arduino

2932 Articles

Arduino + Ham Radio = Texting

November 19, 2021 by 12 Comments

Over on the Spectrum web site, [Dale] — a relatively new ham radio operator — talks about his system for sending text messaging over VHF radios called HamMessenger. Of course, hams send messages all the time using a variety of protocols, but [Dale] wanted a self-contained and portable unit with a keyboard, screen, and a GPS receiver. So he built one. You can find his work on GitHub.

At the heart of the project is MicroAPRS, an Arduino firmware for packet radio. Instead of using a bigger computer, he decided to dedicate another Arduino to do everything but the modem function.

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Run UNIX On Microcontrollers With PDP-11 Emulator

November 19, 2021 by 40 Comments

C and C++ are powerful tools, but not everyone has the patience (or enough semicolons) to use them all the time. For a lot of us, the preference is for something a little higher level than C. While Python is arguably more straightforward, sometimes the best choice is to work within a full-fledged operating system, even if it’s on a microcontroller. For that [Chloe Lunn] decided to port Unix to several popular microcontrollers.

This is an implementation of the PDP-11 minicomputer running a Unix-based operating system as  an emulator. The PDP-11 was a popular minicomputer platform from the ’70s until the early 90s, which influenced a lot of computer and operating system designs in its time. [Chloe]’s emulator runs on the SAMD51, SAMD21, Teensy 4.1, and any Arduino Mega and is also easily portable to any other microcontrollers. Right now it is able to boot and run Unix but is currently missing support for some interfaces and other hardware.

[Chloe] reports that performance on some of the less-capable microcontrollers is not great, but that it does run perfectly on the Teensy and the SAMD51. This isn’t the first time that someone has felt the need to port Unix to something small; we featured a build before which uses the same PDP-11 implementation on a 32-bit STM32 microcontroller.

Binaural Hearing Modeled With An Arduino

November 16, 2021 by 15 Comments

You don’t have two ears by accident. [Stoppi] has a great post about this, along with a video you can see below. (The text is in German, but that’s what translation is for.) The point to having two ears is that you receive audio information from slightly different angles and distances in each ear and your amazing brain can deduce a lot of spatial information from that data.

For the Arduino demonstration, cheap microphone boards take the place of your ears. A servo motor points to the direction of sound. This would be a good gimmick for a Halloween prop or a noise-sensitive security camera.

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Machine Learning Shushes Stressed Dogs

November 15, 2021 by 20 Comments

If there’s one demographic that has benefited from people being stuck at home during Covid lockdowns, it would be dogs. Having their humans around 24/7 meant more belly rubs, more table scraps, and more attention. Of course, for many dogs, especially those who found their homes during quarantine, this has led to attachment issues as their human counterparts have begin to return to work and school.

[Clairette] has had a particularly difficult time adapting to her friends leaving every day, but thankfully her human [Nathaniel Felleke] was able to come up with a clever solution. He trained a TinyML neural net to detect when she barked and used and Arduino to play a sound byte to sooth her. The sound bytes in question are recordings of [Nathaniel]’s mom either praising or scolding [Clairette], and as you can see from the video below, they seem to work quite well. To train the network, [Nathaniel] worked with several datasets to avoid overfitting, including one he created himself using actual recordings of barks and ambient sounds within his own house. He used Eon Tuner, a tool by Edge Impulse, to help find the best model to use and perform the training. He uploaded the trained network to an Arduino Nano 33 BLE Sense running Mbed OS, and a second Arduino handled playing sound bytes via an Adafruit Music Maker Featherwing.

While machine learning may sound like a bit of an extreme solution to curb your dog’s barking, it’s certainly innovative, and even appears to have been successful. Paired with this web-connected treat dispenser, you could keep a dog entertained for hours.

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Low-Cost Computer Gesture Control With An I2C Sensor

November 12, 2021 by 6 Comments

Controlling your computer with a wave of the hand seems like something from science fiction, and for good reason. From Minority Report to Iron Man, we’ve seen plenty of famous actors controlling their high-tech computer systems by wildly gesticulating in the air. Meanwhile, we’re all stuck using keyboards and mice like a bunch of chumps.

But it doesn’t have to be that way. As [Norbert Zare] demonstrates in his latest project, you can actually achieve some fairly impressive gesture control on your computer using a $10 USD PAJ7620U2 sensor. Well not just the sensor, of course. You need some way to convert the output from the I2C-enabled sensor into something your computer will understand, which is where the microcontroller comes in.

Looking through the provided source code, you can see just how easy it is to talk to the PAJ7620U2. With nothing more exotic than a switch case statement, [Norbert] is able to pick up on the gesture flags coming from the sensor. From there, it’s just a matter of using the Arduino Keyboard library to fire off the appropriate keycodes. If you’re looking to recreate this we’d go with a microcontroller that supports native USB, but technically this could be done on pretty much any Arduino. In fact, in this case he’s actually using the ATtiny85-based Digispark.

This actually isn’t the first time we’ve seen somebody use a similar sensor to pull off low-cost gesture control, but so far, none of these projects have really taken off. It seems like it works well enough in the video after the break, but looks can be deceiving. Have any Hackaday readers actually tried to use one of these modules for their day-to-day futuristic computing?

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Flip-Dot Oscilloscope Is Flippin’ Awesome

November 9, 2021 by 6 Comments

Oscilloscope displays have come a long way since the round phosphor-coated CRTs that adorned laboratories of old. Most modern scopes ship with huge, high-definition touch screens that, while beautiful, certainly lack a bit of the character that classic scopes brought to the bench. It’s a good thing that hackers like [bitluni] are around to help remedy this. His contribution takes the form of what may be both the world’s coolest and least useful oscilloscope: one with a flip-dot display.

Yup — a flip-dot display, in all it’s clickedy-clacky, 25×16 pixel glory. The scope can’t trigger, its maximum amplitude is only a couple of volts, and its refresh rate is, well, visible, but it looks incredible. The scope is controlled by an ESP32, which reads the analog signal being measured. It then displays the signal via an array of driver ICs, which allow it to update the dots one column at a time by powering the tiny electromagnets that flip over each colored panel.

Even better, [bitluni] live-streamed the entire build. That’s right, if you want to watch approximately 30 hours of video covering everything from first actuating a pixel on the display to designing and assembling a PCB to drive it, then you’re in luck. For the rest of us, he was kind enough to make a much shorter summary video you can watch below. Of course, this scope doesn’t run Doom like some others, but its probably only a matter of time.

Thank to [Zane Atkins] for the tip!

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Adafruit AVRProg Grows UPDI Interface Support

November 8, 2021 by 11 Comments

Making a small number of things with an embedded application is pretty straightforward, you usually simply plug in a programmer or debugger dongle (such as an AVRISP2) into your board with an appropriate adaptor cable, load your code into whatever IDE tool is appropriate for the device and hit the program button. But when you scale up a bit to hundreds or thousands of units, this way of working just won’t cut it. Add in any functional or defect-oriented testing you need, and you’re going to need a custom programming rig.

Adafruit have a fair bit of experience with building embedded boards and dealing with the appropriate testing and programming, and now they’ve updated their AVR Programming library to support the latest devices which have moved to the UPDI (Unified Programming and Debug Interface) programming interface. UPDI is a single-wire bidirectional asynchronous serial interface which enables programming and debugging of embedded applications on slew of the new AVR branded devices from Microchip. An example would be the AVR128DAxx which this scribe has been tinkering with lately because it is cheap, has excellent capacitive touch support, and is available in a prototype-friendly 28-pin SOIC package, making it easy peasy to solder.

The library is intended for use with the Arduino platform, so it should run on a vast array of hardware, without any special requirements, so making a custom programming jig out of hardware lots of us have lying around is not a huge hassle.

Adafruit provide a few application examples in the project GitHub to get you going, such as this ATTiny817 example that wipes the flash memory, sets appropriate fuses and drops in a bootloader.

The UPDI code was taken from the [brandanlane’s] portaprog which is hosted on the TTGO T-Display ESP32 board from Chinese outfit LilyGo, which is also worth checking out.

A little while ago we saw how the AVR Multitool, the AVRGPP learned to speak UPDI, and since we’re on programming interfaces, its possible to get the cheap-as-chips USBasp to speak TPI as well.

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