The Android Bluetooth Connection

August 27, 2025 by Al Williams 14 Comments

Suppose someone came to talk to you and said, “I need your help. I have a Raspberry Pi-based robot and I want to develop a custom Android app to control it.” If you are like me, you’ll think about having to get the Android developer tools updated, and you’ll wonder if you remember exactly how to sign a manifest. Not an appealing thought. Sure, you can buy things off the shelf that make it easier, but then it isn’t custom, and you have to accept how it works. But it turns out that for simple things, you can use an old Google Labs project that is, surprisingly, still active and works well: MIT’s App Inventor — which, unfortunately, should have the acronym AI, but I’ll just call it Inventor to avoid confusion.

What’s Inventor? It lives in your browser. You lay out a fake phone screen using drag and drop, much like you’d use QT Designer or Visual Basic. You can switch views and attach actions using a block language sort of like Scratch. You can debug in an emulator or on your live phone wirelessly. Then, when you are ready, you can drop an APK file ready for people to download. Do you prefer an iPhone? There’s some support for it, although that’s not as mature. In particular, it appears that you can’t easily share an iPhone app with others.

Is it perfect? No, there are some quirks. But it works well and, with a little patience, can make amazingly good apps. Are they as efficient as some handcrafted masterpiece? Probably not. Does it matter? Probably not. I think it gets a bad rep because of the colorful blocks. Surely it’s made for kids. Well, honestly, it is. But it does a fine job, and just like TinkerCad or Lego, it is simple enough for kids, but you can use it to do some pretty amazing things.

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Google Will Require Developer Verification Even For Sideloading

August 26, 2025 by Maya Posch 115 Comments

Do you like writing software for Android, perhaps even sideload the occasional APK onto your Android device? In that case some big changes are heading your way, with Google announcing that they will soon require developer verification for all applications installed on certified Android devices – meaning basically every mainstream device. Those of us who have distributed Android apps via the Google app store will have noticed this change already, with developer verification in the form of sending in a scan of your government ID now mandatory, along with providing your contact information.

What this latest change thus effectively seems to imply is that workarounds like sideloading or using alternative app stores, like F-Droid, will no longer suffice to escape these verification demands. According to the Google blog post, these changes will be trialed starting in October of 2025, with developer verification becoming ‘available’ to all developers in March of 2026, followed by Google-blessed Android devices in Brazil, Indonesia, Thailand and Singapore becoming the first to require this verification starting in September of 2026.

Google expects that this system will be rolled out globally starting in 2027, meaning that every Google-blessed Android device will maintain a whitelist of ‘verified developers’, not unlike the locked-down Apple mobile ecosystem. Although Google’s claim is that this is for ‘security’, it does not prevent the regular practice of scammers buying up existing – verified – developer accounts, nor does it harden Android against unscrupulous apps. More likely is that this will wipe out Android as an actual alternative to Apple’s mobile OS offerings, especially for the hobbyist and open source developer.

From Smartphone To A Home Server

August 16, 2025 by Tyler August 27 Comments

Some people like their homelabs to be as big and fancy as possible, with racks of new or surplus server hardware sucking down power. [Hardware Haven] evidently has the opposite idea, given he just made a video about making the cheapest, smallest server possible: an Android phone.

Sure, it’s not going to be streaming terabytes of data at multiple gigabytes per second, but that’s not everyone’s use case. Don’t forget, flagship phones had multiple cores and gigabytes of RAM a decade ago, so even an old and busted smartphone has more than enough power for something like Home Assistant, which is what gets installed in this video.

After considering loading termux and rooting his device for Docker-on-Android, he opted for postmarket OS, the premiere Linux for old smartphones. That’s not because the Linux environment you get with termux wouldn’t work; it’s just that he wanted something native. To that end, he bought a somewhat worse-for-wear Xiaomi Mi A1 from eBay to get hardware Alpine-based postmarket could use.

Software wise, it was just a matter of following instructions and reading manuals — Linux is Linux, after all. The firewall proved to be his main challenge, though trying to branch out from Home Assistant to run Minecraft Server did run into Java issues [Hardware Haven] had no interest in troubleshooting. Hardware wise, though, well — do you want to leave a phone plugged in permanently? Smokey the Bear suggests you not, especially if you live near a forest. Besides, you probably don’t want your server on WiFi, and at least this smartphone wouldn’t charge when using a networking dongle.

That meant phone surgery: the battery came out, and 5 V from an old USB charger was piped into the battery charge controller via a diode. The diode was used for its voltage drop, to bring the 5 V supply down to a believable battery voltage — a buck converter might have been better, but you use what you have, and the diode drop doesn’t dissipate much power. Power dissipation is still one watt at idle, six during a stress test.

Given how cheap the phone was, and how little power this thing sips, [Hardware Heaven] has an excellent answer to those who say homelabbing is a rich person’s hobby. This project also reminds us that while our phones might not be as hackable as we’d like, they’re still far from totally locked down. You can even run NixOS on (some of) them.

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ChatGPT Patched A BIOS Binary, And It Worked

June 7, 2025 by John Elliot V 107 Comments

[devicemodder] wrote in to let us know they managed to install Linux Mint on their FRP-locked Panasonic Toughpad FZ-A2.

Android devices such as the FZ-A2 can be locked with Factory Reset Protection (FRP). The FRP limits what you can do with a device, tying it to a user account. On the surface that’s a good thing for consumers as it disincentivizes stealing. Unfortunately, when combined with SecureBoot, it also means you can’t just install whatever software you want on your hardware. [devicemodder] managed to get Linux Mint running on their FZ-A2, which is a notable achievement by itself, but even more remarkable is how it was done.

So how did [devicemodder] get around this limitation? The first step was to dump the BIOS using a CH341A-based programmer. From there, the image was uploaded to ChatGPT along with a request to disable SecureBoot. The resulting file was flashed back onto the FZ-A2, and all available fingers were crossed.

And… it worked! ChatGPT modified the BIOS enough that the Linux Mint installer could be booted from a flash drive. There are a bunch of bugs and issues to work through but in principle we have just seen AI capable enough to successfully patch a binary dump of BIOS code, which, for the record, is kind of hard to do. We’re not sure what all of this might portend.

So is uploading binaries to ChatGPT with requests for mods vibe coding? Or should we invent a new term for this type of hack?

SPACEdeck Is Half Cyberdeck, Half Phone Case, All Style

June 5, 2025 by Tyler August 17 Comments

It’s been at least a few hours since Hackaday last featured a cyberdeck, so to avoid the specter of withdrawal, we present you with [Sp4m]’s SPACEdeck, a stylish phone-based cyberdeck!

The SPACEdeck takes a Samsung Galaxy S24 and puts it into a handsome clamshell case with a wireless keyboard, turning the phone into a tiny-screened laptop that urges you not to panic. Is The Hitchiker’s Guide to The Galaxy available on the Playstore? Well, the e-book of the novel surely is, and having access to Wikipedia comes close. The design is building off (or out from, as the case may be) a 3D-printed phone case for the S24 by Digital Proto.

Given that the Galaxy S24 has more horsepower than the ancient Macbook we’re writing this on, this setup is probably going to be more useful than you might think, especially when paired with Termux to give you the full power of Linux.

Like some modern laptops, the screen can rotate 180 degrees for when the keyboard isn’t needed. The case will also allow for Nintendo Switch2 joycon integration, but that’s a work in progress for now. The connection points will also be modular so other accessories can be used. All files will be released once [Sp4m] is happy with how the Joycons are holding on, hopefully with a license that will allow us to remix this for other phones.

Given the supercomputers in our pockets, it’s really a wonder we don’t see more android-based cyberdecks, but most seem to stick to SBCs. Lately it seems the slabtop form-factor has been equally popular for cyberdecks, but it’s hard to beat a clamshell for practicality.

2025 Pet Hacks Contest: Feline Facial Recognition Foils Food Filching

May 25, 2025 by Tyler August 6 Comments

Cats are no respecters of personal property, as [Joe Mattioni] learned when one of his cats, [Layla] needed a special prescription diet. Kitty didn’t care for it, and since the other cat, [Foxy]’s bowl was right there– well, you see where this is going. To keep [Layla] out of [Foxy]’s food and on the vet-approved diet, [Joe] built an automatic feeding system with feline facial recognition. As you do.

The hardware consists of a heavily modified feed bowl with a motorized lid that was originally operated by motion-detection, an old Android phone running a customized TensorFlow Lite model, and hardware to bridge them together. Bowl hardware has yet to be documented on [Joe]’s project page, aside from the hint that an Arduino (what else?) was involved, but the write up on feline facial recognition is fascinating.

See, when [Joe] started the project, there were no cat-identifying models available– but there were lots of human facial recognition models. Since humans and cats both have faces, [Joe] decided to use the MobileFaceNet model as a starting point, and just add extra training data in the form of 5000 furry feline faces. That ran into the hurdle that you can’t train a TFLite model, which MobileFaceNet is, so [Joe] reconstructed it as a Keras model using Google CoLab. Only then could the training occur, after which the modified model was translated back to TFLite for deployment on the Android phone as part of a bowl-controller app he wrote.

No one, [Joe] included, would say that this is the easiest, fastest, or possibly even most reliable solution– a cat smart enough not to show their face might sneak in after the authorized feline has their fill, taking advantage of a safety that won’t close a bowl on a kitty’s head, for example–but that’s what undeniably makes this a hack. It sounds like [Joe] had a great learning adventure putting this together, and the fact that it kept kitty on the proper diet is really just bonus.

Want to go on a learning adventure of your own? Click this finely-crafted link for all the details about this ongoing contest.

Upgrading RAM On A Honda Infotainment System

February 10, 2025 by Maya Posch 5 Comments

Car infotainment systems somehow have become a staple in today’s automobiles, yet when it comes down to it they have all the elegance of a locked-down Android tablet. In the case of the Honda infotainment system that [dosdude1] got from a friend’s 2016/2017-era Honda Accord, it pretty much is just that. Powered by a dual-core Cortex-A15 SoC, it features a blazin’ 1 GB of RAM, 2 GB of storage and runs Android 4.2.2. It’s also well-known for crashing a lot, which is speculated to be caused by Out-of-RAM events, which is what the RAM upgrade is supposed to test.

After tearing down the unit and extracting the main board with the (Renesas) SoC and RAM, the SoC was identified as being an automotive part dating back to 2012. The 1 GB of RAM was split across two Micron-branded packages, leaving one of the memory channels on the SoC unused and not broken out. This left removing the original RAM chips to check what options the existing pads provided, specifically potential support for twin-die chips, but also address line 15 (A15). Unfortunately only the A15 line turned out to be connected.

This left double capacity (1 GB) chips as the sole option, meaning a total of 2 GB of RAM. After installation the infotainment system booted up, but only showed 1 GB installed. Cue hunting down the right RAM config bootstrap resistor, updating the boot flags and updating the firmware to work around the LINEOWarp hibernation image that retained the 1 GB configuration. Ultimately the upgrade seems to work, but until the unit is reinstalled in the car and tested it’s hard to say whether it fixes the stability issues.

Thanks to [Dylan] for the tip.

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