A Modern Solution To Tea Bag Inventory Management

Britain is famously known as a land of manners and hospitality. Few situations could make an Englishman’s stiff upper lip quiver, short of running out of tea bags while entertaining house guests. Thankfully, [The Gentleman Maker] is here and living up to his name – with a helpful tea monitor to ensure you’re never caught out again.

The Intelli-T, as it has been dubbed, monitors tea inventory by weight. An Arduino Uno combined with a HX711 IC monitors a load cell mounted under a canister, with a reed switch on the lid. Upon the canister being open and closed, the Arduino takes a measurement, determining whether tea stocks have dipped below critical levels. If the situation is dire, a Raspberry Pi connected over the serial port will sound an urgent warning to the occupants of the home. If there is adequate tea, the Raspberry Pi will instead provide a helpful tea fact to further educate the users about the hallowed beverage.

It’s a fun project, and one that has scope for further features, given the power of the Raspberry Pi. A little more work could arrange automatic ordering of more tea online, or send alerts through a service like IFTTT. We’ve seen [The Gentleman Maker]’s uniquely British hacks before, such as the umbrella that tells you the weather. Video after the break.

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Python Script Sends Each Speaker Its Own Sound File

When it comes to audio, the number of speakers you want is usually governed by the number of tracks or channels your signal has. One for mono, two for stereo, four for quadrophonic, five or more for surround sound and so on. But all of those speakers are essentially playing different tracks from a “single” audio signal. What if you wanted a single audio device to play eight different songs simultaneously, with each song being piped to its own speaker? That’s the job [Devon Bray] was tasked with by interdisciplinary artist [Sara Dittrich] for one of her “Giant Talking Ear” installation project. He built a device to play multiple sound files on multiple output devices using off the shelf hardware and software.

But maybe a hack like this could be useful in many applications other than just art installations. It could be used in an Escape room, where you may want the various audio streams to start in synchronicity at the same time, or as part of a DJ console, sending one stream to the speakers and another to the head phones, or a game where you have to run around a room full of speakers in the right sequence and speed to listen to a full sentence for clues.

His blog post lists links for the various pieces of hardware required, although all of it is pretty generic, and the github repository hosts the code. At the heart of the project is the Sounddevice library for python. The documentation for the library is sparse, so [Bray]’s instructions are handy. His code lets you “take a directory with .wav files named in numeric order and play them over USB sound devices attached to the host computer over and over forever, looping all files once the longest one finishes”. As a bonus, he shows how to load and play sound files automatically from an attached USB drive. This lets you swap out your playlist on the Raspberry Pi without having a use a keyboard/mouse, SSH or RDP.

Check the video after the break for a quick roundup of the project.

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Hack My House: Garage Door Cryptography Meets Raspberry Pi

Today’s story is one of victory and defeat, of mystery and adventure… It’s time to automate the garage door. Connecting the garage door to the internet was a must on my list of smart home features. Our opener has internet connection capabilities built-in. As you might guess, I’m very skeptical of connecting a device to the internet when I have no control over the software running on it.

The garage door is controlled by a button hung on the garage wall. There is only a pair of wires, so a simple relay should be all that is needed to simulate the button press from a Raspberry Pi. I wired a relay module to a GPIO on the Pi mounted in the garage ceiling, and wrote a quick and dirty test program in Python. Sure enough, the little relay was clicking happily– but the garage door wasn’t budging. Time to troubleshoot. Does the push button still work? *raises the garage door* yep. How about the relay now? *click…click* nope.

You may have figured out by now, but this garage door opener isn’t just a simple momentary contact push button. Yes, that’s a microcontroller, in a garage door button. This sort of scenario calls for forensic equipment more capable than a simple multimeter, and so I turned to Amazon for a USB oscilloscope that could do some limited signal analysis. A device with Linux support was a must, and Pico Technology fit the bill nicely.

Searching for a Secret We Don’t Actually Need

My 2 channel Picotech oscilloscope, the 2204A, finally arrived, and it was time to see what sort of alien technology was in this garage door opener. There are two leads to the button, a ground and a five volt line. When the button is pressed, the microcontroller sends data back over that line by pulling the 5 V line to ground. If this isn’t an implementation of Dallas 1-wire, it’s a very similar concept.

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Get Organized With This Raspberry Pi E-Ink Calendar

Like many hackers, we love e-ink. There’s something mesmerizing and decidedly futuristic about the way the images shift around and reconstitute themselves. Like something from Harry Potter, but that you can buy on Alibaba instead of from a shop in Diagon Alley. But as anyone who’s used the technology can tell you, the low refresh rate of an e-ink screen limits its potential applications. It works great for reading books, but beyond that its struggled to find its niche in a world of cheap LCDs.

But [Zonglin Li] has recently wrapped up a project which shows that e-ink has at least one more use case: personal calendars. You can get way with only updating the screen once a day so the refresh rate won’t matter, and the rest of the time it’s going to be static anyway so you might as well enjoy the energy savings of leaving the screen off. With a Raspberry Pi behind the scenes pulling data from the Internet, it can populate the calendar with everything from your personal schedule to when your favorite podcast drops.

In practice, [Zonglin] is actually updating the display every hour as he’s included the current weather conditions on the top left of the screen, but even still, this is a perfect application for the very unique properties of e-ink displays. The display is a 7.5 inch 640×384 model from Waveshare that retails for about $50 USD, so between the display, the Raspberry Pi, and something to put it all in (here, a picture frame) this is a pretty cheap build compared to some of the large format e-ink displays out there.

The software side is written in Python 3, and [Zonglin] has documented how others can easily plug in their own information so it can pull schedule data from Google Calendar and local conditions from Open Weather Map. The MIT licensed source code is also very well organized and commented, so this could serve as an excellent base if you’re looking to create a more comprehensive e-ink home information display.

If this seems a little too pedestrian for your tastes, you could always put together an e-ink movie player, a surprisingly functional Linux terminal, or a very slick ESP8266-based name tag. If you’ve got the better part of $1K USD and don’t know what to do with it, you could even get an e-ink license plate.

Hackaday Links: February 10, 2019

Last month was NAMM, the National Association of Musical Something that begins with ‘M’, which means we’re synthed and guitarded out for the year. The synth news? Behringer are making cheap reproductions and clones of vintage gear. There’s something you need to know about vintage gear: more than half of everything produced today has a Roland 808 or 909 drum machine (or sample), a 303 bass synth, or a 101 mono synth in it. Put an 808, 909, 303, and 101 on the same table, connected to a mixer, and you can make most of the electronic music from the ’80s and ’90s. And Behringer is cloning these synths. Neat times. But there’s a problem: Roland is trademarking these drum machines and synths, with trademark filings in the US and Germany. These are ‘trade dress’, or basically the beautiful red, orange, yellow, and white buttons of the 808 and the digital cyber silver plastic aesthetic of the 303, but there you go. It’s round one in the Roland v. Behringer match, may the first person to give me an 808, 909, 303, and 101 for a thousand dollars win.

Synths? Sure thing. Here’s a stash of New Old Stock 8580 SID chips, the ‘synth on a chip’ found in the Commodore 64. The price? $50. [ben] bought one of these, and the card that came with it said,  “We purchased these chips in 2006 and they’ve been stored in our climate-controlled storage area ever since. Even still, we found a handful of them that didn’t pass testing. Treat them with care!” Yes, a bunch of SID chips for sale is noteworthy, but at $50 a piece for 1980s technology, can someone explain why a chip fab isn’t cranking these things out? If there’s one ancient piece of silicon where the demand meets what it would cost to spin up the silicon line, the SID is it. Where are the modern reproductions?

Excited about making an electronic badge this year? Seeed is offering badge sponsorships for 2019, with an offer of a 5% discount on PCBA, and a 10% discount if you put the Seeed logo on the board. I might be a little biased, but Seeed is a place where you can just ask, “hey, you guys do clear soldermask?” and they find a way to do it.

The best way to tell if someone is rich isn’t by seeing if they have an i8 parked outside their mansion, or just a piece of junk with an M badge. It isn’t whether or not their filet mignon is wagyu or just Kobe, and it isn’t if they’re cruising the skies in a G650 or just puttering around in a Cessna Citation. No, the best way to tell if someone is rich is to notice their AirPods. Yes, Apple’s wireless headphones (which are actually pretty good!) are the best foundation of a class division these days. The best class signal since private railroad cars now has a problem: people are printing their own AirPods. [Brady32] over on Thingiverse has modeled AirPods, and now the design is being given away for free. The horror. Now anyone can print out their own little bits of white plastic, stick them in their ears, and tell the world, ‘I’m better than you. Don’t bother talking back, because I obviously can’t hear you.’

Raspberry Pi has a store! Yes, everyone’s favorite single board computer now has an ‘experimental space’ in Cambridge’s Grand Arcade. The Beeb is saying this store is ‘bucking the retail trend’, yes, but any retail trend doesn’t really apply here; brands have storefronts, and it’s not about revenue per square foot. Makerbot had a store, and it wasn’t about selling printers. Microsoft has stores. Sony built a mall to advertise the original PlayStation. While the Raspberry Pi brick and mortar store will probably never make any money, it is an indication the Raspberry Pi foundation has built a valuable brand worthy of celebration. Here’s some pics of the store itself.

Did you know Hackaday has a retro edition? It’s true! retro.hackaday.com is a lo-fi version of Hackaday without CSS or Javascript or any other cruft. It’s hand-written HTML (assembled by a script) of the first ten thousand or so Hackaday posts. The idea is that old computers could load the retro site, just to prove they could. [Matthias Koch] has an Atari PC3 — Atari’s PC compatible with an 8088 running at 8Mhz, 640k of RAM and a 20 MB hard drive — and got this thing to pull up the retro site. Good work!

What is the current state of 3D printing? What is the current state of 3D printing videos on YouTube? Oh boy we’re going to find out. [Potent Printables] did an ‘analysis’ of 3D printing videos published to YouTube, and found the category riddled with ‘clickbait’, without giving an operational definition of what ‘clickbait’ actually is, or how it’s different from any other content (because who would make a video that doesn’t have the purpose of attracting viewers) Anyway, there’s a problem with the YouTube algorithm, and 3D printing blogs are copying it, filling the entire hobby with disillusioned beginners, or something. After defining ‘The Most Viewed’ as not being a news or documentary footage (okay, that’s fair), having at least three printing videos, not clickbait, and gives the designer proper attribution, [Potent Printables] found a list filled with [Maker’s Muse], [3D Print Guy] and other channels who do 3D printing work, but don’t put 3D printing in the title. This is great; 3D printing isn’t a fascinating new technology that’s the first step towards Star Trek replicators; we’ve slid down the trough of disillusionment and now 3D printers are just tools. It’s great, and in 2018 things are as they should be.

So You Bought A Raspberry Pi Compute Module. What Now?

The Raspberry Pi Compute Module hasn’t seen as much attention as it should have in our community, probably because the equivalents from the familiar consumer range can be so much cheaper. When a Raspberry Pi Zero is a similar size to a Compute Module and costs so much less, we can’t blame you for asking what would be the point of using the industrial version.

It’s interesting then to see an Instructables piece from [Manolis Agkopian] in which he takes the reader through the process of creating their own Compute Module project. Following hot on the heels of the recent launch of the latest in the range it’s come to us at an appropriate moment to take a fresh look at the fruity computer’s more obscure incarnation. He starts with a description of the Compute Module and its official development board, before taking us through setting up a module and putting an OS on it. Finally he shows us his board design, which he offers us as a jumping-off point for our own projects.

So given that it’s piqued your interest, why might you want to design a Compute Module project? The answer’s simple enough: the consumer boards only provide the subset of features the Pi foundation people deemed appropriate for their mission. A Compute Module project is the equivalent of designing a Raspberry Pi that does it your way, tailored exactly for your needs. If you want an example, look no further than this stereoscopic camera.

Via Hacker News.

How To Time Drone Races Without Transponders

Drone racing is nifty as heck, and a need all races share is a way to track lap times. One way to do it is to use transponders attached to each racer, and use a receiver unit of some kind to clock them as they pass by. People have rolled their own transponder designs with some success, but the next step is ditching add-on transponders entirely, and that’s exactly what the Delta 5 Race Timer project does.

A sample Delta 5 Race Timer build (Source: ET Heli)

The open-sourced design has a clever approach. In drone racing, each aircraft is remotely piloted over a wireless video link. Since every drone in a race already requires a video transmitter and its own channel on which to broadcast, the idea is to use the video signal as the transponder. As a result, no external hardware needs to be added to the aircraft. The tradeoff is that using the video signal in this way is trickier than a purpose-made transponder, but the hardware to do it is economical, accessible, and the design is well documented on GitHub.

The hardware consists of RX508 RX5808 video receiver PCBs modified slightly to enable them to communicate over SPI. Each RX508 RX5808 is attached to its own Arduino, which takes care of low-level communications. The Arduinos are themselves connected to a Raspberry Pi over I2C, allowing the Pi high-level control over the receivers while it serves up a web-enabled user interface. As a bonus, the Pi can do much more than simply act as a fancy stopwatch. The races themselves can be entirely organized and run through the web interface. The system is useful enough that other projects using its framework have popped up, such as the RotorHazard project by [PropWashed] which uses the same hardware design.

While rolling one’s own transponders is a good solution for getting your race on, using the video transmission signal to avoid transponders entirely is super clever. The fact that it can be done with inexpensive, off the shelf hardware is just icing on the cake.