Graphing Calculator Dual Boots With Pi Zero

March 4, 2018 by Tom Nardi 41 Comments

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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Hackaday Links: September 3, 2017

September 3, 2017 by Brian Benchoff 35 Comments

The TI-83, TI-84, and TI-86 have been the standard graphing calculators in classrooms for two decades. This is the subject of an xkcd. Now, hopefully, there’s a contender for the throne. Numworks is a graphing calculator that looks like it was designed in at least 2006 (so very modern), and apparently, there’s a huge community behind it.

Juicero is shutting down. No one could have seen this one coming. The Juicero was a $700 press that turned proprietary, DRM’ed juice packs into juice and garbage. It was exquisitely engineered, but it turns out very few people want to spend thousands of dollars per year on DRM’ed juice. Oh, since the Juicero phones home, those $700 presses probably won’t work in the future.

Are you in the Bay area? Do you need test equipment? There’s a gigantic auction happening somewhere around San Jose. [Dave] tipped everyone off to this one, and this auction is pretty freakin’ spectacular. Spectrum analyzers, signal gens, a ‘mega zoom’ oscilloscope, and 4-channel, 500 MHz scopes for $50. There are a thousand lots in this auction. It’s nuts.

Everybody loves PCB art, and [Uri] has a guide for designing custom, functional electronic circuit boards. The toolchain used in this guide is Inkscape and KiCad, with blinky hearts, blinky pandas, and other blinky PCBs.

This one is a little out there even for us. Here’s how you build your own AA batteries. It’s a dozen #10 copper washers, a dozen or so #10 zinc washers, some cardboard, vinegar, salt, and some heat shrink tubing. The assembly of this battery is exactly what you would expect, and yes, it does work. Here’s the thing, though: The very crude tests suggest these batteries have a capacity of about 800-1000 mAh, which is far more than we would expect. Who has a programmable load and wants to do a few experiments? Also, these batteries are ‘rechargeable’ by taking them apart, sanding the crud off each washer, and adding new electrolyte.

[Jan] has made a name for himself stuffing synthesizers into tiny little microcontrollers. The latest project is the Infinity37, a polyphonic synth with MIDI, envelopes, and a whole bunch of cool stuff. Check out the video.

[rctestflight] is building a solar powered aircraft. It’s has a beautiful wing studded with solar panels. The latest flight was four hours, long enough to make piloting a plane through some FatSharks extremely tedious. Future developments will probably include a MPPT charging solution, and probably an autopilot.

The Newest Graphing Calculator Game

January 25, 2016 by Bryan Cockfield 7 Comments

Certainly everyone remembers passing time in a boring high school class playing games on a graphing calculator. Whether it was a Mario-esque game, Tetris, or BlockDude, there are plenty of games out there for pretty much all of the graphing calculators that exist. [Christopher], [Tim], and their colleagues from Cemetech took their calculator game a little bit farther than we did, and built something that’ll almost surely disrupt whatever class you’re attempting to pay attention in: They built a graphing calculator whac-a-mole game.

This game isn’t the standard whac-a-mole game, though, and it isn’t played on the calculator’s screen. Instead of phyiscal “moles” the game uses LEDs and light sensors enclosed in a box to emulate the function of the moles. In order to whack a mole, the player only needs to interrupt the light beam which can be done with any physical object. The team made extensive use of the ArTICL library which allows graphing calculators to interface with microcontrollers like the MSP432 that they used, and drove the whole thing with a classic TI-84.

This project is a fun way to show what can be done with a graphing calculator and embedded electronics, and it was a big hit at this past year’s World Maker Faire. Calculators are versatile in other ways as well. We’ve seen them built with open hardware and free software, And we’ve even seen them get their own Wi-Fi.

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Animated GIFs On A Graphing Calculator

June 17, 2015 by Brian Benchoff 26 Comments

The TI-84 Plus graphing calculator has a Z80 processor, 128 kilobytes of RAM, and a 96×64 resolution grayscale LCD. You might think a machine so lean would be incapable of playing video. You would be right. Animated GIFs, on the other hand, it can handle and [searx] is here to tell you how.

Before assembling his movie, [searx] first needed to grab some video and convert it to something the TI-84 could display. For this, he shot a video and used Premiere Pro to reduce the resolution to 95 by 63 pixels. These frames were saved as BMPs, converted to monochrome, renamed to pic0 through pic9, and uploaded to the calculator’s RAM.

To display the animated GIF, [searx] wrote a small program to cycle through the images one at a time. This program, like the images themselves, were uploaded to the calculator over the USB connector. Playing these animated GIFs is as simple as calling the program, telling it how fast to display the images, and standing back and watching a short flip-book animation on a calculator.

A Calculator With Free Software And Open Hardware

December 9, 2014 by Bryan Cockfield 57 Comments

We’re fond of open source things here. Whether it’s 3D printers, circuit modeling software, or a global network of satellite base stations, the more open it is the more it improves the world around us. [Pierre Parent] and [Ael Gain] have certainly taken these values to heart with their open handheld graphing calculator.

While the duo isn’t giving away the calculators themselves, they are releasing all of the hardware designs so that anyone can build this calculator. It’s based on a imx233 processor because this chip (and most everything else about this calculator) is easy to source and easy to use. That, and there is a lot of documentation on it that is in the public domain. All of the designs, including the circuit board and CAD files for the case, are available to anyone who is curious, or wants to build their own.

The software on the calculator (and the software that was used to design the calculator) is all free software too. The calculator runs Linux (of course) and a free TI simulator environment in the hopes of easing the transition of anyone who grew up using TI’s graphing calculators. The project is still in a prototype phase, but it looks very promising. Even though the calculator can already run Pokemon, maybe one day it will even be able to run Super Smash Bros as well!

Super Smash Bros On A Calculator

November 17, 2014 by Bryan Cockfield 14 Comments

Move over, BlockDude! There’s a new calculator game in town. [Hayleia] and a few other programmers have been hard at work on a clone of Super Smash Bros for graphing calculators that is sure to keep you busy in your next calculus class.

The game, called Smash Bros Open, is based on the Nintendo fighting game and is written specifically for monochrome z80 calculators (the TI-83 and TI-84 being the most ubiquitous of these). The game runs in 6 MHz mode with a simple background, or it can run in 15 MHz mode with a more complicated background. The programmers intend for the game to be open source, so that anyone can add anything to the games that they want, with the hopes of making the game true to its namesake.

Anyone who is looking to download a copy of this should know that Smash Bros Open is currently a work-in-progress. Right now both players need to play on the same calculator (with different keys), and Fox is the only playable character. The programmers hope to resolve the two player issue by using a second calculator as a game pad, or by linking the two calculators using Global CalcNet. As for the other characters, those can be added by others based on the existing code which is available on the project’s forum post!

Thanks to [Chris] for the tip.

THP Entry: A Theatrical Lighting Controller Powered By A Calculator

August 3, 2014 by Brian Benchoff 5 Comments

DMX

Theatrical lighting usually runs with the help of DMX, a protocol that’s basically MIDI for lights; small, lightweight, ancient, and able to run on the lowest spec computers imaginable. For his Hackaday Prize entry, [Alex] figured a regular ‘ol graphing calculator was sufficient to run a complete DMX controller, and with the help of an Arduino, figured out a way to do it.

The hardware for the system consists of a TI-84 graphing calculator, a few bits and bobs in the way of components, and an Arduino Pro Mini powered from the USB port on the calculator. The Arduino handles the transmitting of DMX packets at 250 kbaud using the DMXSimple library over a 5-pin XLR jack.

The software running on the calculator is where the novel part of the project begins. The software is designed to be extremely lightweight, sending packets to the Arduino using the 2-wire link cable. DMX Commands are wrapped up and transferred using the TI-83/84 link protocol, decoded on the Arduino, and sent out to the lighting rig.

While this probably won’t replace the multi-thousand dollar lighting consoles found in theatres, it’s still a very handy and portable tool for debugging lights. It’s also [Alex]’s My First Electronics Project™, and a pretty good one at that.

The project featured in this post is an entry in The Hackaday Prize. Build something awesome and win a trip to space or hundreds of other prizes.