MIDI Mouse Makes Marvelous Music

July 18, 2021 by Adam Zeloof 5 Comments

It’s an old misconception that digital musicians just use a mouse and keyboard for their art. This is often far from the truth, as many computer music artists have a wide variety of keyboards/synths, MIDI controllers, and “analog” instruments that all get used in their creative process. But what if one of those instruments was just a mouse?

Well, that must have been what was going through [kzra]’s mind when he turned an old ps/2 roller ball mouse into an electronic instrument. Born out of a love for music and a hate for waste, the mouse is a fully functional MIDI controller. Note pitch is mapped to the x-coordinate of the pointer, and volume (known as velocity, in MIDI-speak) is mapped to the y-coordinate. The scroll wheel can be used as a mod wheel, user-configurable but most often used to vary the note’s pitch. The mouse buttons are used to play notes, and can behave slightly differently depending on the mode the instrument is set to.

Not satisfied with simply outputting MIDI notes, [kzra] also designed an intuitive user interface to go along with the mouse. A nice little OLED displays the mode, volume, note, and mouse coordinates, and an 8×8 LED matrix also indicates the note and volume. It’s a fantastic and versatile little instrument, and you’ve gotta check out the video after the break to see it for yourself. We’ve seen some awesome retro-tech MIDI controllers before, and this fits right in.

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Arduino Cable Tracer Helps Diagnose Broken USB Cables

July 18, 2021 by Lewin Day 31 Comments

We’ve all found ourselves swimming amongst too many similar-looking USB cables over the years. Some have all the conductors and functionality, some are weird power-only oddballs, and some charge our phones quickly while others don’t. It’s a huge headache and one that [TechKiwiGadgets] hopes to solve with the Arduino Cable Tracer.

The tracer works with USB-A, Mini-USB, Micro-USB, and USB-C cables to determine whether connections are broken or not and also to identify wiring configurations. It’s built around the Arduino Mega 2560, which is ideal for providing a huge amount of GPIO pins that are perfect for such a purpose. Probing results are displayed upon the 2.8″ TFT LCD display that makes it easy to figure out which cables do what.

It’s a tidy build, and one that we could imagine would be very useful for getting a quick go/no-go status on any cables dug out of a junk box somewhere. Just remember to WIDLARIZE any bad cables you find so they never trouble you again. Video after the break.

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PNG Image Decoding Library Does It With Minimal RAM

July 17, 2021 by Donald Papp 11 Comments

Want to display a PNG file on a display attached to an Arduino or other microcontroller board? You’ll want to look at [Larry Bank]’s PNGdec, the Arduino-friendly PNG decoder library which makes it much easier to work with PNG files on your chosen microcontroller.

The PNG image format supports useful features like lossless compression, and was generally developed as an improved (and non-patented) alternative to GIF files. So far so great, but it turns out that decoding PNG files on a microcontroller is a challenge due to the limited amount of memory compared to desktop machines. When the PNG specification was developed in the 90s, computers easily had megabytes of memory to work with, but microcontrollers tend to have memory measured in kilobytes, and lack high-level memory management. [Larry]’s library addresses these issues.

PNGdec is self-contained and free from external dependencies, and also has some features to make converting pixel formats for different display types easy. It will run on any microcontroller that can spare at least 48 K of RAM, so if that sounds useful then check out the GitHub repository for code and examples.

We’ve seen [Larry]’s wonderful work before on optimizing GIF playback as well as rapid JPEG decoding, and these libraries have increasing relevance as hobbyists continue to see small LCD and OLED-based displays become ever more accessible and affordable.

[PNG logo: PNG Home Site]

DIY PECS Board Uses Pictures To Communicate

July 15, 2021 by Kristina Panos 6 Comments

One way of communicating with autistic and non-verbal people is through the use of a Picture Exchange Communication System or PECS board, which they can use to point out what they need or want throughout the day. However, the commercial versions of these boards have their share of problems — they’re expensive, and they’re fairly rigid as far as the pictures go. [Alain Mauer] has created an open-source PECS board that is far more personalized, and has audio to boot.

The number one requisite here is sturdiness, as [Alain]’s son [Scott] has already smashed two smartphones and a tablet. [Alain] went with a laser-cut MDF enclosure that should last quite a while. Inside is an Arduino Pro Mini and a DF Player Mini that plays corresponding clips from a micro SD card whenever [Scott] presses a button on the 16-key copper foil capacitive keypad. This PECS board is smart, too — it will sound a turn-me-off reminder after a few minutes of inactivity, and issue audible low battery warnings.

So far, [Scott] is responding better to photographs of objects than to drawings. Watch him interact with the board after the break.

This is far from the first thing [Alain] has built to help [Scott]. Be sure to check out this Pi-based media player built to engage and not enrage. Continue reading “DIY PECS Board Uses Pictures To Communicate” →

Analog Style VU Meter With Arduino And OLED Display

July 14, 2021 by Tom Nardi 20 Comments

Looking for a digital recreation of the classic analog volume unit (VU) meter? If you’ve got an Arduino, a few passive components, and a SSD1306 OLED, then [mircemk] might have the answer for you. As you can see in the video below, his code turns a handful of cheap parts into an attractive and functional audio display.

The project’s Hackaday.IO page explains that the idea is based on the work of [stevenart], with code adapted for the SSD1306 display and some tweaks made to the circuit. While [mircemk] says the code could be modified for stereo as long as the two displays don’t have conflicting I2C addresses, he decided to simply duplicate the whole setup for each channel to keep things simple. With as cheap as some of these parts are nowadays, it’s hard to blame him.

[mircemk] has provided source code for a couple different styles of VU indicators, the colors of which can easily be inverted depending on your tastes. He also clarifies that the jerky motion of the virtual “needle” seen in the video is due to the camera; in real-life it sweeps smoothly like the genuine article.

Much like the project that aimed to recreate authentic “steam gauges” with e-paper displays, this as an excellent technique to file away for use in the future. Compared to authentic analog gauges, these digital recreations are quicker and faster to implement, plus going this route prevents any antique hardware from going on the chopping block.

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DIY Forth On Arduino

July 8, 2021 by Chris Lott 31 Comments

On a recent rainy afternoon, [Thanassis Tsiodras] decided to build his own Forth for the Arduino to relieve the boredom. One week of intense hacking later, he called it done and released his project as MiniForth on GitHub. [Thanassis] says he was inspired by our series of Forth articles from a few years back, and his goal was to build a Forth interpreter / compiler from scratch, put it into a Blue Pill microcontroller. That accomplished, he naturally decides to squeeze it into an Arduino Uno with only 2K of RAM.

Even if you are ambivalent about the Forth language, [Thanissis]’s project has some great ideas to check out. For example, he’s a big proponent of Makefile automation for repetitive tasks, and the project’s Makefile targets implements almost every task needed for development, building and testing his code.

Some development and testing tasks are easier to perform on the host computer. To that end, [Thanassis] tests his programs locally using the simavr simulator. The code is also portable, and he can compile it locally on the host and debug it using GDB along with Valgrind and AddressSanitizer to check for memory issues. He chose to write the program in C++ using only zero-cost abstractions, but found that compiling with the ArduinoSTL was too slow and used too much memory. No problem, [Thanassis] writes his own minimalist STL and implements several memory-saving hacks. As a final test, the Makefile can also execute a test suite of Forth commands, including a FizzBuzz algorithm, to check the resulting implementation.

Here’s a short video of MiniForth in action, blinking an LED on an UNO, and the video below the break shows each of the various Makefile tasks in operation. If you want to learn more, check out Elliot Williams’s Forth series which inspired [Thanassis] and this 2017 article discussing several different Forth implementations. Have you ever built your own compiler? Let us know in the comments below.

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Drink Water On Schedule Or Else Flood Your Desk

July 7, 2021 by Kristina Panos 47 Comments

How much water have you had to drink today? We would venture to guess that the answer is somewhere between ‘absolutely none’ and ‘not not nearly enough’. You can go ahead and blame poor work/life balance — that’s our plan, anyway — and just try to do better. All this working from home means the bathroom situation is now ideal, so why not drink as much water as you can?

But how? Well, you’re human, so you’ll need to make it as easy as possible to drink the water throughout the day. You could fill up one big jug and hoist it to your mouth all day long (or use a straw), but facing that amount of water all at once can be intimidating. The problem with using a regular-sized vessel is that you have to get up to refill it several times per day. When hyper-focus is winning the work/life tug-of-war, you can’t always just stop and go to the kitchen. What you need is an automatic water dispenser, and you need it right there on the desk.

[Javier Rengel]’s water pomodoro makes it as easy as setting your cup down in front of this machine and leaving it there between sips. As long as the IR sensor detects your cup, it will dispense water every hour. This means that if you don’t drink enough water throughout the day, you’re going to have it all over the desk at some point. [Javier] simply connected an Arduino UNO to a water pump and IR sensor pair and repurposed the milk dispenser from a coffee machine. Check it out in action after the break.

Of course, if you aren’t intimidated by the big jug approach, you could keep tabs on your intake with the right kind of straw.

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