Hacking An Arduino NFC Reader With WebUSB

January 1, 2020 by Al Williams 13 Comments

When [gdarchen] wanted to read some NFC tags, he went through several iterations. First, he tried an Electron application, and then a client-server architecture. But his final iteration was to make a standalone reader with an Arduino and use WebUSB to connect to the application on the PC.

This sounds easy, but there were quite a few tricks required to make it work. He had to hack the board to get the NFC reader’s interrupt connected correctly because he was using a Leonardo board. But the biggest problem was enabling WebUSB support. There’s a library, but you have to change over your Arduino to use USB 2.1. It turns out that’s not hard, but there’s a caveat: Once you make this change you will need the WebUSB library in all your programs or Windows will refuse to recognize the Arduino and you won’t be able to easily reprogram it.

Once you fix those things, the rest is pretty easy. The PC side uses node.js. If you back up a level in the GitHub repository, you can see the earlier non-Arduino versions of the code, as well.

If you want to understand all the logic that went into the design, the author also included a slide show that discusses the three versions and their pros and cons. He did mention that he wanted a short-range solution so barcodes and QR codes were out. He also decided against RFID but didn’t really say why.

NFC business cards are a thing. You can also use them to catch some public transportation.

Need Hackable Melodies? Here’s The TETRIS Theme And More

December 25, 2019 by Donald Papp 3 Comments

[Robson Couto] started to get interested in musical projects and as a side effect created downloadable code with simple notation for a good variety of themes, songs, and melodies. They are all for the Arduino and use only the built-in tone() function, but don’t let that distract you. If you look past that, you’ll see that each sketch is a melody that consists of single notes and durations; easily adapted to other purposes or simply used as-is. After all, [Robson] wanted the source of each tune to be easily understood, easily modified, and to have no external dependencies.

All that may sound a bit like MIDI, but MIDI has much more in common with hardware events than music notation because it includes (among other things) note starts and note ends as separate elements. Converting MIDI into a more usable format was a big part of a project that fed Bach music to a neural network and got surprisingly good results.

When doing music projects, sometimes having a recognizable melody represented very simply as notes and durations with only one note at a time can be an awfully handy resource, and you can find them on GitHub. There’s a brief video of the Tetris theme (actual name: Korobeiniki) being played after the break.

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Arduino Polygraph Shows How It’s Done

December 25, 2019 by Donald Papp 9 Comments

Sometimes, a project comes along that makes a good reference design for anyone doing similar work. In this particular case, it’s a DIY USB polygraph-like machine by [Juangg] using an Arduino and sensors on the hardware side, and a Python front end for data visualization. It’s even complete with 3D printed enclosure and sensor elements.

[Juangg] designed it to use three sensors: a pulse sensor, a breath sensor, and one to measure Galvanic Skin Response (GSR). The pulse sensor uses a piezo element pressed against a fingertip to detect changes in pressure resulting from blood flow. It can be picky about placement, but finding sweet spot can yield remarkably good readings. The breath sensor works on a similar principle but uses a 3D printed fixture to hold the sensor between a strap and the subject’s chest, so that breathing in and out can be detected. The GSR sensor is a voltage divider used to measure small changes in skin conductivity. How well does it all work? That depends on what one is looking to get out of it, but the documentation and design files are available from the project page and the GitHub repository if anyone wants a reference for similar work.

The polygraph may have a mixed reputation, but it makes a good project that demonstrates just how messy biometrics can be from an engineering perspective. And in case you missed it, here’s a reminder that Wonder Woman and the polygraph have much more in common than you might realize.

Minimalist Mate Maker Keeps You Caffeinated

December 24, 2019 by Kristina Panos 3 Comments

Americans love their coffee. The Brits adore their tea. In South America, the number one way to get through the day is with yerba mate, a tea made from the yerba plant. It is typically shared in a social setting, with one person preparing the beverage for everyone to enjoy. Although caffeine certainly deserves a ceremony, it never needs one. Hit the streets and you’ll see people everywhere with a thermos under one arm, keeping water hot and ready to refill the cup of mate in their hand.

The Stanley vacuum thermos is quite a popular choice for drinkers on the go, but the Argentinian government recently placed new restrictions foreign imports. [Roni Bandini] decided to build a minimum viable mate machine so he always has perfectly hot water on tap.

An Arduino Nano heats the water and displays the rising temperature on an LCD screen. When the temperature is just right, the display asks for your cup. An ultrasonic sensor detects the cup and dispenses a certain amount of water determined in the sketch. Yerba leaves can be used a few times before losing their flavor, so the machine keeps track and lets him know when it’s time to replace them. You can sip on a brief demo after the break.

Let’s say you don’t have perfectly-prepared mate, and it always comes out too hot. That’s better than too cold, but still not ideal. Why not make a temperature-sensing coaster that alerts you when it has cooled to perfection?

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Optical Communication Using LEDs Alone

December 22, 2019 by Jenny List 53 Comments

We’re all used to the humble LED as a ubiquitous source of light, but how many of us are aware that these components can also be used as photodiodes? It’s something [Giovanni Blu Mitolo] takes us through as he demonstrates a simple data link using just a pair of LEDs and a couple of Arduinos. It’s a showing off his PJON networking layer, and while you’d need a bit more than a couple of LEDs on breadboards for a real-world application, we still think it’s a neat demonstration.

PJON itself is very much worth a look, being an implementation of a robust and error-tolerant network for Arduinos and other small microcontroller platforms. It has a variety of communication strategies for various different media, and as this LED demonstration shows, its strength is that it’s capable of working through media that other networks would balk at. Whether it’s controlling home automation through metal heating ducts or providing an alternative to LoRa at 433 MHz, it’s definitely worth a second look. We’ve mentioned it before, but remain surprised that we haven’t seen it more often since. Take a look, the video is below the break.

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Programming Arduinos With Voice Commands

December 20, 2019 by Lewin Day 5 Comments

Programming is a valuable skill, though one that can be daunting to learn. Throw hardware in the mix, and things ratchet up another level again. However, there are many projects that have sought to reduce the level of difficulty for newcomers. HeyTeddy is a new project that allows users to program an Arduino with voice commands, and the help of on-screen tutorials.

It’s a system that initially sounds cumbersome, but through smart design, is actually quite streamlined. Users can talk to the system, which uses an Amazon Alexa device for natural language voice recognition. This enables HeyTeddy to respond to questions like “how do I use a flex sensor?” as well as direct commands, such as “Set pin 10 to 250”.

The demo video does a great job of demonstrating the system. While the system is not suited to professional development tasks, its has value as an educational tool for beginners. The system is able to guide users through both hardware setup on a breadboard, as well as guide them through tests when things don’t work. Once their experience level builds, code can be exported to the Arduino IDE for direct editing.

It’s a great tool that has plenty of promise to bring many more users into the hardware hacking fold. It’s out of the workshop of [MAKInteract], whose work we’ve seen before. Video after the break.

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Interactive Core Memory Shield Helps Explains The Past

December 19, 2019 by Gerrit Coetzee 9 Comments

[Andy Geppert] sends in his incredibly clever interactive core memory shield.

In a great display of one hacker’s work being the base for another’s, [Andy] started out with [Jussi Kilpelainen]’s core memory shield for Arduino. As he was playing with the shield he had a desire to “see” the core memory flipping and got the idea to add an LED matrix aligned behind the individual cores.

The first iteration worked, but it only showed the state that the Arduino believed the core memory to be in. What he really wanted was a live read on the actual state. He realized that an Adafruit Featherwing 8×8 matrix display also fits behind the core memory. Now the LEDs update based on the read state of the core memory. This allows him to flip the individual bits with a magnetic stylus and see the result. Very cool.

You can see a video of it working after the break.

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