Wireless Protocol Reverse Engineered to Create Wrist Wearable Mouse

We’ve seen a few near-future sci-fi films recently where computers respond not just to touchscreen gestures but also to broad commands, like swiping a phone to throw its display onto a large flat panel display. It’s a nice metaphor, and if we’re going to see something like it soon, perhaps this wrist-mounted pointing device will be one way to get there.

The video below shows the finished product in action, with the cursor controlled by arm movements. Finger gestures that are very much like handling a real mouse’s buttons are interpreted as clicks. The wearable has a Nano, an MPU6050 IMU, and a nRF24L01 transceiver, all powered by some coin cells and tucked nicely into a 3D-printed case. To be honest, as cool as [Ronan Gaillard]’s wrist mouse is, the real story here is the reverse engineering he and his classmate did to pull this one off.

The road to the finished product was very interesting and more detail is shared in their final presentation (in French and heavy with memes). Our French is sufficient only to decipher “Le dongle Logitech,” but there are enough packet diagrams supporting into get the gist. They sniffed the packets going between a wireless keyboard and its dongle and figured out how to imitate mouse movements using an NRF24 module. Translating wrist and finger movements to cursor position via the 6-axis IMU involved some fairly fancy math, but it all seems to have worked in the end, and it makes for a very impressive project.

Is sniffing wireless packets in your future? Perhaps this guide to Wireshark and the nRF24L01 will prove useful.

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IoTP: The Internet of Toilet Paper

Our first impression of this IoT toilet paper roll was that somebody was pulling our leg. Watching the infomercial-esque video below is alternately hilarious and horrifying, but it leaves you with the unmistakable feeling that this is all a joke, and a pretty good one at that.  Right up until you get to the big Kimberly-Clark logo at the end, that is, and you realize that the international paper concern must be looking at this seriously.

When you read [zvizvi]’s Instructables post, you find out that this project is indeed a legitimate attempt to meld an Amazon Dash button with your toilet paper dispenser. For his proof-of-concept build, [zvizvi] started with a gag “talking TP” roll off eBay, designed to play back a voice clip when the paper is used. It had all the right guts, and being just the size for a Wemos Mini and an accelerometer for motion detection was a bonus. The smart spindle can tally the amount of paper used, so you’ll never be caught without a square to spare. And of course, critical TP usage parameters are uploaded to a cloud server, so that more toilet paper can be rushed to your door when you’re getting low.

The whole idea, including justification based on monitoring TP use as a proxy for bowel health, seems ridiculous, but we suspect there may be some brilliance here. Joke if you will, but in the end it’s probably better than an Internet of Farts.

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Hi-Tech Tool For Measuring Your Kid’s Height

Sure we can have our kids back up against a wall, force them to stand up straight, and use a ruler on their head to mark their height on the wall, but what kind of hacker would we be? There isn’t a single microcontroller or any electronic component involved! The DIY-family that calls themselves [HomeMadeGarbage] stood tall and came up with a high-tech tool to measure their kid’s height.

In place of the ruler they got a small wooden box to place on the head. Under the box, at the rear end facing down, they mounted a VL53L0X laser ranging sensor. With a range of 2 meters it’s sure to work with any child. But the box has to be sat level on the child’s head, otherwise the laser will be pointing down at an angle. To handle that they put an MPU6050 6-axis motion sensor in the box along with an Arduino Nano to tie it all together. A LCD display, measurement push-button and LED are mounted outside the box on the rear facing side.

To use it, a parent sits the box on the child’s head, making sure the laser sensor isn’t blocked and can see the floor. The LCD shows the height, along with the acceleration in the x and y directions. The LED is red if the box isn’t level and green if it is. Holding the measurement button pressed puts the tool in measurement mode and when it’s level, the LED turns blue and the LCD display freezes so you can make a note of the height. You’re good for a while, depending on your child’s age. See it being used to measure a child after the break as well as an additional clip showing what the output looks like when waving a hand up and down below it.

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Bewegungsfelder Is A Wireless IMU Motion Capturing System

For several years, hackers have been exploring inertial measurement units (IMUs) as cheap sensors for motion capturing. [Ivo Herzig’s] final Diploma project “Bewegungsfelder” takes the concept of IMU-based MoCap one step further with a freely configurable motion capturing system based on strap-on, WiFi-enabled IMU modules.

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Hypno-Jellyfish is Great for Kids (and Kids at Heart)


LED’s are fun. They are easily seen, not to hard to hook up, and produce a nice glow that can be gazed at for hours. Kids love them, so when [Jens] daughter was born, he knew that he wanted to create a device that would alternate colors depending on the object’s movement.

He utilized a mpu6050 accelerometer to detect changes in position, and wired together an Arduino Nano, a 9V battery, and a 12 LED neopixel ring from adafruit. Design requirements were jotted down beforehand ensuring that any child playing with the Hypno-Jellyfish would not be injured in any way. For example, anything that fits in a child’s mouth, will go in that child’s mouth; meaning that any materials used must be non-toxic, big enough not to be swallowed, and drool proof/water proof. The kids will pull, and throw, and drop the toy as well, so everything has to be of sturdy quality too. Epilepsy is also a concern when dealing with LED’s. But, [Jens] project hit the mark, making something that is kid-friendly while at the same time enjoyable for anyone else who likes color-changing lights.

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