Tiny Motion Detection Alarm Does The Trick

If you have mischievous children or forgetful elderly in your life, you might want to build a couple of these tiny motion detection alarms to help keep them out of harm’s way. Maybe you want to keep yourself out of the cookie jar. We say good for you.

But you could always put one of these alarms on a window, a drawer, or anything else you don’t want opened or moved. The MPU6050 3-axis IMU makes sure that any way the chosen item gets jostled, that alarm is going off.

As you may have guessed, there isn’t much more to this build — the brain is a Seeed Xiao ESP32-C3, and there’s a buzzer, a battery, a switch, and a push button to program it.

The cool thing about using an ESP32-C3 is that [gokux] can use these for other things, like performing a task when motion is detected. If you do want to build yourself a couple of these, here are step-by-step instructions.

If you’d rather detect motion in the vicinity, here’s a PIR-based solution.

Machine Learning Baby Monitor, Part 2: Learning Sleep Patterns

The first lesson a new parent learns is that the second you think you’ve finally figured out your kid’s patterns — sleeping, eating, pooping, crying endlessly in the middle of the night for no apparent reason, whatever — the kid will change it. It’s the Uncertainty Principle of kids — the mere act of observing the pattern changes it, and you’re back at square one.

As immutable as this rule seems, [Caleb Olson] is convinced he can work around it with this over-engineered sleep pattern tracker. You may recall [Caleb]’s earlier attempts to automate certain aspects of parenthood, like this machine learning system to predict when baby is hungry; and yes, he’s also strangely obsessed with automating his dog’s bathroom habits. All that preliminary work put [Caleb] in a good position to analyze his son’s sleep patterns, which he did with the feed from their baby monitor camera and Google’s MediaPipe library.

This lets him look for how much the baby’s eyes are open, calculate with a wakefulness probability, and record the time he wakes up. This worked great right up until the wave function collapsed the baby suddenly started sleeping on his side, requiring the addition of a general motion detection function to compensate for the missing eyeball data. Check out the video below for more details, although the less said about the screaming, demon-possessed owl, the better.

The data [Caleb] has collected has helped him and his wife understand the little fellow’s sleep needs and fine-tune his cycles. There’s a web app, of course, and a really nice graphical representation of total time asleep and awake. No word on naps not taken in view of the camera, though — naps in the car are an absolute godsend for many parents. We suppose that could be curated manually, but wouldn’t doubt it if [Caleb] had a plan to cover that too.

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A Raspberry Pi 3 with a black Raspberry Pi Camera PCB on top of it, looking at the camera taking this picture. There's a Jolly Wrencher in the background.

Make Your Pi Moonlight As A Security Camera

A decade ago, I was learning Linux through building projects for my own needs. One of the projects was a DIY CCTV system based on a Linux box – specifically, a user-friendly all-in-one package for someone willing to pay for it. I stumbled upon Zoneminder, and those in the know, already can tell what happened – I’ll put it this way, I spent days trying to make it work, and my Linux skills at the time were not nearly enough. Cool software like Motion was available back then, but I wasn’t up to the task of rolling an entire system around it. That said, it wouldn’t be impossible, now, would it?

Five years later, I joined a hackerspace, and eventually found out that its CCTV cameras, while being quite visually prominent, stopped functioning a long time ago. At that point, I was in a position to do something about it, and I built an entire CCTV network around a software package called MotionEye. There’s a lot of value in having working CCTV cameras at a hackerspace – not only does a functioning system solve the “who made the mess that nobody admits to” problem, over the years it also helped us with things like locating safety interlock keys to a lasercutter that were removed during a reorganization, with their temporary location promptly forgotten.

Being able to use MotionEye to quickly create security cameras became quite handy very soon – when I needed it, I could make a simple camera to monitor my bicycle, verify that my neighbours didn’t forget to feed my pets as promised while I was away, and in a certain situation, I could even ensure mine and others’ physical safety with its help. How do you build a useful always-recording camera network in your house, hackerspace or other property? Here’s a simple and powerful software package I’d like to show you today, and it’s called MotionEye.

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Gesture Sensing With A Temperature Sensor

Good science fiction has sound scientific fact behind it and when Tony Stark first made his debut on the big screen with design tools that worked at the wave of a hand, makers and hackers were not far behind with DIY solutions. Over the years the ideas have become much more polished, as we can see with this Gesture Recognition with PIR sensors project.

The project uses the TPA81 8-pixel thermopile array which detects the change in heat levels from 8 adjacent points. An Arduino reads these temperature points over I2C and then a simple thresholding function is used to detect the movement of the fingers. These movements are then used to do a number of things including turn the volume up or down as shown in the image alongside.

The brilliant part is that the TPA81 8-Pixel sensor has been around for a number of years. It is a bit expensive though it has the ability to detect small thermal variations such as candle flames at up to 2 Meters. More recent parts such as the Panasonic AMG8834 that contain a grid of 8×8 such sensors are much more capable for your hacking/making pleasure, but come with an increased price tag.

This technique is not just limited to gestures, and can be used in Heat-Seeking Robots that can very well be trained to follow the cat around just to annoy it.

A Motion Sensing Light For Your Entrance Hallway

Arriving home to a dark house with an armful of anything is usually an exercise in fumbling confusion until someone manages to turn on a light. [Pavel Gesyuk] has circumvented this problem entirely by building and installing a motion detecting entrance light!

[Gesyuk] is using an Arduino clone by the name of  Funduino Mini Pro, a 2-channel, 2-way relay, — he only needed one, but you use what you have on hand — a recycled power supply to convert 220V AC to 5V DC, and an infrared sensor.

The project’s goal — in excess of a lighting solution for an entrance hallway — was the learn the ins and outs of the Arduino and motion sensors. After some initial hurdles familiarizing himself with the Arduino, [Gesyuk] wired everything together on a protoboard and stuck it in a plastic case — loose wires in a high traffic area doesn’t a safe home make.

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Hackaday Prize Entry: Automated Wildlife Recognition

Trail and wildlife cameras are commonly available nowadays, but the Wild Eye project aims to go beyond simply taking digital snapshots of critters. [Brenda Armour] uses a Raspberry Pi to not only take photos of wildlife who wander into the camera’s field of view, but to also automatically identify and categorize the animals seen using a visual recognition API from IBM via the Node-RED infrastructure. The result is a system that captures an image when motion is detected, sends the image to the visual recognition API, and attempts to identify any wildlife based on the returned data.

The visual recognition isn’t flawless, but a recent proof of concept shows promising results with crows, a cat, and a dog having been successfully identified. Perhaps when the project is ready to move deeper into the woods, elements from these solar-powered networked birdhouses (which also use the Raspberry Pi) could help cut some cords.

Hackaday Prize Entry: Magic Bit-Of-Wire Motion Detector Library For Arduino

We’re still not sure exactly how [connornishijima]’s motion detector works, though many readers offered plausible explanations in the comments the last time we covered it. It works well enough, though, and he’s gone and doubled down on the Arduino way and bundled it up nicely into a library.

In the previous article we covered [connor] demonstrating the motion detector. Something about the way the ADC circuit for the Arduino is wired up makes it work. The least likely theory so far involves life force, or more specifically, the Force… from Star Wars. The most likely theories are arguing between capacitance and electrostatic charge.

Either way, it was reliable enough a phenomenon that he put the promised time in and wrote a library. There’s even documentation on the GitHub. To initialize the library simply tell it which analog pin is hooked up, what the local AC frequency is (so its noise can be filtered out), and a final value that tells the Arduino how long to average values before reporting an event.

It seems to work well and might be fun to play with or wow the younger hackers in your life with your wizarding magics.