RFM69 to MQTT Gateway on the Super-Cheap

[Martin] is working on a RFM69-to-MQTT bridge device. If you’re at all interested in DIY home automation, this is going to be worth following. Why? When your home automation network gets big enough, you’re going to have to think seriously about how the different parts talk to each other. There are a number of ways to handle this messaging problem, but MQTT is certainly a contender.

MQTT is a “lightweight” publish-subscribe framework that’s aimed at machine-to-machine data sharing, and runs on top of a normal TCP/IP network. IBM has been a mover behind MQTT since the beginning, and now Amazon is using it too.

But most MQTT servers need a TCP/IP network, which pretty much means WiFi, and this can be a killer for remote sensors that you’d like to run on battery power, or with limited processing power. For these use cases, a low-power, simple sub-gigahertz radio module is a better choice than WiFi. But then how to do you get your low-power radios to speak to your MQTT devices?

That’s the point of [Martin]’s MQTT bridge. Previously he had built a sub-gig radio add-on for a Raspberry Pi, and let the Pi handle the networking. But it looks like there’s enough processing power in a lowly ESP8266 to handle the MQTT side of things (over WiFi, naturally). Which means that you could now connect your 868 MHz radio devices to MQTT for less than the cost of two pumpkin spice, double-pump lattes.

On the firmware side, [Martin] has enlisted the help of [Felix], who developed the Arduino-plus-RFM69 project, the Moteino. [Felix] has apparently ported his RFM69 library to the ESP8266. We’re dying to see this working.

For now, we’ve got some suggestive screenshots which hint at some LAN-exposed configuration screens. We’re especially interested in the RFM + MQTT debug console window, which should really help in figuring out what’s gone wrong in a system that spans two radio protocols.

The bottom line of all of this? Super-cheap, power-efficient RFM69-based radio nodes can talk with your sophisticated MQTT network. Keep your eyes on this project.

Act Now And Receive the Prong Saver For Only $0.00!

Well, actually, you can’t buy this. But for [TVmiller’s] latest project he decided to have some fun with the video — so he made an infomercial for it.

Called the Prong Saver, the device clips onto any appliance’s electrical cord to help prevent you from accidentally pulling too hard and bending the electrical prongs. It’s basically a cord-tension alarm. The question is — can you hear it over the vacuum cleaner?

And just because he could, it’s solar powered. Because why the heck not? He built it using scraps he found around the workshop. That included a solar powered LED key chain, a small piezo speaker, an eyebolt and a compression spring. Anyway, check out the commercial after the break. It had us in stitches.

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SprayPrinter Paints Your Wall, One Pixel At A Time

SprayPrinter is a neat idea. You download a cellphone app, point the camera at a wall, and sweep the wall with a spray can fitted with a (Bluetooth? WiFi?) remote-controlled valve. The phone knows where the nozzle is, and sprays a dot whenever it needs to “paint” the picture of your choosing on the wall.

sprayprinter-estonia-designboom-002-818x500While we’re not sure that we have the patience to paint our walls this way, it’s a cool effect. But even more, we love the idea of using the cellphone camera for location sensing. Many robotics applications do just this with an overhead camera.

Of course, we’d love more detail about how it’s done, but it’s not hard to guess that it’s either a bit of machine vision in the phone, or simpler still, that the spray-can housing has IR LEDs inside that the phone can lock onto. Indeed, the prototype version of the product shown here does look like it has an LED on the opposite side from the orange nozzle.

It wouldn’t be hard to take this to the next level, by adding enough IR LEDs that the camera in your phone can sense orientation as well as location. Heck, by measuring the distances between LEDs, you could probably even get a rough measure of depth. This could open up the use of different nozzles.

Thanks [Itay] for the tip! Some images courtesy SprayPrinter, via designboom.

 

Heat Duct Rover Explores Stink, Rescues Flashlight

It all started with a bad smell coming from the heat register. [CuddleBurrito] recalled a time when something stinky ended up in the ductwork of his folks’ house which ended up costing them big bucks to explore. The hacker mindset shies away from those expenditures and toward literally rolling your own solution to investigating the funk. In the process [CuddleBurrito] takes us on a journey into the bowels of his house.

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The Running Cat

Cats are great to have around, but they need exercise. If you’re not in a position to let the cat outdoors, you need to look to something else when kitty wakes up bored from her 23 hour nap. Cat playscapes are useful diversions, but this is the first time we’ve considered real exercise equipment. Let’s get our feline friends their exercise fix with a hamster-esque cat exercise wheel.

[bbarlowski]’s design is simple but very clever, and almost looks like something you’d find flat-packed at IKEA. Built of CNC-milled birch plywood, the wheel rims snap together like puzzle pieces while the floor has tabs that slot into the rims. The tension of the bent floor panels locks everything together and makes for a smart looking wheel. The video after the break shows [Kuna the Maine Coon cat] in action on the wheel, and outlines a few plans for expansion, including adding an Arduino to monitor kitty’s activity and control both an RGB LED strip for mood lighting and a cat treat dispenser for positive reinforcement of the exercise regimen.

The project mounted an unsuccessful campaign in March and they’ve made the DXF cutting files available for download. Of course if it’s too much plywood and not enough Arduino for you, just build the Arduspider to torture – err, entertain your cat.

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Automatic Cat Feeder Dispenses Noms, Wants Cheezburger

[Domiflichi] likes his cats, but not the drudgery of feeding them. So, like any good engineer, this simple problem became his next project: building an automatic cat feeder. Based on an Arduino, his creation beeps to let the cats know that it is dinnertime, then dispenses food into a number of bowls. There are also buttons for manual control. This lets him give individual cats a separate feeding. Rounding out the feature set, a DS1307 RTC tracks the feeding times.

One of the most interesting parts of his build is the transfer from breadboard to protoboard. This usually involves taking apart a working version, then putting it back together and trying to figure out why it doesn’t work anymore. [Domiflichi]’s problem (detailed in a follow-up post) was figuring out how to program the real-time clock module to set the time, because it looses the time when you disconnect the power. Rather than use the Arduino to program the RTC,  he used the battery backup feature of the RTC chip, programming it on his computer and then soldering it onto the board. He went on to remove the backup battery after the chip was in place. That’s a solution that will no doubt have many readers waving their fingers disapprovingly, but it worked.

It may seem overly complicated, but his project is worth checking out to see how he approached some of the engineering challenges. The food hoppers themselves are off-the-shelf cereal dispensers. We’ve seen other designs bootstrap this mechanism with 3D printed augers.

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Blacksmith Forge Made From the Bathroom Sink

The sweltering heat had finally moved on and Giant Tick season was coming to a close (not kidding, they are HUGE here), when I decided to fire up my hacked together blacksmith forge made out of an old bathroom sink and aquarium stand.

In the age-old formula I needed to supply an air source to a fuel to create enough heat to make iron malleable. I got the idea that this particular bathroom sink might be a good candidate for a fire bowl after I banged my shin with it and then cursed at it. It was clearly made of cast iron and as proof it was clearly unfazed by my tirade of words which I hope my son has learned from the Internet and not from listening to me remodel the bathroom.

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