Down The Rabbit Hole And Back Out Again: Serial Over Headphone Jack

October 21, 2016 by Elliot Williams 14 Comments

[ttsiodras] tells an epic tale of getting a custom Debian kernel installed on an Asus MemoPAD (ME103K) tablet. Skipping to the end of the saga, he discovers what looks like serial data coming out on the headphone jack when the system boots, but the signal was so distorted that he couldn’t simply interpret it. The solution turns out to be attaching a level-converter chip.

A level converter is a non-inverting amplifier, usually with a Schmitt trigger for immunity against noise. In this case, it acts like a “binarizer” — outputting a high voltage when the input rises above a threshold, and a low when it drops below. It’s the right part when you need to clean up a messy digital signal, and in this case works just fine because the capacitive distortion effects slow down both the leading and trailing edges of the signal, keeping the serial data’s timing intact.

That was the spoiler. If you want to read up on putting a custom Linux on an Android device, check out [ttsiodras]’s first post where he backs the machine up, and the second where he gets his custom kernel up and running. If you’re ever faced with an Android tablet that hasn’t been owned yet, or if you just have a DIY streak, this should help you get started.

Using the audio jack for serial is actually not uncommon, and discovering a serial terminal that listens at boot time is our favorite way to wedge a Linux OS into odd devices. So when you see a funny, distorted signal coming out at 115,200 baud, take a moment to clean its edges up and see what you’ve got.

Ask Hackaday: DIY Handwriting Recognition

October 12, 2016 by Elliot Williams 40 Comments

Computer handwriting recognition is very cool by itself, and it’s something that we’d like to incorporate into a project. So we went digging for hacker solutions, and along the way came up with an interesting bit of history and some great algorithms. We feel like we’ve got a good start on that front, but we’re stuck on the hardware tablet sensor itself. So in this Ask Hackaday, we’re going to make the case for why you could be using a tablet-like device for capturing user input or doing handwriting recognition, and then we’re going to ask if you know of any good DIY tablet designs to make it work.

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Fight That Tesla Envy With A Tablet Dash For Your Car

May 31, 2016 by Gerrit Coetzee 37 Comments

[Aykut Çelik] uses some strong words to describe how he feels about his VW Polo’s current radio set-up. Words like, “useless,” are bandied about. What is a modern man supposed to do with a car that doesn’t have built-in navigation or Bluetooth connectivity with phones? Listen to the radio? There are actual (mostly) self driving cars on the road now. No, [Aykut] moves forward, not backwards.

To fix this horrendous shortcoming in his car’s feature package, he set out to install a tablet in the dash. His blog write-up undersells the amount of work that went into the project, but the video after the break rectifies this misunderstanding. He begins by covering the back of a face-down Samsung tablet with a large sheet of plastic film. Next he lays a sheet of fiberglass over the tablet and paints it with epoxy until it has satisfactorily clung to the back of the casing. Afterwards comes quite a bit of work fitting an off-the-shelf panel display mount to the non-standard hardware. He eventually takes it to a local shop which does the final fitting on the contraption.

The electronics are a hodgepodge of needed parts: An amplifier, to replace the one that was attached to the useless husk of the prior radio set; a CAN shield for an Arduino, so that he could still use the steering wheel buttons; and a Bluetooth shield, so that the Arduino could talk to the tablet. Quite a bit of hacking happened, and the resulting software is on GitHub.

The final assembly went together well. While it’s no Tesla console. It does get over the air updates whenever he feels like writing them. [Aykut] moves forward with the times.

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Bricked Intel Tablet Lives Again

May 17, 2016 by Jenny List 51 Comments

We’ve probably all taken a look at the rash of cheap Intel-Atom-based tablet computers and wondered whether therein lies an inexpensive route to a portable PC. Such limited hardware laden down with a full-fat Windows installation fails to shine, but maybe if we could get a higher-performance OS on there it could be a useful piece of kit.

[donothingloop] has an Intel tablet, a TrekStore Wintron 7, bought for the princely sum of $60. Windows 10 didn’t excite him, so he decided to put Ubuntu on it, or more specifically to put Ubuntu on an SD card to try it on the Wintron before overwriting the Windows installation. His problem with that was a bug in the Baytrail Atom chipset which limits the speed of SD card access and made Ubuntu very slow, and in trying to fix the speed issue he managed to disable a setting in the BIOS which had the effect of bricking the machine. A show-stopper when the BIOS is in a tiny SPI Flash chip and can’t be wiped or restored.

What followed was an epic of desoldering the BIOS chip and reflashing it, though that description makes the process sound deceptively easy. The specification says it is a 1.8V device, so after attempts to flash it using an ESP8266 and then a home-made level-shifter failed, he was stumped. With nothing but a cheap tablet to lose, he tried the chip in a 3.3V programmer, and to his amazement despite the significant overvoltage, it survived. Resoldering the chip to the motherboard presented him with a working tablet that would live to fight another day.

We’d have said that this work might reside in the “Don’t try this at home” category, but since Hackaday readers are exactly the kind of people who do try this kind of thing at home it’s interesting and reassuring to see that it can be done, and to see how someone else did it. A tablet that can be bricked through a mere BIOS setting though is something a manufacturer should be ashamed of.

We like unbricking stories here at Hackaday, something about winning against the odds appeals to us. In the past we’ve covered Blu-ray drives crippled by dodgy DRM and routers rescued with a Raspberry Pi, but the crown has to be taken by the phone rescued with a resistor made using paperclips and pencil lead.

Broken Android Tablet Mini-MAME Cabinet

March 6, 2016 by Elliot Williams 14 Comments

Everyone’s got an unused or even quasi-broken tablet lying around these days. [sairuk] has three kids, and somehow ended up with three broken tablets in short order. We’re not saying that correlation implies causality…

The digitizers were shattered, and since they were relatively cheap tablets to begin with, [sairuk] started thinking what could be done with a tablet that doesn’t have touch sensing anymore. He tried making an e-book reader for his kids, but somehow the idea of a MAME “cablet” (get it?) won out in the end. We’re not surprised: simple woodworking, gaming, and electronic hacking. What’s not to love?

This writeup goes into a lot more detail, so check that out too. He and his sons built up cardboard prototypes first (we love cardboard!) and then transferred their plans over to wood for the final “rough cut”. A PS1 controller reads out the joystick and buttons, and a PS1 -> USB adapter plus a USB-OTG cable connects that to the tablet. They also removed the batteries and built in a permanent power supply. Everything is simple and cheap, but the results are still impressive. Although they claim their build isn’t finished to the utmost, it looks pretty darn good to us.

We’re all frackers, so it’s satisfying to see a “junk” tablet put to good use. We’re wondering what [sairuk] is going to do with his other two tablets — we’ve got a suggestion for what he should do if he had twenty kids.

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Fail Of The Week: Dave Jones And The Case Of The Terrible Tablet

November 26, 2015 by Adam Fabio 74 Comments

Nothing spices up a quiet afternoon like the righteous indignance of an upset engineer, especially if that engineer is none other than [Dave Jones], on his EEVblog YouTube Channel. This week [Dave] has good reason to be upset. A viewer sent him what looked to be a nondescript 2010 era tablet from a company called Esinomed. From the outside it looked like a standard issue medical device. Opening up the back panel tells a completely different story though. This thing is quite possibly the worst hack job [Dave] (and we) have ever seen. This is obviously some kind of sales demo or trade show model. Even with that in mind, this thing is a fail.

The tablet is based upon an off-the-shelf embedded PC motherboard and touchscreen controller. [Dave] took some offense at the hacked up USB connector on the touchscreen. We have to disagree with [Dave] a bit here, as the video seems to show that a standard mini-b connector wouldn’t have fit inside the tablet’s case. There’s no excuse for the USB cable shield draped over the bare touch controller board though. Things go downhill from there. The tablet’s power supply is best described as a bizarre mess. Rather than use a premade DC to DC converter, whoever built this spun their own switch mode power supply on a home etched board. The etching job looks good, but everything else, including the solder job, is beyond terrible. All the jumps and oddly placed components make it look like a random board from the junk bin was used to build this supply.

The story gets even worse with the batteries. The tablet has horribly hand soldered NiMH cells shoved here, there and everywhere. Most of the cells show split shrink wrap – a sure sign they have been overheated. It’s hard to tell from the video, but it appears as if a few cells have their top mounted vent holes covered with solder. That’s a great way to turn a simple rechargeable battery into a pipe bomb. Batteries can be safely hand soldered – Radio Controlled modelers did it for decades before LiPo cells took over.

We’ve all hacked projects together at the last minute; that’s one of the things we celebrate here on Hackaday. However, since this is a commercial medical device (with serial number 11 no less) we have to stamp this one as a fail.

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Childhood Tech Exposure Is Slowly Killing The Keyboard

July 20, 2015 by Mike Szczys 113 Comments

I see the disturbing trend of moving away from keyboards as input devices — and I’m talking about a real, physical keyboard. This isn’t a matter of one decision that kills the keyboard, but an aggregate that is slowly changing the landscape. If you blink, you’ll miss it. We will not find ourselves in a world without keyboards, but in one where most of the available keyboards suck.

Rise of the Virtual Keyboard Generation

Is swipe-style keying the future of coding?

Tablets are great for screwing around, but when you want to get real work done in a reasonable amount of time, you grab a physical keyboard. In this scenario I don’t see the problem being those in the workforce going away from keyboards; it’s how the younger generations are learning to interact with technology that is troubling. The touchscreen is baby’s first computer. Families gather and the kids are handed their parent’s tablets while the grown-ups watch the game. More and more schools are outfitting classrooms with tablets, and for this I’m an advocate. Getting kids involved early in technology is imperative; knowledge evolves much more rapidly than printed textbooks. The tablet is a powerful tool in both of these areas. But most of the screen time kids get is with touchscreens and no physical keyboard.

How much time are K-12 kids spending in front of a physical keyboard? In the United States, if keyboard (typing) classes exist at all in a public school’s curriculum they’re usually only one-semester. Students who spend half of Elementary school using a tablet, and just one semester at a keyboard, are bound to prefer touchscreen-based entry over a physical keyboard.

Keyboard Erosion

We’ve already seen a strong push into touch-screens on laptops as the tablet market has grown. This is not necessarily a bad thing. Think of the computer mouse, it didn’t replace the keyboard, but augmented it and now is seen as a tool that itself is a necessity.

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