each Pixie module is designed to host two gorgeous little Lite-On LTP-305G/HR 5×7 LED dot matrix displays, which we suspect have been impulse purchases in many a shopping cart. Along with the displays there is a small matrix controller and an ATTINY45 to expose a friendly electrical interface. Each module is designed to be mounted edge to edge and daisy chained out to 12 or more (with two displays each) for a flexible display any size you need. But to address the entire array only two control pins are required (data and clock).

[lixielabs] has done the legwork to make using those pins as easy as possible. He is careful to point out the importance of a good SDK and provides handy Arduino libraries for common microcontrollers and a reference implementation for the Raspberry Pi that should be easy to crib from to support new platforms. To go with that library support is superb documentation in the form of a datasheet (complete with dimensions and schematic!) and well stocked GitHub repo with examples and more.

To get a sense of their graphical capabilities, check out a video of 6 Pixie’s acting as a VU meter after the break. The Pixie looks like what you get when a hacker gets frustrated at reinventing LED dot matrix control for every project and decided to solve it once and for all. The design is clean, well documented, and extremely functional. We’re excited to see what comes next! Continue reading “A Tiny LED Matrix Is Better With Friends” →