There comes a point in every Arduino’s life where, if it’s lucky, it becomes a permanent fixture in a project. We can’t think of too many better forever homes for an Arduino than inside of a 3D-printed synthesizer such as this 17-key number by [ignargomez] et al.
While there are myriad ways to synthesizer, this one uses the tried-and-true method of FM synthesis courtesy of an Arduino Nano R3. In addition to the 17 keys, there are eight potentiometers here — four are used for FM synthesis control, and the other four are dedicated to attack/delay/sustain/release (ADSR) control of the sound envelope.
One of the interesting things here is that [ignargomez] and their team were short a few regular pots and modified a couple of slide pots for circular use — we wish there was more information on that. As a result, the 3D printed enclosure underwent several iterations. Be sure to check out the brief demo after the break.
Just before the holidays, we brought you word of the Arduboy Mini — the latest in the line of open source 8-bit handheld gaming systems designed by [Kevin Bates]. He was good enough to send along a prototype version ahead of the system’s Kickstarter campaign, and we came away impressed with the possibilities it offered for customization.
Today, we’re pleased to tell you that not only did the Arduboy Mini Kickstarter cross the finish line with more than six times its original funding goal, but [Kevin] has made some pretty major changes to the design from the last time it graced these pages. The final Mini offers even more opportunities for modification and expansion, while still keeping the $29 USD price tag which made it so appealing in the first place. Continue reading “New And Improved Arduboy Mini Smashes Funding Goal”→
Say, you’re starting your electronics journey with a few projects in mind. You have an ESP8266 board like the Wemos D1, a Li-Ion battery, you want to build a small battery-powered sensor that wakes up every few minutes to do something, and you don’t want to delve into hardware too much for now. Well then, does [Mads Chr. Olesen] have a tutorial for you! Here, you’ll learn the quick and easy way to get your sensor up and running, learn a few tricks for doing sleep Arduino environment, and even calculate how long your specific battery could last. Continue reading “Battery-Powered ESP8266 Sensor? Never Been Simpler”→
We’re all used to general purpose microcontroller boards such as the Arduino or its many imitators, but perhaps we don’t see as much of their industrial cousins. A programmable logic controller (PLC) is a computer designed to automate industrial machinery, and comes with protected interfaces and usually a specific PLC programming environment. Thus [Galopago]’s work with an inexpensive Chinese PLC clone is especially interesting, providing a route forward to using it within the Arduino IDE ecosystem.
Opening it up, the processor is identified as an STM32F103, and the connection needed to place it in bootloader mode is identified. Then it can be programmed from the Arduino IDE, even though its bootloader can’t be changed. Then to complete the process it’s necessary to identify the various different inputs and outputs by old-fashioned hardware reverse engineering.
This PLC may not be quite as robust as some products costing much more money, but it still represents a cost-effective way to access a microcontroller board with much of the interface circuitry already installed that would normally be required for controlling machinery. We expect that we’ll be seeing it appear on these pages over the coming months, and perhaps there might even be another comparison in the air.
[Wentworthm] couldn’t say no to his son’s plea for a Sonic the Hedgehog costume for Halloween but also couldn’t resist sprucing it up with LEDs either. The end result is a surprisingly cool light up Sonic the Hedgehog costume.
After some experimentation, [Wentworthm] ordered two costumes and ended up mixing and matching the head piece of one with the body suit of the other. For the head, [Wentworthm] created six 3D printed “quills” that had slots for the WS2812B LED strips to slide into and diffuse out the sides, with each quill sliding into the folds of the Sonic head “spikes”. Sewn strips of cloth were used to house the LED strips that were placed down the sides of the costume. An additional 3D printed switch housing was created to allow for a more robust interface to the two push buttons to activate the LEDs. An Arduino Nano, soldered to a protoboard, was used to drive the LED strips with a USB battery pack powering the whole project.
[Wentworthm] goes into more detail about the trials and errors, so the post is definitely worth checking out for more detail on the build. Halloween is always a great source of cool costumes and we’ve featured some great ones before, like a light up crosswalk costume to making a giant Gameboy colour costume.
For those unfamiliar with the details of the expansive work of fiction of Harry Potter, it did introduce a few ideas that have really stuck in the collective conscious. Besides containing one of the few instances of time travel done properly and introducing a fairly comprehensive magical physics system, the one thing specifically that seems to have had the most impact around here is the Weasley family clock, which shows the location of several of the characters. We’ve seen these built before in non-magical ways, but this latest build seeks to drop the price tag on one substantially.
To do this, the build relies on several low-cost cloud computing solutions and smartphone apps to solve the location-finding problem. The app is called OwnTracks and is an open-source location tracker which can report data to any of a number of services. [Simon] sends the MQTT data to a cloud-based solution called HiveMQCloud, but you could send it anywhere in principle. With the location tracking handled, he turns to some very low-cost Arduinos to control the stepper motors which point the clock hands to the correct locations on the face.
While the build does rely on a 3D printer for some of the internal workings of the clock, this does bring the cost down substantially when compared to other options. Especially when compared to this Weasley family clock which was built into a much larger piece of timekeeping equipment, having an option for a lower-cost location-tracking clock face like this one is certainly welcome.
An interesting aspect of time-varying waveforms is that by using a trick called a Fourier Transform (FT), they can be represented as the sum of their underlying frequencies. This mathematical insight is extremely helpful when processing signals digitally, and allows a simpler way to implement frequency-dependent filtration in a digital system. [klafyvel] needed this capability for a project, so started researching the best method that would fit into an Arduino Uno. In an effort to understand exactly what was going on they have significantly improved on the code size, execution time and accuracy of the previous crown-wearer.
A complete real-time Fourier Transform is a resource-heavy operation that needs more than an Arduino Uno can offer, so faster approximations have been developed over the years that exchange absolute precision for speed and size. These are known as Fast Fourier Transforms (FFTs). [klafyvel] set upon diving deep into the mathematics involved, as well as some low-level programming techniques to figure out if the trade-offs offered in the existing solutions had been optimized. The results are impressive.
Benchmarking results showing speed of implementation versus the competition (ApproxFFT)
Not content with producing one new award-winning algorithm, what is documented on the blog is a masterclass in really understanding a problem and there are no less than four algorithms to choose from depending on how you rank the importance of execution speed, accuracy, code size or array size.
Along the way, we are treated to some great diversions into how to approximate floats by their exponents (French text), how to control, program and gather data from an Arduino using Julia, how to massively improve the speed of the code by using trigonometric identities and how to deal with overflows when the variables get too large. There is a lot to digest in here, but the explanations are very clear and peppered with code snippets to make it easier and if you have the time to read through, you’re sure to learn a lot! The code is on GitHub here.
If you’re interested in FFTs, we’ve seen them before around these parts. Fill your boots with this link of tagged projects.
