android

353 Articles

Metal Detector Gets Help From Smartphone

June 27, 2022 by 15 Comments

[mircemk] is quite a wizard when it comes to using coils of wires in projects, especially when their application is within easy-to-build metal detectors. There are all kinds of ways to send signals through coiled wire to detect metal objects in the ground, and today [mircemk] is demonstrating a new method he is experimenting with which uses a smartphone to detect the frequency changes generated by the metal detector.

Like other metal detectors, this one uses two coils of wire with an oscillator circuit and some transistors. The unique part of this build, though, is how the detector alerts the user to a piece of metal. Normally there would be an audible alert as the frequencies of the circuit change when in the presence of metal, but this one uses a smartphone to analyze the frequency information instead. The circuit is fed directly into the headphone jack on the smartphone and can be calibrated and used from within an Android app.

Not only can this build detect metal, but it can discriminate between different types of metal. [mircemk] notes that since this was just for experimentation, it needs to be calibrated often and isn’t as sensitive as others he’s built in the past. Of course this build also presumes that your phone still has a headphone jack, but we won’t dig up that can of worms for this feature. Instead, we’ll point out that [mircemk] has shown off other builds that don’t require any external hardware to uncover buried treasure.

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An Off-Grid Makeshift Cell Network

February 21, 2022 by 51 Comments

When traveling into the wilderness with a group of people, it’s good to have a method of communications set up both for safety and practicality. In the past people often relied on radios like FRS, CB, or ham bands if they had licenses, but nowadays almost everyone has a built-in communications device in their pocket that’s ready to use. Rather than have all of his friends grab a CB to put in their vehicle for their adventures together, [Keegan] built an off-grid network which allows any Android phone to communicate with text even if a cell network isn’t available.

The communications system is built on the LoRa communications standard for increased range over other methods like WiFi using a SX1278 chip and an ESP8266. The hardware claims a 10 km radius using this method which is more than enough for [Keegan]’s needs. Actually connecting to the network is only half of the solution though; the devices will still need a method of communication. For that, a custom Android app was created which allows up to 8 devices to connect to the network and exchange text messages with each other similar to a group text message.

For off-grid adventures a solution like this is an elegant solution to a communications problem. It uses mostly existing hardware since everyone carries their own phones already, plus the LoRa standard means that even the ESP8266 base station and transmitter are using only a tiny bit of what is likely battery power. If you’re new to this wireless communications method, we recently featured a LoRa tutorial as well.

Smart Ruler Has Many Features

December 2, 2021 by 12 Comments

For those of us who remember old ball mice, they were a lot like modern optical mice except that they needed to be cleaned constantly. Having optical mice as a standard way of interacting with a computer is a major improvement over previous eras in computing. With extinction of the ball mouse, there are an uncountable number of cheap optical mice around now which are easy pickings for modern hacking, and this latest project from [Vipul] shows off some of the ways that optical mice can be repurposed by building a digital ruler.

The build seems straightforward on the surface. As the ruler is passed over a surface the device keeps track of exactly how far it has moved, making it an effective and very accurate ruler. To built it, the optical component of a mouse was scavenged and mated directly to a Raspberry Pi Zero W over USB. Originally he intended to use an ESP32 but could not get the USB interface to work. [Vipul] was then able to write some software which can read the information from the mouse’s PCB directly and translate it into human-readable form where it is displayed on a small screen. The entire device is housed in a custom 3D-printed enclosure to wrap everything up, but the build doesn’t stop there though. [Vipul] also leveraged the Bluetooth functionality of the Pi and wrote a smartphone app which can be used to control the ruler as well.

While the device does have some limitations in that it has to make contact with the object being measured across its entire length, there are some situations where we can imagine something like this being extremely useful especially when measuring things that aren’t a straight line. [Vipul] has also made all of the code for this project publicly available for those of us who might have other uses in mind for something like this. We’ve seen optical mice repurposed for all kinds of things in the past, too, including measuring travel distances in autonomous vehicles.

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Want Octoprint But Lack A Raspberry Pi? Use An Old Android Phone

November 27, 2021 by 21 Comments

3D printers and Octoprint have a long history together, and pre-built images for the Raspberry Pi make getting up and running pretty easy. But there’s also another easy way to get in on the Octoprint action, and that’s to run it on an Android phone with the octo4a project.

A modern smartphone has a lot of useful features that make it attractive as an Octoprint host. There is a built-in touchscreen, easy power management, a built-in camera, and the fact that people regularly upgrade to new phones means that older Android phones — still powerful pieces of hardware in their own right — are readily available at low cost. The project is still relatively new, so don’t forget to check the Octoprint community thread for this project if you give it a try.

If you are wondering what Octoprint is and what it brings to the table, our own Tom Nardi explained what it does and why it matters when he shared his own upgrade experience from 2018. A few details are no longer current — for example one is no longer likely to encounter a Printrbot — but it’s still a perfectly valid primer on adding great management functionality to a 3D printer.

Hackaday Podcast 146: Dueling Trackballs, Next Level BEAM Robot, Take Control Of Your Bench, And Green Programming

November 26, 2021 by 3 Comments

Postpone your holiday shopping and spend some quality time with editors Mike Szczys and Elliot Williams as they sift through the week in Hackaday. Which programming language is the greenest? How many trackballs can a mouse possibly have? And can a Bluetooth dongle run DOOM? Join us to find out!

 

Take a look at the links below if you want to follow along, and as always, tell us what you think about this episode in the comments!

Direct download (52 MB)

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Privacy Report: What Android Does In The Background

November 18, 2021 by 76 Comments

We’ve come a long way from the Internet of the 90s and early 00s. Not just in terms of technology, capabilities, and culture, but in the attitude most of us take when accessing the ‘net. In those early days most users had a militant drive to keep any personal or identifying information to themselves beyond the occasional (and often completely fictional) a/s/l, and before eBay and Amazon normalized online shopping it was unheard of to even type in a credit card number. On today’s internet we do all of these things with reckless abandon, and to make matters worse most of us carry around a device which not only holds all of our personal information but also reports everything about us, from our browsing habits to our locations, back to databases to be stored indefinitely.

It was always known that both popular mobile operating systems for these devices, iOS and Android, “phone home” or report data about us back to various servers. But just how much the operating systems themselves did was largely a matter of speculation, especially for Apple devices which are doing things that only Apple can really know for sure. While Apple keeps their mysteries to themselves and thus can’t be fully trusted, Android is much more open which paradoxically makes it easier for companies (and malicious users) to spy on users but also makes it easier for those users to secure their privacy on their own. Thanks to this recent privacy report on several different flavors of Android (PDF warning) we know a little bit more on specifically what the system apps are doing, what information they’re gathering and where they’re sending it, and exactly which versions of Android are best for those of us who take privacy seriously.

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Streetfighter 2 placed on table top display with separate arcade control box

Game Like It’s 2021 On A McDonald’s Touchscreen Table

September 8, 2021 by 6 Comments

Some of you around the world may have come across these Android-based gaming tables installed in your local fast-food outlet, and may even have been lucky enough to paw at one that was actually working at the time.

Originally based on an ancient mini PC, with a 1080p flat panel LCD and a touch overlay, they would have been mind-blowing for small children back in the day, but nowadays we expect somewhat more. YouTuber [BigRig Creates] got his hands on one, in a less than pleasant condition, but after a lot of soap and water, it was stripped down and the original controller junked in favour of a modern mini PC. To be clear, there isn’t much left beyond the casing and display from the original hardware, but we don’t care, as a lot of attention was paid to the software side of things to get it to triple-booting into Windows 10, Android x86 and Linux running emulation station, covering all those table-gaming urges you may have.

Internally, there is a fair amount of room for improvement on the wiring side of things, and [BigRig] is quick to admit that, but that’s what this learning game is all about. Now, many of you will choke on the very idea of playing games on a table system like this, after all, it’s pretty obvious this will be really hard on the back and neck. But, it does offer the easy option to switch from landscape to portrait orientation, simply by walking around the side, so it does have an upside. Also you’ve got a handy place to dump your beer and the takeaway when it arrives, so maybe not such a bad thing to have in your apartment? And, yes, it does run Doom.

We were particularly amused by the custom boot logo as well as the slick custom art in emulation station. It’s attention to detail like this that makes a build a great one and a conversation piece at parties. Now if only he could sort out that wiring job.

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