Writing Android Apps In C, No Java Required

Older Android devices can be had for a song, and in many cases are still packing considerable computational power. With built in networking, a battery, and a big touch screen, they could easily take the place of a Raspberry Pi and external display in many applications. As it so happens, Google has made it very easy to develop your own Android software. There’s only one problem: you’ve got to do it in Java.

Looking to get away from all that bloat and overhead, [CNLohr] set out to see what it would take to get 100% C code running on an Android device. After collecting information and resources from the deepest and darkest corners of the Internet, he found out that the process actually wasn’t that bad. He’s crafted a makefile which can be used to get your own C program up and running in seconds.

We mean that literally. As demonstrated in the video after the break, [CNLohr] is able to compile, upload, and run a C Android program in less than two seconds with a single command. This rapid development cycle allows you to spend more time on actually getting work done, as you can iterate through versions of your code almost as quickly as if you were running them on your local machine.

[CNLohr] says you’ll still need to have Google’s Android Studio installed, so it’s not as if this is some clean room implementation. But once it’s installed, you can just call everything from his makefile and never have to interact with it directly. Even if you don’t have any problem with the official Android development tools, there’s certainly something to be said for being able to write a “Hello World” that doesn’t clock in at multiple-megabytes.

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Ask Hackaday: Why Aren’t We Hacking Cellphones?

When a project has outgrown using a small microcontroller, almost everyone reaches for a single-board computer — with the Raspberry Pi being the poster child. But doing so leaves you stuck with essentially a headless Linux server: a brain in a jar when what you want is a Swiss Army knife.

It would be a lot more fun if it had a screen attached, and of course the market is filled with options on that front. Then there’s the issue of designing a human interface: touch screens are all the rage these days, so why not buy a screen with a touch interface too? Audio in and out would be great, as would other random peripherals like accelerometers, WiFi, and maybe even a cellular radio when out of WiFi range. Maybe Bluetooth? Oh heck, let’s throw in a video camera and high-powered LED just for fun. Sounds like a Raspberry Pi killer!

And this development platform should be cheap, or better yet, free. Free like any one of the old cell phones that sit piled up in my “hack me” box in the closet, instead of getting put to work in projects. While I cobble together projects out of Pi Zeros and lame TFT LCD screens, the advanced functionality of these phones sits gathering dust. And I’m not alone.

Why is this? Why don’t we see a lot more projects based around the use of old cellphones? They’re abundant, cheap, feature-rich, and powerful. For me, there’s two giant hurdles to overcome: the hardware and the software. I’m going to run down what I see as the problems with using cell phones as hacker tools, but I’d love to be proven wrong. Hence the “Ask Hackaday”: why don’t we see more projects that re-use smartphones?

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