NTC Thermistor To ThingSpeak Meter Makes A Great IoT Starter Project

December 20, 2022 by Donald Papp 5 Comments

There are a lot of IoT solutions and frameworks out there, and [Davide] demonstrates how to make a simple data logging and tracking application with his ESP8266-to-ThingSpeak project, which reads up to four NTC (negative temperature coefficient) thermistors and sends the data to ThinkSpeak over WiFi.

IoT can be a pretty deep rabbit hole, so if you’re looking for a simple project to demonstrate the working parts and provide a starting point, the project’s GitHub repository might help you get started. We’ve also seen ThingSpeak used to track toilet paper sheet usage, which is a nice demonstration of how to interface to a physical object with moving parts.

On the other hand, if you find reading NTC thermistors to be the more interesting part, you’re in luck because [Davide] has more information about that along with a modified ESP8266 Arduino library. Watch a tour of his temperature logging hardware in action in the video, embedded below.

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Fixing (And Improving!) An Annoying Apartment Entry System

December 11, 2022 by Donald Papp 7 Comments

[Zak]’s two-floor apartment has a typical door entry control system, but the setup is less than ideally convenient. The wall-mounted telephone-like intercom is downstairs, but [Zak] is usually upstairs. What’s an enterprising hacker to do? Obviously the most elegant solution is to simply do without visitors in the first place, but [Zak] opted for a more full-featured solution to the problem.

The layout of the typical wall-mounted door intercom is less than ideal.

He fixed things with a custom ESP8285-based board that, with the help of opto-isolation, allows him to detect visitors and grant entry without having to be physically present at the wall-mounted intercom. It’s even integrated into Telegram, and has a few neat new features. Let’s take a look.

The first interesting bit is how [Zak] rolled his own opto-isolation. The door entry system uses 14 VAC and is frankly — electromagnetically-speaking — a very noisy device. Attaching GPIO pins directly to this system from the ESP board for interfacing is not an option. The solution in situations like this is to use opto-isolation, so that interfaced devices can be electrically isolated from one another.

Rather than use off-the-shelf options, [Zak] opted to keep things small and economical by rolling his own solution using side-mounted IR LEDs on the small interface PCB. LEDs can also act as photodiodes, so by pointing two LEDs directly at one another and driving one LED from the door control system and measuring the small amount of resulting current on the other LED, [Zak] can detect states without having to directly connect a GPIO pin.

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Singapore Branches Out Into Internet Of Trees

December 8, 2022 by Kristina Panos 18 Comments

Five years ago, a 38-year-old woman was enjoying an outdoor concert with her family with one of her twin infants in her arms. In the week prior, it had been windy and rainy, but today, the weather was nice, and the concert was crowded. Without warning, a 270-year-old tembusu tree fell on the woman, pinning and ultimately killing her after the other concertgoers couldn’t remove it in time. This tragedy happened in spite of twice-yearly inspections where the tree showed no visual signs of trouble.

It’s exactly this type of incident that Singaporean officials hope to avoid by building an Internet of Trees. The equatorial island nation is home to roughly 5.5 million people, and around 7 million trees — about 6 million of which are tracked by Singapore’s National Parks Board, so that they can be managed remotely with an app. (The Board only tracks trees once they’ve reached a certain size, so we’ll assume that the other million are too young to join the fun just yet.)

While tree-triggered deaths are fairly few and far between, there are plenty of other ‘tree incidents’ that can occur, such as a branch falling, or a tree trunk snapping or uprooting. Depending on the size of the branch, this can be a dangerous nuisance as it could block roads, obscure signage, or destroy property. Thanks to the efforts of the National Parks Board, these incidents have dropped from around 3,000 per year at the turn of the millennium to under 500 per year today.

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A 3D printed cat treat dispenser on a table with a laptop in the background and with a treat in it's tray and a cat on the left about to eat the treat.

Local IOT Cat Treat Dispenser

November 22, 2022 by Abe Connelly 9 Comments

[MostElectronics], like many of us, loves cats, and so wanted to make an internet connected treat dispenser for their most beloved. The result is an ingenious 3D printed mechanism connected to a Raspberry Pi that’s able to serve treats through a locally run web application.

From the software side, the Raspberry Pi uses a RESTful API that one can connect to through a static IP. The API is implemented as a Python Flask application running under a stand alone web server Python script. The web application itself keeps track of the number of treats left and provides a simple interface to dispense treats at the operators leisure. The RpiMotorLib Python library is used to control a 28BYJ-48 stepper motor through its ULN2003 controller module, which is used to rotate the inside shaft of the treat dispenser.

The mechanism to dispense treats is a stacked, compartmentalized drum, with two drum layers for food compartments that turn to drop treats. The bottom drum dispenses treats through a chute connected to the tray for the cat, leaving an empty compartment that the top drum can replenish by dropping its treats into through a staggered opening. Each compartmentalized treat drum layer provides 11 treats, allowing for a total of 22 treats with two layers stacked on top of each other. One could imagine extending the treat dispenser to include more drum layers by adding even more layers.

Source code is available on GitHub and the STL files for the dispenser are available on Thingiverse. We’ve seen cat electronic feeders before, sometimes with escalating consequences that shake us to our core and leave us questioning our superiority.

Video after the break!

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Building A Local Network With LoRaWAN

October 22, 2022 by Bryan Cockfield 40 Comments

At its core, the Internet is really just a bunch of computers networked together. There’s no reason that there can’t be other separate networks of computers, or that we all have to tie every computer we have to The One Internet To Rule Them All. In fact, for a lot of embedded systems, it doesn’t make much sense to give them a full network stack and Cat6e Ethernet just to report a few details about themselves. Enter LoRaWAN, a wireless LAN that uses extremely low power for Internet-of-Things devices, and an implementation of one of these networks in an urban environment.

The core of the build is the LoRaWAN gateway which sits at the top of a tall building to maximize the wireless range of all of the other devices. It’s running ChirpStack on the software side and uses a Kerlink Wigrid station to broadcast. The reported range is a little over 9 km with this setup. Other gateways can also be added, and the individual LoRa modules can report to any available gateway. From there, the gateways all communicate back to the central server and the information can be sent out to the wider network, Internet or otherwise.

The project’s creator [mihai.cuciuc] notes that this sort of solution might not be best for everyone. There are other wide area networks available, but using LoRaWAN like this would be likely to scale better as more and more devices are added to the network. For some other ways that LoRa can be used to great effect, take a look at this project which builds an off-grid communications network with it.

Front Door Keys Hidden In Plain Sight

October 18, 2022 by Bryan Cockfield 27 Comments

If there’s one thing about managing a bunch of keys, whether they’re for RSA, SSH, or a car, it’s that large amounts of them can be a hassle. In fact, anything that makes life even a little bit simpler is a concept we often see projects built on to of, and keys are no different. This project, for example, eliminates the need to consciously carry a house key around by hiding it in a piece of jewelry.

This project sprang from [Maxime]’s previous project, which allowed the front door to be unlocked with a smartphone or tablet. This isn’t much better than carrying a key, since the valuable piece of electronics must be toted along in place of one. Instead, this build eschews the smartphone for a ring which can be worn and used to unlock the door with the wave of a hand. The ring contains an RFID which is read by an antenna that’s monitored by a Wemos D1 Mini. When it sees the ring, a set of servos unlocks the door.

The entire device is mounted on the front of the door about where a peephole would normally be, with the mechanical actuators on the inside. It seems just as secure (if not more so) than carrying around a metal key, and we also appreciate the aesthetic of circuit boards shown off in this way, rather than hidden inside an enclosure. It’s an interesting build that reminds us of some other unique ways of unlocking a door.

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Slap This Big Red Button For An Instant Social Media Detox

September 30, 2022 by Dan Maloney 8 Comments

Dangerous machines, like ones that can quickly reduce you to a fine red mist or a smoking cinder, tend to have a Big Red Button™ to immediately stop whatever the threat is. Well, if a more dangerous machine than social media has ever been invented, we’re not sure what it would be, which is why we’re glad this social media kill switch exists.

The idea behind [Gunter Froman]’s creation is to provide a physical interface to SocialsDetox, a service that blocks or throttles connectivity to certain apps and websites. SocialDetox blocks access using either DNS over HTTPS (DoH) or, for particularly pesky and addictive apps, a service-specific VPN. The service does require a subscription, the cost of which varies by the number of devices you want to protect, but the charges honestly seem pretty reasonable.

While SocialsDetox can be set up to block access on a regular schedule, say if you want to make the family dinner a social-free time, there may be occasions where killing social access needs to happen right now. This is where the Big Red Button comes into it, which is attached to a Wemos D1 Mini. Pressing the kill switch sends an API request to either enable or disable the service, giving you a likely much-needed break from the swirling vortex of hate and envy that we all can’t seem to live without. Except for Hackaday, of course — it’s totally not like that here.

The irony of using an IoT appliance to restrict access to social media is not lost on us, but you work with the tools you’ve got. And besides, we like the physical interface here, which sort of reminds us this fitting enclosure for a PiHole.