DIY Infrared Calculator Printer

December 28, 2021 by Chris Lott 5 Comments

[Ziggurat29] had been playing around with infrared protocols, and realized he had a spare point-of-sale printer kicking around in his junk box. So he decided to whip up his own calculator infrared printer by bolting on an STM32 Blue Pill module and an IR receiver. [Ziggurat29] initially thought such a homemade printer would be cheaper than a commercial HP 82240 IR printer, even a used one. In hindsight, these point-of-sale printers can be pricey. If you don’t have one laying around, it may be cheaper to buy one, but not as fun as building it yourself.

It used to be commonplace for calculators to have a printing mechanism — even entirely mechanical adding machines often had them. As electronic calculators became the norm, the printer began to fade away. Back in 1987, HP introduced a portable calculator printer, the HP 82240A (see HP Journal Oct 1987). The calculator could print using a one-way infrared protocol which came to be known as Redeye. This made good sense, since not every one needs a printing calculator. As well, if you had one of these printers, it could be used with multiple calculators. Later in 1991, HP added a bi-directional infrared link called SIR beginning with the HP 48SX calculator (see HP Journal Jun 1991), allowing calculators to communicate with each other or with an IR-equipped PC. Finally HP and other companies teamed up in 1995 to create the IrDA standards you are probably more familiar with. But a bunch of Redeye and SIR devices are still floating around, and even some modern calculators like SwissMicros offerings can still output to these printers.

If you want to make your own IR printer, be sure to check out [ziggurat29]’s Hackaday.io project. Also [Martin Hepperle] has an excellent writeup on an Arduino-based project on his site. We also covered a reverse project way back in 2011, an adaptor that prints over IR from wired serial signals. Have you found a printing calculator, or a standalone printer like this, to be useful in your workflow? Let us know in the comments below.

An Open Source Detector For Identifying Plastics

December 13, 2021 by Tom Nardi 18 Comments

One of the challenges involved in recycling plastic is determining the specific type of plastic a given item is actually made of. To keep up with demand, large scale recycling centers rely on various automated systems to separate different types of plastic from a stream of incoming material. But in less technologically advanced parts of the world, workers can find themselves having to manually identify plastic objects; a time consuming and error-prone process.

To try and improve on the situation, [Jerry de Vos], [Armin Straller], and [Jure Vidmar] have been working on a handheld open hardware device that they refer to simply enough as the Plastic Scanner. The hope is that their pocket-sized unit could be used in the field to positively identify various types of plastic by measuring its reflectivity to infrared light. The device promises to be very easy to operate, as users simply need to bring the device close to a piece of plastic, push the button, and wait for the information to pop up on the OLED display.

Or at least, that’s the idea. While the team eventually hopes to release a kit to build your own handheld Plastic Scanner, it seems that the hardware isn’t quite ready for production. The most recent work appears to have been put in, not unexpectedly, the development board that lets the team refine their process. The development unit combines an array of IR LEDs with wavelengths ranging from 850 to 1650 nanometers, a InGaAs photodiode connected to an ADS1256 24-bit analog-to-digital converter (ADC), and an Arduino Uno. In comparison, the final hardware uses a Raspberry Pi Zero and a smaller “breakout board” that contains the sensor and IR LEDs.

Browsing through the software repository for the project, we can see the device uses Python, TensorFlow Lite, and a database of IR reflectivity values for known plastics to try and determine the closest match. Obviously the accuracy of such a system is going to be highly dependent on the quantity of known-good data, but at least for now, it appears the user is responsible for building up their own collection or IR values.

As interesting as this project is, we’re a bit skeptical about its purely optical approach to identifying plastics. Automated recycling centers do use infrared spectroscopy, but it’s only one tool of many that are employed. Without additional data points, such as the density or electrostatic properties of the plastic being tested, it seems like the Plastic Scanner would have a fairly high margin of error. Just taking into account the wide array of textures and colors the user is likely to encounter while using the device will be a considerable challenge.

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Play Doom Or GTA V With Your Own Custom Controller And Xbox Emulator

December 2, 2021 by Orlando Hoilett 11 Comments

[Arnov] is bringing his own custom-made controller to the party and it is sure to impress. The design appears to have been inspired by the Xbox controller layout. Two joysticks for fine control of game characters, 4 face buttons, and two shoulder buttons. He opted for all through-hole components to make the assembly easier. No messing with tiny surface mount components here. We really appreciate the detail given to the silkscreen and the homage paid to a staple of retro gaming.

We were pretty impressed with how smoothly the controller translated to the game. He mentioned that was a huge improvement over his previous design. His original design had buttons instead of joysticks, but switching to joysticks gave him much better in-game control. That could also have a lot to do with the Xbox controller emulator running the background, but still.

Given that gift-giving season is upon us, you could really impress the video game enthusiast in your life with this as a custom gift. You could even run Retro games like Doom if you hook it up to a RetroPie. That ought to get a few people’s attention.

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HPi95LX Puts Linux In Your Palm

November 29, 2021 by Chris Lott 30 Comments

A few decades ago, palmtop computers were mostly based on MS-DOS, and while many users tried to mimic the UNIX experience, the results were mixed. Fast forward to the present and business-card-sized Linux computers modules abound. Canadian tinkerer [Rune Kyndal] decided to make his own Linux palmtop by sacrificing an old HP-95LX and replacing the guts with a Raspberry Pi Zero and a color LCD screen. We’re impressed with the rich set of features he has crammed into the limited volume of the case:

Raspberry Pi Zero W
Color LCD, 4.3 inch, 800×480 w/Backlight
Capacitive touch screen (not connected yet)
Stereo speakers + microphone
Ethernet 10/100
USB 2.0, 2 each
RS-232, DE-9 connector
microSD card
HDMI
IR dataport
Webcam (TBD)
LiPo Battery w/Charger

One problem that any palmtop faces is how to make a usable keyboard, and HP had one of the better designs. The keys are the same famous style as used in HP calculators. And while no human with normal hands could touch-type on it, the keyboard’s layout and tactile feel was well-suited to “thumb typing”. [Rune] made a good decision by keeping the original keyboard.

While fully functional, this is more of a proof of concept than a polished project. [Rune] primarily used bits and pieces that he had laying around. [Rune] says if he did it again, he would replace all the hot-glued accessory parts with a custom PCB, which is probably good advice. If you want to make your own, check out the project comments for some suggestions.

GBA Remote Play Upgrade Lets You Play PlayStation On The Bus

November 22, 2021 by Lewin Day 4 Comments

The Nintendo Game Boy Advance was basically the handheld gaming situation of its era, by virtue of the fact that it had no serious competitors in the market. The system was largely known for 2D games due to hardware limitations.

However, [Rodrigo Alfonso] has recently upgraded his GBA Remote Play system that lets him play PlayStation games and others on his classic Game Boy Advance. We first featured this project back in July, which uses a Raspberry Pi 3 to emulate games and pipe video data to the handheld for display, receiving button presses in return.

Since then, [Rodrigo] has given the project some upgrades, in the form of a 3D-printed case that mounts a battery-powered Pi directly to the back of the console for portable play. Additionally, overclocking the GBA allows for faster transfer rates over the handheld’s Link Port, which means more pixels of video data can be clocked in. This allows for more playable frame rates when running at 240×160, the maximum resolution of the GBA screen.

The result is a Game Boy Advance which you can use to play Crash Bandicoot on the bus just to confuse the normies. Of course, one could simply build a Raspberry Pi handheld from scratch to play emulated games. However, this route takes advantage of the GBA form factor and is pretty amusing to boot. Video after the break.

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Cramming A DS Inside A Gameboy

November 16, 2021 by Matthew Carlson 4 Comments

Many holiday recipes and console hacks share a common theme: cramming a thing inside another thing. Whether it’s turducken or a Nintendo DS inside a Gameboy, the result is always unexpected. The chassis for this mod is a humble Gameboy color with a Gameboy SP screen tackled on the top to serve as the secondary display. Unfortunately, this mod lost touch screen functionality, limiting some of the games you can play.

[TheRetroFuture] received the custom handheld from [GameboyCustom], which was somewhat damaged in shipping. The original screw mounts had to be removed and the case glued back together to fit the DS motherboard. So for [TheRetroFuture] to get inside to start troubleshooting involved a razor blade and patience. Testing various points and swapping components got [TheRetroFuture] closer to the root problems. The fix ended up being a few wires that came loose during shipping. Finally, after reseating a display connection and some careful soldering, it booted and started playing games.

Overall, it’s pretty impressive to see Mario Kart DS running on both screens on the tiny handheld. But you might be asking, why? Why shove one handheld inside another handheld? Sometimes it’s to gain new functionality like this Raspberry Pi inside a PSP body. Sometimes, it’s just because we can. Video after the break.

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Raspberry Pi And ESP32-S2 Team Up For MutantC_V4

August 30, 2021 by Tom Nardi 12 Comments

Back in 2019 we first came across the mutantC, an open source 3D printable Raspberry Pi handheld created by [rahmanshaber] that took more than a little inspiration from Sony’s VAIO ultra-mobile PCs (UMPCs) from the early 2000s. It was an impressive first effort, but it clearly had a long way to go before it could really be a practical mobile device.

Well after two years of development and three iterative versions of this Linux powered QWERTY slider, [rahmanshaber] is ready to show off the new and improved mutantC_v4. Outwardly it looks quite similar to the original version, with the notable addition of a tiny thumbstick and a pair of programmable buttons on the right side that can be used for input in addition to the touch screen. But inside it’s a whole other story, with so many changes and improvements that we hardly even know where to start.

Inside the mutantC_v4, showing off the ESP32-S2

Probably the most notable improvement is the addition of an ESP32-S2, specifically a bare ESP-12K module, to the main PCB. Previous versions of the hardware used an Arduino Pro Micro to interface with all the hardware, but the added horsepower of the ESP32 should come in handy with the array of sensors, controls, and NeoPixels that [rahmanshaber] has tasked the chip with. There’s even a buzzer and a coin-style vibration motor in there to provide some feedback to the user. While the board has changed significantly, it still retains compatibility with the Pi Zero, 2, 3, and 4.

Another notable addition is the expansion connector on the bottom of the handheld that has pins for I2C, UART, and 3.3 V. In the video below, [rahmanshaber] mentions that this feature was previously implemented with a standard 2×6 female header block, but is now using a far slimmer female USB-C port. We do wonder if it’s not a bit confusing to have this faux-USB port right next to the real one that’s actually used to charge the system, but with such cramped quarters occasionally you’ve got to make some tough decisions like that.

It’s quite inspiring to see how [rahmanshaber] has honed his skills since releasing the first version of the mutantC. The 3D printed parts and PCBs have matured considerably over the last two years, showing how quickly a dedicated hobbyist can advance their abilities. The most recent version has been entered in the 2021 Hackaday Prize. But the show isn’t over yet, as we hear v5 of this impressive handheld may tackle the Raspberry Pi 4 Compute Module.

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