Using An Old Smartphone In Place Of A Raspberry Pi

April 27, 2023 by Bryan Cockfield 63 Comments

The Raspberry Pi was a fairly revolutionary computing device when it came on the scene around a decade ago. Enough processing power to run a full Linux desktop and plenty of GPIO meant almost certain success. In the past year, though, they’ve run into some issues with their chip supplier and it’s been difficult to find new Pis, which has led to some looking for alternatives to these handy devices. [David] was hoping to build a music streaming server and built it on an old smartphone instead of the ubiquitous single-board computer.

Most smartphones are single-board computers though, and at least the Android devices are fully capable of running Linux just like the Pi. The only problem tends to be getting around the carrier or manufacturer restrictions like a locked bootloader or lack of root access. For [David]’s first try getting this to work, he tried to install Navidrome on a Samsung phone but had difficulties with the lack of memory and had to build the software somewhere else and then load it on the phone. It did work, but the stock operating system kept killing the process for consuming too much memory.

Without root access, [David] decided to try LineageOS, a version of Android which, among other benefits, is typically much more configurable than the stock version of Android that is shipped with smartphones. This allowed him to disable or uninstall anything not needed for his music server to free up enough memory. After some issues with transcoding the actual music files he planned on streaming, his music server was successfully up and running on a phone that would have otherwise been relegated to the junk drawer. The specific steps he took to get this working can be found on his GitHub page as well.

[David] also mentioned looking at PostmarketOS for this job which is certainly a viable option for some, but the Linux distribution for phones is only supported on a few devices. Another viable alternative for a project like this if no Raspberry Pis are available might be any of a number of Pine64 devices that might also be sitting around gathering dust, like the versatile Linux-based Pinephone.

Glowscope Reduces Microscope Cost By Orders Of Magnitude

March 24, 2023 by Bryan Cockfield 15 Comments

As smartphones become more ubiquitous in society, they are being used in plenty of ways not imaginable even ten or fifteen years ago. Using its sensors to gather LIDAR information, its GPS to get directions, its microphone to instantly translate languages, or even use its WiFi and cellular radios to establish a wireless hotspot are all things which would have taken specialized hardware not more than two decades ago. The latest disruption may be in microscopy, as this build demonstrates a microscope that would otherwise be hundreds of thousands of dollars.

The microscope is a specialized device known as a fluorescence microscope, which uses a light source to excite fluorescent molecules in a sample which can illuminate structures that would otherwise be invisible under a regular microscope. For this build, the light is provided by readily-available LED lighting as well as optical filters typically used in stage lighting, as well as a garden-variety smartphone. With these techniques a microscope can be produced for around $50 USD that has 10 µm resolution.

While these fluorescence microscopes do have some limitations compared to units in the hundred-thousand-dollar range, perhaps unsurprisingly, they are fairly impressive for such a low-cost alternative. More details about these builds can also be found in their research paper published in Nature. Even without the need for fluorescence microscopy, a smartphone has been shown to be a fairly decent optical microscope, provided you have the right hardware to supplement the phone’s camera.

Rollercoasters Are Triggering The IPhone’s Crash Detection System

October 12, 2022 by Lewin Day 68 Comments

Apple has been busy adding new features to its smartphone and smartwatch offerings. Its new iPhone 14 and Apple Watch 8 now feature a safety system that contacts emergency services in the event the user is in a automobile accident.

As with so many new technologies though, the feature has fallen afoul of the law of unintended consequences. Reports are that the “crash detection system” is falsely triggering on rollercoasters and in other strange circumstances. Let’s take a look at how these systems work, and why this might be happening.

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A Raspberry Pi Phone For The Modern Era

October 10, 2022 by Bryan Cockfield 43 Comments

While it might seem like mobile phones are special devices, both in their ease of use and in their ubiquity in the modern culture, they are essentially nothing more than small form-factor computers with an extra radio and a few specific pieces of software to run. In theory, as long as you can find that software (and you pay for a service plan of some sort) you can get any computer to work as a phone. So naturally, the Raspberry Pi was turned into one.

[asherdundas], the phone’s creator, actually found a prior build based around the Raspberry Pi before starting this one. The problem was that it was built nearly a decade ago, and hadn’t been updated since. This build brings some modernization to the antiquated Pi phone, and starts with a 3D printed case. It also houses a touchscreen and a GSM antenna to connect to the cell network. With some other odds and ends, like a speaker and microphone, plus a battery and the software to tie it all together, a modern functional Raspberry Pi phone was created, with some extra details available on the project page.

The phone has the expected features — including calling, texting, and even a camera. A small WiFi USB dongle allows it to connect to the Internet too, allowing it to do all of the internet browsing a modern smartphone might want to do. The only thing that it might be pretty difficult to do is install Android apps, and although there are ways to get Android apps working in Linux, it’s not always strictly necessary to have this functionality.

Powering A Cellphone With Gasoline

September 1, 2022 by Lewin Day 24 Comments

Batteries are a really useful way to store energy, but their energy density in regards to both weight and volume is disappointing. In these regards, they really can’t compete with fossil fuels. Thus, [bryan.lowder] decided to see if he could charge a phone with fossil fuels as safely and inoffensively as possible.

Obviously, with many national grids relying on fossil fuels for a large part of their generation, most of us are already charging our phones with fossil fuels to some degree. However, the aim here was to do so more directly, without incurring transmission losses from the long runs through the power grid. Continue reading “Powering A Cellphone With Gasoline” →

Turning The Back Of Your Phone Into A Touchpad

July 21, 2022 by Lewin Day 28 Comments

Smartphones use big touchscreens on the front as a useful tactile interface. However, our hands naturally wrap around the back of the phone, too. This area is underutilized as an interface, but the designers of BackTrack found a way to change that.

Touches on the 2D rear matrix are translated into a pair of touches on the linear line of pads on the front screen. This can then be reconstructed into the touch location on the rear touchpad.

The idea is simple. The project video notes that conductive tape can be placed on a multitouch touchscreen, allowing touches to be read at a remote location. Taking this concept further, BackTrack works by creating a 2D matrix on the back of the phone, and connecting this matrix to a series of pads in a row on the front touchscreen. Then, touches on the back touchpad can be read by the existing touchscreen on the front screen. Continue reading “Turning The Back Of Your Phone Into A Touchpad” →

Porting DOOM But In The Opposite Direction

July 20, 2022 by Lewin Day 4 Comments

DOOM was first released for MS-DOS, and is one of the pillar titles of the broader first-person-shooter genre. It’s also become a bit of a meme for being ported to any and every weird platform under the sun. Now, a group of developers in Costa Rica have found a way to flip that joke around – by porting an old mobile DOOM game back to the PC.

The game in question is DOOM RPG, made for BREW and Java-compatible phones in 2005. A group named GEC.inc has taken that game and ported it to Windows, outlining their work on the Doomworld forums. As with many such projects, the port is freely available, but doesn’t include the raw game files themselves due to copyright. You’ll have to find the gamedata yourself, and combine it with the files the group published on the forum to get it to work on a modern PC.

For those that have missed the turn-based role playing game based in the DOOM universe (Doomiverse?), today is a good day. No longer must you pine for your ancient, crusty Java smartphone of yesteryear. Now you can play the game on a less awful platform, and listen to the unique and compelling MIDI-esque soundtrack.

Doom ports are hot right now, whether it’s to forgotten Apple OSes or Sega arcade hardware. Video after the break.

Continue reading “Porting DOOM But In The Opposite Direction” →