Broken HP-48 Calculator Reborn As Bluetooth Keyboard

August 16, 2019 by Sven Gregori 8 Comments

Considering their hardware specification, graphing calculators surely feel like an anachronism in 2019. There are plenty of apps and other software available for that nowadays, and despite all preaching by our teachers, we actually do carry calculators with us every day. On the other hand, never underestimate the power of muscle memory when using physical knobs and buttons instead of touch screen or mouse input. [epostkastl] combined the best of both worlds and turned his broken HP-48 into a Bluetooth LE keyboard to get the real feel with its emulated counterpart.

Initially implemented as USB device, [epostkastl] opted for a wireless version this time, and connected an nRF52 based Adafruit Feather board to the HP-48’s conveniently exposed button matrix pins. For the software emulation side, he uses the Emu48, an open source HP calculator emulator for Windows and Android. The great thing about Emu84 is that it supports fully customizable mappings of regular keyboard events to the emulated buttons, so you can easily map, say, the cosine button to the [C] key. The rest is straight forward: scanning the button matrix detects button presses, maps them to a key event, and sends it as a BLE HID event to the receiving side running Emu84.

As this turns [epostkastl]’s HP-48 essentially into a regular wireless keyboard in a compact package — albeit with a layout that outshines every QWERTY vs Dvorak debate. It can of course also find alternative use cases, for examples as media center remote control, or a shortcut keyboard. After all, we’ve seen the latter one built as stomp boxes and from finger training devices before, so why not a calculator?

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Millenium Falcon HID: Get Unity To Talk To Teensy

August 15, 2019 by Inderpreet Singh 11 Comments

Here’s one that proves a hardware project can go beyond blinking LEDs and dumping massive chunks of data onto a serial console. Those practices are fine for some, but [dimtass] has found a more elegant hack for a more civilized age. His 3D Millennium Falcon model gets orientation data from his IMU as an an HID device.

The hardware involved is an MPU6050 6-axis sensor that is interfaced with a Teensy 3.2 board. [dimtass] documents his approach to calibrating the IMU going a bit further by using a Python script to generate offsets. We’ve advocated using Jupyter notebooks in the past and this is a good example of Jupyter plotting the data and visualizing the effect of the offsets in a second pass.

When in action, the Teensy reads IMU data and sends it over a USB RAW HID interface. For the uninitiated, HID transfers are more reliable than USB CDC transfers (virtual serial port) because they use smaller data chunks per event/transaction and usually don’t require special drivers. On the computer side, [dimtass] has written a small application that gets the IMU values over the RAW HID and then provides it to the visualization application.

A 3D Millennium Falcon model is rendered in Unity, the popular open source game development engine. Even though Unity has an API, this particular approach is more OS specific using a shared-memory technique. The HID application writes to a file (/tmp/hid-shared-buffer) which is then read by Unity to make orientation changes to the rendered model.

[dimtass] provides lots of details on the tools used to bring his project to life and it can be a great starting point for more projects that need interfacing sensors with a visualization system. We have seen ways to turn a person’s head into a joystick and if you need a deeper dive into Unity, look no further.

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KVM Foot Switch In A Few Steps

August 12, 2019 by Kristina Panos 6 Comments

[Radishmouse], despite the handle, is not a mouse guy. Give him a keyboard and he will get around just fine in any OS or program. As it is, he’s got a handful of ThinkPads, each running a different OS. He wanted to be able to switch his nice mechanical keyboard between two laptops without the hassle of unplugging and replugging the thing. His solution: a DIY KVM foot switch.

He’s been learning about electronics and 3D design, and this problem was the perfect opportunity to dig in and get his hands dirty. After learning enough about the USB protocol and switches to figure out what had to happen, he made a prototype from a pâte tub. Though undeniably classy, this vessel would never survive the rigors of foot-stomping in feline territory. Fortunately, [radishmouse] has also been learning about 3D design. After some trial and error, he came up with a sturdy, curvy 3D-printed two-piece enclosure. We particularly like the blocks built into the bottom piece that shore up the USB ports.

There are lots of reasons to build input controls for those under-utilized appendages at the ends of your legs. You could control your ‘scope with a probe in each hand, or use a foot switch to relocate an inconvenient power button.

Via [r/functionalprint]

A Macro Keyboard In A Micro Package

August 9, 2019 by Erin Pinheiro 9 Comments

Remember back in the early-to-mid 2000s when pretty much every cheap USB keyboard you could find started including an abundance of media keys in its layout? Nowadays, especially if you have a customized or reduced-sized mechanical keyboard, those are nowhere to be seen. Whenever our modern selves need those extra keys, we have to turn to external peripherals, and [Gary’s] Knobo is one that looks like it could’ve come straight out of a fancy retail package.

The Knobo is a small macro keypad with 8 mechanical Cherry-style keys and a clickable rotary encoder knob as its main feature. Each key and knob gesture can be customized to any macro, and with five gestures possible with the knob, that gives you a total of thirteen inputs. On top of that, the build and presentation look so sleek and clean we’d swear this was a product straight off of Teenage Engineering’s money-printing machine.

The actions you can do with those inputs range from simple media controls with a volume knob all the way to shortcuts to make a Photoshop artist’s life easier. Right now you can only reprogram the Knobo’s Arduino-based firmware with an In-Circuit Serial Programmer to change what the inputs do, but [Gary] is currently working on configuration software so that users without any programming knowledge will be able to customize it too.

Knobs are just one of those things that everyone wants to use to control their computers, much like giant red buttons. Alternative input devices can range from accessibility-designed to just downright playful. Whatever the inspiration is for them, it’s always nice to see the creativity of these projects.

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Laser Trip Wire Hides What You’re (Not) Working On

August 9, 2019 by Tom Nardi 15 Comments

We assume your office policy allows for reading Hackaday during work hours. But what about cruising reddit, or playing Universal Paperclips? There’s a special kind of stress experienced when attempting to keep one eye on your display and the other on the doorway; all the while convinced the boss is about to waltz into the room and be utterly disappointed in you.

But fear not, for [dekuNukem] has found the solution with Daytripper. This wireless laser tripwire communicates back to your computer using NRF24 (2.4 Ghz on the ISM band) and can be used to invisibly cordon off a door or hallway and fire a scripted action on your computer if its beam has been broken. Nominally this is used to send the keyboard command that hides all open windows, but we’re sure the imaginative readers of Hackaday could come up with all sorts of alternate uses for this capability.

The Daytripper transmitter uses a laser time-of-flight sensor, in this case the very small VL53L0X by STMicroelectronics. It’s best situated so the laser will be bounced straight back at it. It has a range of about four feet, which is perfect for covering a door, though a wide hallway could give it some trouble. [dekuNukem] admits that the 5 Hz scan rate means a sufficiently fast moving adversary might slip past the sensor, but if they’re trying that hard to see what’s on your monitor, they probably deserve a peek.

On the receiver side, there’s a small board that plugs into your computer and mimics a USB keyboard. It has a selector switch on the side that allows the user to set what key sequence will be “typed” once the system has been tripped. It has built-in support for minimizing all windows or locking the computer, or you can set it to send ALT + Pause, which you can listen for and act on however you see fit.

If you want to build your own Daytripper, the firmware and hardware are both available on GitHub under an MIT license. For those who prefer instant gratification, [dekuNukem] is doing a small production run and offering them up on Tindie.

Cash Register Hotkey Board Is On The Money

August 8, 2019 by Kristina Panos 8 Comments

When presented with a pile of free electronics, sometimes you grab things for their ‘someday’ potential. Other times, you know exactly what you’re after. [Bryce] got a big old cash register for free from school because they’ve moved on to using Square or something. He scored two VFDs and a solenoid as a side effect, but he was really after that sturdy keypad and its paper-label keycaps, ripe for customization.

Two hours of reverse engineering later, he knew where the button presses were going well enough to reach for a knockoff Arduino Pro Micro and a couple of shift registers. [Bryce] wanted his hotkey-board to handle keyboard presses as well as media key input, so he went with the HID-Project library over the standard-issue Arduino version. Of course, the whole point of making your own hotkey-board is customization. For [Bryce], that means Word shortcuts and quick access to Greek letters for all those engineering reports he must write. Dig that Half-Life lambda!

What? You don’t have access to free electronics? You could make a hotkey-board out of arcade buttons. Those things can really take a beating.

The Not Quite USB-C Of Nintendo Switch Accessories

August 4, 2019 by Roger Cheng 10 Comments

Historically gaming consoles are sold at little-to-no profit in order to entice customers with a low up-front price. The real profits roll in afterwards from sales of games and accessories. Seeking a slice of the latter, aftermarket accessory makers jump in with reverse-engineered compatible products at varying levels of “compatible”.

When the Nintendo Switch was released with a standard USB-C port for accessories, we had hoped those days of hit-or-miss reverse engineering were over, but reality fell short. Redditor [VECTORDRIVER] summarized a few parts of this story where Nintendo deviated from spec, and accessory makers still got things wrong.

Officially, Nintendo declared the Switch USB-C compliant. But as we’ve recently covered, USB-C is a big and complicated beast. Determined to find the root of their issues, confused consumers banded together on the internet to gather anecdotal evidence and speculate. One theory is that Nintendo’s official dock deviated from official USB-C dimensions in pursuit of a specific tactile feel; namely reducing tolerance on proper USB-C pin alignment and compensating with an internal mechanism. With Nintendo playing fast and loose with the specs, it makes developing properly functioning aftermarket accessories all the more difficult.

But that’s not the only way a company can slip up with their aftermarket dock. A teardown revealed Nyko didn’t use a dedicated chip to manage USB power delivery, choosing instead to implement it in software running on ATmega8. We can speculate on why (parts cost? time to market?) but more importantly we can read the actual voltage on its output pins which are too high. Every use becomes a risky game of “will this Switch tolerate above-spec voltage today?” We expect that as USB-C becomes more common, it would soon be cheapest and easiest to use a dedicated chip, eliminating the work of an independent implementation and risk of doing it wrong.

These are fairly typical early teething problems for a new complex technology on their road to ubiquity. Early USB keyboard and mice didn’t always work, and certain combination of early PCI-Express cards and motherboards caused damage. Hopefully USB-C problems — and memories of them — will fade in time as well.

[via Ars Technica]

[Main image source: iFixit Nintendo Switch Teardown]