Graphing Calculator Dual Boots With Pi Zero

The nearly limitless array of consumer gadgets hackers have shoved the Raspberry Pi into should really come as no surprise. The Pi is cheap, well documented, and in the case of the Pi Zero, incredibly compact. It’s like the thing is begging to get grafted into toys, game systems, or anything else that could use a penguin-flavored infusion.

But this particular project takes it to the next level. Rather than just cramming the Pi and a cheap LCD into his Numworks graphing calculator, [Zardam] integrated it into the device so well that you’d swear it was a feature from the factory. By exploiting the fact that the calculator has some convenient solder pads connected to its SPI bus, he was able to create an application which switches the display between the Pi and the calculator at will. With just a press of a button, he’s able to switch between using the stock calculator software and having full access to the internal Pi Zero.

In a very detailed write-up on his site, [Zardam] explains the process of getting the Pi Zero to output video over SPI. The first part of the battle was re-configuring the GPIO pins and DMA controller. After that, there was the small issue of writing a Linux SPI framebuffer driver. Luckily he was able to find some work done previously by [Sprite_TM] which helped him get on the right track. His final driver is able to push 320×240 video at 50 FPS via GPIO, more than enough to kick back with some DOOM.

With video sorted out, he still needed a way to interface the calculator’s keyboard with the Pi. For this, he added a function in his calculator application that echoed the keys pressed to the calculator’s UART port. This is connected to the Pi, where a daemon is listening for key presses. The daemon then generates the appropriate keycodes for the kernel via uinput. [Zardam] acknowledges this part of the system could do with some refinement, but judging by the video after the break, it works well enough for a first version.

We’ve seen the Pi Zero get transplanted into everything from a 56K modem to the venerated Game Boy, and figured nothing would surprise us at this point. But we’ve got to say, this is one of the cleanest and most practical builds we’ve seen yet.

[Thanks to EdS for the tip]

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Behold the Giant Eye’s Orrery-Like Iris and Pupil Mechanism

This is an older project, but the electromechanical solution used to create this giant, staring eyeball is worth a peek. [Richard] and [Anton] needed a big, unblinking eyeball that could look in any direction and their solution even provides an adjustable pupil and iris size. Making the pupil dilate or contract on demand is a really nice feature, as well.

The huge fabric sphere is lit from the inside with a light bulb at the center, and the iris and pupil mechanism orbit the bulb like parts of an orrery. By keeping the bulb in the center and orbiting the blue gel (for the iris) and the opaque disk (for the pupil) around the bulb, the eye can appear to gaze in different directions. By adjusting the distance of the disks from the bulb, the size of the iris and pupil can be changed.

A camera system picks out objects (like people) and directs the eye to gaze at them. The system is clever, but the implementation is not perfect. As you can see in the short video embedded below, detection of a person walking by lags badly. Also, there are oscillations present in the motion of the iris and pupil. Still, as a mechanism it’s a beauty.

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Hackaday Links: March 4, 2018

Guess what’s happening next weekend? The SoCal Linux Expo. SCALE is in its 16th year, and is the second greatest convention happening this year at the Pasadena Convention Center. The first, of course, is AlienCon this summer, with a special guest appearance by the guy with the hair on Ancient Aliens. What’s cool at SCALE? Tons of stuff! Tindie and Hackaday will have a booth, you’ll be able to check out the new stuff from System 76, and this is where I first picked up my most cherished possession, a Microsoft (heart) Linux sticker. NEED A TICKET? Cool, use the code ‘HACK’ to get 50% off!

[Muth] over on has been working on a very, very, very cool high voltage display. It’s a ИГГ1-64x64M, or a Gazotron, or something. What is it? It’s a two-color (green and red) 64×64 pixel VFD bitmap display. You want the king of all vacuum-based displays? Here you go. Progress on driving this display is slow, but it’s happening, and it will result in the coolest clock ever created.

Need a pick and place machine? Don’t want to shell out thousands for a Neoden? Here’s an Indiegogo campaign for the Open Placer, a machine that works with OpenPNP software. It’s got vision and a 295x195mm working area.

A few months ago, news came from Havana that the US embassy was under attack. Staffers at the US embassy in Cuba were feeling sick and apparently suffered neurological damage. Explanations ranged from poisoning to some sort of non-lethal weapon. Now, there might be a banal explanation. Researchers at the University of Michigan think it could simply be two ultrasonic sensors placed just the right distance apart. Acoustic interference happens, and that inaudible 35kHz signal becomes a maddening audible signal.

Last week, we had a great talk with OSH Park about PCBs. These Hack Chats are getting out of control, but at least we have a transcript. The biggest takeaway? They’re out of jellybeans, but OSH Park is working on new stickers.

Open Hardware Summit is the greatest con for all things Open Hardware. This year, it’s going to be in Boston. The Summit will be held on September 27th, 2018 at MIT Stratton Student Center. If you’d like to get there a week and a half early, the MIT ham flea market is the third Sunday of the month.

A Tabletop Star Wars Themed Lego Racer Game

When it comes to the title of undisputed king of the toy construction kit world, the Danes have it. Lego are ubiquitous in the toybox, and parents worldwide know the joy of stepping barefoot on a stray brick. Aside from the themed sets for youngsters and collectors, we see a lot of Lego in projects that make it to these pages. Sometimes they are from hardware hackers who’ve chosen Lego because they had some to hand or because of its utility, but at other times they come from the Lego community rather than the wider one.

Take the Star Racer from [Alexis Dos Santos] as an example of the former. It’s a table top racing game made entirely from Lego, and with control courtesy of Lego Mindstorms. It’s a real rolling road game, with a track made from five continuous belts of grey Lego sections, with obstacles attached to them. The Podracer slides from side to side at the front under user control, and the object is to avoid them as they come towards you at varying speed.

It’s a beautiful piece of work, and as well as the linked Flickr photographs it can be seen in the YouTube video below the break. The sticker says it’s a highly addictive game, and we’d be inclined not to disagree.

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No, Cat, This Is Not The Litter Box user [peterquinn] has encountered a problem with his recently unruly cat peeing under the dining table. Recognizing that the household cat’s natural enemy is the spray bottle, he built an automatic cat sprayer to deter her antics.

The build is clear-cut: an Arduino Uno clone for a brain, an MG995 servo, PIR sensor, spray bottle, and assorted electronics components. [peterquinn] attached the servo to the spray bottle with a hose clamp — ensuring that the zero position is pointing at the trigger — and running a piece of cabling around the trigger that the servo will tug on. Adding a capacitor proved necessary after frying the first Uno clone, as the servo powering up would cause the Uno to reset.

The code is set up to trigger the servo — spraying the cat twice — once the PIR detects the cat for more than ten seconds. After toying with a few options, [peterquinn] is using a 9V, 2A power supply that works just fine. For now, he hopes the auto-sprayer should do the trick. If it somehow doesn’t work, [peterquinn] has mused that a drastic upgrade to the vacuum may be necessary.

K40 Laser Cutter, Meet Raspberry Pi

The inexpensive Chinese K40 laser cutter has become the staple of many a small workshop within our community, providing a not-very-large and not-very-powerful cutter for a not-very-high price. As shipped it’s a machine that’s not without its flaws, and there is a whole community of people who have contributed fixes and upgrades to make these cutters into something a lot more useful.

[Alex Eames] bought a K40, and since he’s the person behind the Raspberry Pi business, when he switched from the supplied Corel-based software to the popular open-source K40 Whisperer his obvious choice was to run it on a Raspberry Pi. Since K40 Whisperer is written in Python he reasoned that the Pi’s ARM platform would not prevent its use, so he set to work and documented the process and his workflow.

It’s a straightforward enough process, and his K40 now has a Pi into which he can SFTP his files rather than the inevitable old laptop that accompanies most K40s. With so many K40 improvements created by its community, we find it surprising that some enterprising Chinese manufacturer hasn’t seen the opportunity to make a quick buck or two extra and incorporate some of them into their products at the factory, including one of the many single board computers that could perform this task.

We’ve covered a lot of K40 stories over the years, if you are new to this machine you might like to take a look at this story of bringing one to life.

Coolant Hoses Retasked to Lend a Helping Hand

Everyone needs a helping hand in the shop once in a while, and most of us have gone the traditional route and bought one of those little doohickies with the cast iron base and adjustable arms terminated in alligator clips. They’re cheap, they’re readily available, and they’re “Meh,” at best.

In the quest for better hands, [Jeremy S. Cook] came up with this custom design for a benchtop aid, and we’re pretty impressed. There are commercial designs out there that use the same flexible coolant hoses, called Loc-Line, which are often seen spewing coolant on metalworking machines like mills and lathes. But the stuff is cheap, and with a little work, you can build something that fits your needs rather than working around a commercial design. [Jeremy] cut the base for his out of standard dimensional lumber with a CNC router, but the same thing could be done with simple hand tools. A 3D-printed base would be easy enough, too, although it might require some ballast to keep it from wiggling on the bench. The Loc-Line hoses were easily modded to hold alligator clips, and we can imagine other accessories too, like lights and a magnifier — or even a 3D-printed scoop to suction soldering fumes through the hose.

It’s a simple project, to be sure, but a useful one, and we like the design. But don’t think [Jeremy] isn’t thinking big, too — remember his magnificent lighted polycarbonate Strandbeest?

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