Send Wireless TXT between Two TI Calculators


TI calculators with wireless circuitry

One day while sitting in class in a Cornell University schoolroom, [Will] and [Michael] thought how cool it would be to send text messages to each other via their Texas Instruments calculators.  Connecting the two serial ports with a serial cable was out of the question. So they decided to develop a wireless link that would work for both TI-83 and TI-84 calculators.

The system is powered by a pair of ATmega644’s and two Radiotronix RF Modules that creates a wireless link between the two serial ports. The serial ports are 3 wire ports, which can be used for several things, including acting as a TV out port. [Will] and [Michael] reverse engineered the port’s protocol and did an excellent job at explaining it in full detail. Because they are dealing with the lowest level of the physical protocol, there is no need for them to deal with higher levels like checksums, header packets, ext.

Be sure to stick around after the break to see a video of the project in action. It’s quite slow for today’s standards. If you have any ideas on how to speed it up, be sure to let everyone know in the comments.

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2048: Embedded Edition

Embedded touch version of 2048 tile gameHow ’bout that 2048 game? Pretty addictive, huh? Almost as addictive as embedded systems are, at least if you’re [Andrew]. Armed (pun intended) with a Nucleo F4 and a Gameduino 2 shield, he decided to have a go at making an embedded version of the popular tile pusher web game.

If you’re unfamiliar with the Nucleo boards from STMicroelectronics, check out our post on the Nucleo family from a couple of months ago. The Gameduino 2 shield ships with a 4.3″ touchscreen driven by an FT800 GPU EVE. [Andrew] wrote his own driver for it and his blog post goes into great detail about its programming model and the SPI read, write, and command functions he wrote. Full code is available from [Andrew]’s repo.

He started by generating a blank screen based on clues found in the Gameduino 2 source. Pretty soon he had rendered a rectangle and then a full 2048 board. A minor difference between [Andrew]’s creation and the original is that his always creates new tiles as ‘2’ while the web game cranks out the occasional ‘4’.

We were unable to embed [Andrew]’s gameplay videos, but you’ll find two on his blog.


Throwback Handheld Built with Modern Hobby Hardware


Remember all of those fantastically horrible handheld LCD games that hit the toy stores back in the ’90s. You know, the ones that had custom LCD screens to make for some fake animation. Here’s an example of what those should have been. It’s an LCD-based handheld with some soul.

The entire thing is roughly the size of a television remote, with a 3D printed case making it very presentable. But looking at the wiring which hides inside proves this is one-of-a-kind. The Arduino Pro Mini is probably the biggest difference in technology from back in the day compared to now. It has plenty of space for all of the different settings and games shown off in the clip below. The user interface itself is definitely a throw-back though. The Nokia 3310 screen boasts a whopping 84×48 pixel monochrome area. There are four buttons serving as a d-pad, and two as action buttons. Perhaps the greatest feature (besides the printed case we already mentioned) is the ability to recharge the internal battery via USB.

[Zippy314] built this with his son. What’s more fun: learning to program the games, or mastering them and discovering the bugs you missed along the way?


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Update: Tetris Handheld Get PCB and Case


Check out this sweet-piece of homemade handheld gaming! [Jianan Li] has been hard at work on the project and published the updates in two parts, one that shows off the PCB he had fabbed for the project, and another which details the 3D printed case. This is, of course, is the culmination of the Tetris project we first saw as an incredbily packed, yet thouroughly tidy breadboarded circuit.

We really enjoy the 8-sided PCB design which hosts all the parts and gives you a place to hold and control the unit, all without seeming to waste much real estate. The case itself is quite impressive. The openings for the square-pixel LED matrices (the original design had round pixels) and the bar graphs all have nice bevel features around them. The control area has a pleasant swooping cutout, with blue buttons which stand out nicely against the red. Check out the slider switch by his left thumb. He printed matching covers for this slider, and the two that stick out the bottom. Also on the bottom are female pin headers so that you don’t need to disassemble the case to interface with the electronics.

All of this and more are shown off in the clip after the break.

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Improve Your HT Ham Radio by Adding a Counterpoise Antenna Wire


We found an interesting tip that might just improve the performance of those small affordable handheld ham radios called a “Handy Talky” or HT for short in ham vernacular. [RadioHamGuy] posted an interesting video on adding a counterpoise antenna wire to an HT. He claims it will noticeably improve both transmit and receive by making a quarter-wave monopole into a makeshift dipole antenna system.

Per his instructions you basically add a short wire to the antenna’s outer ground connection or to an equivalent case screw that’s electrically connected to the antenna’s ground side. Apparently this can be referred to as a Tiger Tail and does make it look like your HT has a tail. You would construct a counterpoise antenna wire 11.5 inch for VHF, 6.5 for UHF and about 19.5 inches for an OK performing dual band VHF/UHF radio.

Normally with a handheld radio the counterpoise (ground) is your own body as you are holding the HT. This is because the capacitance of your body makes a good counterpoise under normal conditions. It would be interesting to hear what others find for performance when adding a counterpoise antenna wire.

You can watch [RadioHamGuy’s] full construction tutorial video for multiple radio types after the break.

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A Simple LED Flashlight Composed of a Relay and a Magnet

In our tips line we sometimes receive hacks that are amazing just because of their ingenuity. This relay-powered flashlight is definitely one of them. It has been named RattleGen by its creator [Berto], who apparently often makes simple hacks used in his everyday life (have a look at his YouTube channel).

To understand this hack, you first need to know (in case you didn’t already) that a magnet moving near a conductor (here a coil) induces a voltage at its terminals. This is called electromagnetic induction. In the picture you see above, you may distinguish a disassembled relay with a magnet located on the lever’s end. As a ferromagnetic metal is already placed inside the coil, the lever is by default ‘stuck’ in this position. By continuously pressing the latter on its other end, important voltage spikes are created at the coils terminals. [Berto] therefore used a bridge rectifier to transform the AC into DC, and a 1000uF capacitor to smooth the power sent to his super bright LED. A video of the system in action is embedded after the break.

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NESPoise – a Nice Looking NES Clone

[Dave] tipped us about the latest project he just finished: a posable, desktop NES clone arcade machine. This idea came to be when its creator gathered a few bits and pieces he had lying around: an NES Retro Entertainment System (Retrobit RES, found for less than $25) and an arcade stick with its buttons. [Dave] then bought a 7″ car DVD screen (less than $40) and started a first standard arcade-looking design with OpenSCAD. As the first draft was relatively boring, he let it mature for a bit until he got another idea, shown in the picture above.

The final result is made of 3D printed PLA and varnished luaun plywood which gives the console a VCS style retro look. Many hours were required to 3D print the different parts using a Makerbot Replicator 2. [Dave] disassembled his Retrobit RES to layout its parts inside the case and  also replaced the original voltage regulator with a 7805 on a big heatsink. This may be one of the best ‘nintendo’ hacks we have received over the years, but there have been others that also take cartridges.