The equipment used in professional radio and TV studios is both extremely high quality and very expensive indeed, and thus out of the reach of an experimenter. Happily as studios are refurbished there’s a steady supply of second-hand equipment which can be surprisingly cheap, but as [Nathan] found out with a Quartz audio router, comes with no control software. What’s to be done with what’s essentially a piece of junk? Remove its brain and replace it with one that can be controlled, of course!
On the PCB alongside a bank of switch matrices is an FPGA which does the heavy lifting. That’s “heavy” in a limited sense, because all it does is handle the chip select lines for the matrices and write data to their registers. This is a task that can be handled by a microcontroller, so in goes an Arduino Nano, which along with a few other board modifications delivers a serial-controlled studio router.
The interesting part for us in this project comes from a look at the date codes on the board, they’re from the early 2000s. This is (roughly) contemporary with the ATmega chip on the Arduino, so we’re curious as to why the designers saw fit to use an FPGA when the microcontrollers of the day were clearly up to the task for much less outlay. We suspect a touch of millennium-era price inflation, but we can’t be sure.
VFD displays are beloved for their eerie glow that sits somewhere just off what you’d call blue. [mircemk] used one of these displays to create an old-school VU meter that looks straight out of a 1970s laboratory.
The build uses an Arduino Nano as the brains of the operation, which uses its analog inputs to process incoming audio into decibel levels for display on a VU meter. It’s then charged with driving a GP1287 VFD display. Unlike some VFDs that have preset segments that can be illuminated or switched off, this is a fully graphical dot matrix display that can be driven as desired. Thus, when it’s not acting as a bar graph VU meter, it can also emulate old-school moving-needle meters. Though, it bears noting, the slow updates the Arduino makes to the display means it’s kind of like those dodgy skeumorphic music apps of the 16-bit era; i.e. it’s quite visually jerky.
Overall, it’s a neat project that demonstrates how to work with audio, microcontrollers, and displays all in one. We’ve featured other projects from [mircemk] before, too, almost all of which appear in the same blue and grey project boxes. Video after the break.
[Trent M. Wyatt]’s CPUVolt library provides a fast way to measure voltage using no external components, and no I/O pin. It only applies to certain microcontrollers, but he provides example Arduino code showing how handy this can be for battery-powered projects.
The usual way to measure VCC is simple, but has shortcomings.
The classical way to measure a system’s voltage is to connect one of your MCU’s ADC pins to a voltage divider made from a couple resistors. A simple calculation yields a reading of the system’s voltage, but this approach has two disadvantages: one is that it constantly consumes power, and the other is that it ties up a pin that you might want to use for something else.
There are ways to mitigate these issues, but it would be best to avoid them entirely. Microchip application note 2447 describes a method of doing exactly that, and that’s precisely what [Trent]’s Arduino library implements.
What happens in this method is one selects Vbg (a fixed internal voltage reference that is temperature-independent) as Vin, and selects Vcc as the ADC’s voltage reference. This is essentially backwards from how the ADC is normally used, but it requires no external hookup and is only a bit of calculation away from determining Vcc in millivolts. There is some non-linearity in the results, but for the purposes of measuring battery power in a system or deciding when to send a “low battery” signal, it’s an attractive solution.
Being an Arduino library, CPUVolt makes this idea very easy to use, but the concept and method is actually something we have seen before. If you’re interested in the low-level details, then check out our earlier coverage which goes into some detail on exactly what is going on, using an ATtiny84.
What is it about solenoids that makes people want to make music with them? Whatever it is, we hope that solenoids never stop inspiring people to make instruments like [CamsLab]’s copper pipe auto-glockenspiel.
At first, [CamsLab] thought of striking glasses of water, but didn’t like the temporary vibe of a setup like that. They also considered striking piano keys, but thought better of it when considering the extra clicking sound that the solenoids would make, plus it seemed needlessly complicated to execute. So [CamsLab] settled on copper pipes.
That in itself was a challenge as [CamsLab] had to figure out just the right lengths to cut each pipe in order to produce the desired pitch. Fortunately, they started with a modest 15-pipe glockenspiel as a proof of concept. However, the most challenging aspect of this project was figuring out how to mount the pipes so that they are close enough to the solenoids but not too close, and weren’t going to move over time. [CamsLab] settled on fishing line to suspend them with a 3D-printed frame mounted on extruded aluminium. The end result looks and sounds great, as you can hear in the video after the break.
It works like you’d probably expect — the light moves back and forth between the two players. Keep it in the green and you have a nice, gentle volley going. Let it hit your red LED and you’ve lost a point. But if you can push your button while your yellow LED is lit, the light speeds up tremendously until the next button press in the green.
Our only wish is that subsequent yellow-light button presses would make it speed up even more. But there are really just the two speeds with the current programming.
Inside the cool laser-cut box is an Arduino Uno and a 9V battery, plus a current-limiting resistor and the all-important buzzer. We like how [newsonator] wired up the LEDs to the Arduino by soldering them to a row of header pins and sticking that into the Arduino so it can be used in other projects down the line. We also like how [newsonator] shoved a couple of dowels through the box to ultimately support the two buttons.
Check out the intro video after the break for the overall details. The build is done over a few different short videos which follow.
‘Tis the season for gift giving, and what better to give than a newfound love for hacking, soldering, and blinkenlights? In order to spread cheer and education at the local hackerspace, [Tom Goff] created this festive tree circuit board that can either sit in a stand to be admired, or worn as jewelry. The resistors are even designed to look like candy canes hanging from the boughs.
The brains of this festive little tree is an ATmega328P, which you probably recognize as the microcontroller that powers the Arduino Uno. Although this circuit has none of the extra bits you’d find on an Uno, not even a crystal oscillator, it can still be programmed with Arduino and use the 8 MHz internal clock.
[Tom] has provided good, thorough instructions, especially for the sticky bit of setting up the IDE to program using the 8 MHz internal clock. So even if you’re nowhere near Norwich Hackerspace, you can join in the fun. Be sure to check out the video after the break, wherein [Tom] walks through designing the PCB using Inkscape and Fritzing.
[Lex] over at Computing: The Details loves to make fun projects. Recently, he’s created a hardware CPU monitor that allows him to see how well his PC is parallelizing compile tasks at a glance. The monitor is built from 14 analog meters, along with some WS2812 RGB LEDs.
Each meter represents a core on [Lex]’s CPU, while the final two meters show memory and swap usage. The meters themselves are low-cost 5 mA devices. Of course, the original milliamps legends wouldn’t do much good, so [Lex] designed and printed graduations that glue over the top. The RGB LED strip is positioned so two LEDs fit under each meter. The LEDs allow a splash of color to draw attention to the current state of the machine. The whole bank going red would sure get our attention!
The system is controlled by an Arduino Mega, with the meters driven using the PWM pins. The only extra part is a 1 K resistor. The Arduino wrangles the LEDs as well. Sadly [Lex] did not include his software. He did describe it though. Basically he’s using a Rust program to call systemstat, obtaining the current CPU utilization data in Linux. A bit of math converts this into pointer values and LED colors. The data is then sent via USB-serial to the Arduino Mega. The software savvy will say it’s pretty easy to replicate, but the hardware only hackers among us might need a bit of help.
This isn’t the first custom meter we’ve seen on Hackaday. Your author’s first project covered by Hackaday was for a meter created using an automotive gauge stepper motor. I didn’t include source code either – but only because [Guy Carpenter]’s Switec X25 library had me covered.
[mircemk] built a slick-looking LED tester with a couple handy functions built in. Not only can one select a target current to put through an LED, but by providing a target voltage, the system will automatically calculate the necessary series resistor. If for example the LED is destined for 14 V, this device will not only show how the LED looks at the chosen current, but will calculate the required resistor to get the same results on a 14 V system.
The buttons on the left control the target current and the voltage of the destination system. Once an LED is connected it will light up and the display indicates the LED’s forward voltage, the LED current, and the calculated series resistor value to obtain the same result at the selected target voltage. It’s a handy way to empirically dial in LED brightness values without needing to actually set up any particular test environment.
On the inside there’s little more than a handful of passive components, an Arduino, an LCD display, and a few buttons. This kind of tool reminds us of the highly clever component testers that hit the hobbyist scene years ago, showing what kind of advanced tricks a modern microcontroller is capable of with the right programming. (Here’s a look at how those work, if you’re interested in some deeper details.)
[mircemk] demonstrates his tool in the video, embedded below. We particularly like the attention he paid to the enclosure, giving it a very functional layout. It goes to show that when designing something, it’s never too early to consider enclosure and UI layout.
The piano has been around for a long time now. Not long after its invention, humans started contemplating how they could avoid playing it by getting a machine to do the job instead. [vicenzobit] is the latest to take on this task, building a “Robot Pianista” that uses a simple mechanism to play a tune under electronic command (Spanish language, Google Translate link).
An Arduino Nano is the heart of the build, paired with a shield that lets it run a number of servo motors. The servos, one per key, are each assembled into a 3D-printed bracket with a cam-driven rod assembly. When the servo turns, the cam turns, and pushes down a rod that presses the piano key.
The build is limited in the sense that you can only play as many keys as you have servo channels, but nonetheless, it does the job. With eight servos, it’s able to play a decent rendition of Ode to Joy at a steady tempo, and that’s an excellent start.
After helping tens of thousands of people get started with the world of electronics and Arduino-based microcontroller projects with the Arduino Workshop book, it was time to help and guide people further into more complex ideas and concepts that can enable a greater variety of possibilities.
Those who have worked through “Arduino Workshop” or a lesser book and are curious to learn more about what can be done with an Arduino or compatible board,
Anyone with some experience in electronics and coding, who is happy to skip into more intermediate topics straight away.
People who need a reference book for the wide variety of hardware and software tools described in the book,
You. Yes, you. Learning is for a lifetime, and you’re reading this – so why not continue with the world of electronics and microcontrollers? Or give a copy to someone who enjoys learning more about technology?
Arduino for Arduinians is printed using a convenient lie-flat technology, so you can have the book open to your side and not worry about the pages flapping about and losing your position while working on your projects. All the required code is included in the book, however you can also download them along with a list of parts and supplier information from the book’s website.
Anyone with a modicum of Arduino knowledge can use this book, and if you’re coming from a different microcontroller platform – I genuinely believe you can get started with this book as well.
In some of the chapters, the use of external circuitry is required for ease of assembly, and in these cases you can download gerber files to have your own PCBs manufactured by one of the many low-cost providers. A sample of the project prototype PCBs are shown below:
And unlike some other books, each and every project has been built and tested so you can be confident of finding success very quickly.
The 8-bit Arduino platform is still, in my opinion, an inexpensive and most approachable way of learning about electronics and microcontrollers – and opens up a whole new world of creativity or even the pathway to a career in technology. A copy of Arduino for Arduinianswill help the accomplished Arduino beginner continue with their journey.
To learn more about Arduino for Arduinians, you can review the table of contents, download a sample chapter, Arduino sketches and parts list and order copies for yourself and others from the No Starch Press online store. Orders from No Starch Press also include a free electronic copy so you can get started immediately.
You can also purchase copies from amazon, kindle, or your preferred bookseller.
If you are reading via Kindle on a PC – don’t copy and past the code from the Kindle reader. Instead, download the files from the book website.
