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]

Continue reading “Graphing Calculator Dual Boots With Pi Zero” →

Hacking A 30-year-old Russian VFD

March 3, 2018 by Rich Hawkes 8 Comments

Reddit user [InThePartsBin] found some VFDs (Vacuum Fluorescent Displays) on an old PCB on eBay. The Russian boards date from 1987 and have a bunch of through-hole resistors, transistors and a some mystery ICs, plastic wraps around the legs and the top of the tube is held steady by a rubber grommet (the tip itself goes through a hole in a board mounted perpendicular to the main board.) Being the curious kind of person we like, and seeing the boards weren’t too expensive, he bought some in order to play around with to see if he could bring them back to life.

After getting the VFDs lighting up and figuring out the circuitry on the back, [InThePartsBin] decided that a clock was the best thing to build out of it. It was decided that a specialized VFD driver chip was the easiest way to make the thing work, so a MAX6934 was ordered. To give the clock some brains, an ATmega328 was recruited and to keep time, [InThePartsBin] had some DS3231 real-time clock modules left over from a previous project, so they were recruited as well. A daughterboard was designed to sit on the back of the vintage board and hold the ‘328 and the VFD driver chip.

Once [InThePartsBin] soldered on the components it was time to fire it up and send 1’s to the driver to turn on all the segments on all the tubes. Success! The only thing that [InThePartsBin] has left to do is write the code for the clock, but all the segments and tubes are controllable now, so the hardware part is done. There are other VFD clock projects on the site: Check out this one, or this one, and bask in the beautiful steel-blue glow.

Via Reddit.

New Part Day: ATMegas With Programmable Logic

March 2, 2018 by Brian Benchoff 60 Comments

Since Microchip acquired Atmel, the fields of battle have fallen silent. The Crusaders have returned home, or have been driven into the sea. The great microcontroller holy war is over.

As with any acquisition, there is bound to be some crossover between two product lines. Both Atmel’s AVR platform and Microchip’s PICs have their adherents, and now we’re beginning to see some crossover in the weird and wonderful circuitry and design that goes into your favorite microcontroller, whatever that might be. The newest part from Microchip is an ATMega with a feature usually found in PICs. This is a Core Independent Peripheral. What is it? Well, it’s kinda like a CPLD stuck in a chip, and it’s going to be in the new Arduino board.

The ATMega4809 is the latest in a long line of ATMegas, and has the features you would usually expect as the latest 8-bit AVR. It runs at 20MHz, has 48 K of Flash, 6 K of SRAM, and comes in a 48-pin QFN and TQFP packages. So far, everything is what you would expect. What’s the new hotness? It’s a Core Independent Peripheral in the form of Configurable Custom Logic (CCL) that offloads simple tasks to hardware instead of mucking around in software.

So, what can you do with Configurable Custom Logic? There’s an application note for that. The CCL is effectively a look-up table with three inputs. These inputs can be connected to I/O pins, driven from the analog comparator, timer, UART, SPI bus, or driven from internal events. The look-up table can be configured as a three-input logic gate, and the output of the gate heads out to the rest of the microcontroller die. Basically, it’s a tiny bit of programmable glue logic. In the application note, Microchip provided an example of debouncing a switch using the CCL. It’s a simple enough example, and it’ll work, but there are a whole host of opportunities and possibilities here.

Additionally, the ATMega4809, “has been selected to be the on-board microcontroller of a next-generation Arduino board” according to the press release I received. We’re looking forward to that new hardware, and of course a few libraries that make use of this tiny bit of custom programmable logic.

Review: NEJE DK-8-KZ Laser Engraver

March 1, 2018 by Tom Nardi 100 Comments

When I got my first 3D printer I was excited, but now that I’m contemplating adding a forth to my collection, I have to come to the terms with the fact that these machines have all the novelty of a screwdriver at this point. Which is fine; getting the cost down and availability up is the key to turning a niche piece of technology into a mainstream tool, and the more people with 3D printers at home or in their workshop the better, as far as I’m concerned. But still, there’s a certain thrill in exploring the cutting edge, and I’ve been looking for something new to get excited about as of late.

Lasers seem like an interesting next step in my quest towards complete in-house fabrication capability, so I started researching cheap setups to get my feet wet. In the course of looking up diode-powered laser cutters, I came across the NEJE DK-8-KZ. At only 1W, there’s no question this device isn’t going to be cutting a whole lot. In fact, it’s specifically sold as an engraver. But given the fact that you can get one of these little guys for around $70 USD shipped, it’s hard to complain.

Now I wasn’t 100% sure what I would do with a laser engraver, but I thought it would be a good way to test the waters before putting serious money (and time) into something more powerful. Plus, if I’m being totally honest, I wanted to start on something on the lower end of the power spectrum because I’m terrified of blinding myself.

So what kind of laser do you get for $70? Let’s find out… Continue reading “Review: NEJE DK-8-KZ Laser Engraver” →

Quantifying Latency In Cheap RC Transmitters

February 26, 2018 by Tom Nardi 58 Comments

For those just starting out in the world of RC, a low cost transmitter like the Flysky FS-i6S can be very compelling. But is buying a cheap transmitter setting yourself up for failure down the line? The general feel in the RC community has been that cheaper transmitters have higher latency or “lag” on their inputs, which is precisely the kind of thing you want to avoid when flying along at 40+ MPH. As such, the general wisdom has been that your transmitter is one area where you don’t want to cheap out.

Wanting to put that theory to the test, [Marek Baczynski] set out to compare the response time between the Flysky FS-i6S and the more established Taranis X9D. In the video after the break, he uses his Saleae logic analyzer to time how long it takes movement on the transmitter sticks to get interpreted as servo commands at the receiver.

[Marek] connects the logic analyzer directly to the gimbals of both transmitters, allowing him to see user input before any processing is done by the electronics. It’s particularly interesting to see how the smooth analog curves of the gimbals are converted to a “staircase” digital output.

The final results of the latency test end up being fairly surprising. To put it simply: the cheaper Flysky radio not only more accurately interprets the user’s input, but does it considerably faster than the Taranis. [Marek] says he was so surprised by these results that he re-ran the test three times to verify.

But even taking into account the apparently higher fidelity of the cheap radio, he cautions you shouldn’t swap out your gear just yet. Higher end transmitters have a number of other features which make them worth hanging on to, even if the newer generation of radios is slightly faster. The real takeaway from this video is that if you’re just getting into the RC game, these cheaper transmitters aren’t necessarily the kiss of death the community makes them out to be.

Experiments like this and the recent detailed analysis of common hobby motors show just how seriously people take the world of RC. It’s unlikely this single experiment will quell the debate about “cheap” RC transmitters, but perhaps it’s a start.

Continue reading “Quantifying Latency In Cheap RC Transmitters” →

Successful Experiments In Multicolor Circuit Boards

February 26, 2018 by Brian Benchoff 19 Comments

Printed circuit boards have never been cheaper or easier to make. We’re not that far removed from a time where, if you wanted a printed circuit board, your best and cheapest option would be to download some proprietary software from a board house, use their terrible tool, and send your board off to be manufactured. A few copies of a 5x5cm board would cost $200. Now, anyone can use free (as in beer, if not speech) software, whip up a board, and get a beautifully printed circuit board for five dollars. It has never been easier to make a printed circuit board, and with that comes a new medium of artistic expression. Now, we can make art on PCBs.

PCB as Art

For the last year or so, Hackaday has been doing a deep-dive into the state of artistic PCBs. By far our biggest triumph is the Tindie Blinky Badge, an artistic representation of a robot dog with blinking LED eyes. [Andrew Sowa] turned some idiot into PCB coinage, and that same idiot experimented with multicolor silkscreen at last year’s DEF CON.

Others have far surpassed anything we could ever come up with ourselves; [Trammel Hudson] created an amazing blinky board using the standard OSHPark colors, and [Blake Ramsdell] is crafting full panels of PCB art. The work of Boldport and [Saar Drimer] has been featured in Marie Claire. The world of art on printed circuit boards has never been more alive, there has never been more potential, and the artistic output of the community is, simply, amazing. We are witnessing the evolution of a new artistic medium.

Printed circuit boards are a limited medium. Unless you want to shell out big bucks for more colors of silkscreen, weird colors of soldermask, or even multiple colors of soldermask, you will be limited to the standard stackup found in every board house. One color, the fiberglass substrate, will be a pale yellow. The copper layer will be silver or gold, depending on the finish. The soldermask will be green, red, yellow, blue, black, white, and of course purple if you go through OSH Park. The silkscreen will be white (or black if you go with a white soldermask). What I’m getting at is that the palette of colors available for PCB art is limited… or at least it has been.

For a few months now, Hackaday has been experimenting with a new process for adding colors to printed circuit boards. This is a manufacturing process that translates well into mass production. This is a process that could, theoretically, add dozens of colors to any small PCB. It’s just an experiment right now, but we’re happy to report some limited success. It’s now easy — and cheap — to add small amounts of color to any printed circuit board.

Continue reading “Successful Experiments In Multicolor Circuit Boards” →

These Small PCBs Are Made For Model Rocketry

February 24, 2018 by Donald Papp 18 Comments

Model rocketry hobbyists are familiar with the need to roll their own solutions when putting high-tech features into rockets, and a desire to include a microcontroller in a rocket while still keeping things flexible and modular is what led [concretedog] to design a system using 22 mm diameter stackable PCBs designed to easily fit inside rocket bodies. The system uses a couple of 2 mm threaded rods for robust mounting and provides an ATTiny85 microcontroller, power control, and an optional small prototyping area. Making self-contained modular sleds that fit easily into rocket bodies (or any tube with a roughly one-inch inner diameter) is much easier as a result.

The original goal was to ease the prototyping of microcontroller-driven functions like delayed ignition or altimeter triggers in small Estes rockets, but [concretedog] felt there were probably other uses for the boards as well and made the design files available on GitHub. (Thanks!)

We have seen stackable PCBs for rocketry before with the amazingly polished M3 Avionics project, but [concretedog]’s design is much more accessible to some hobbyist-level tinkering; especially since the ATTiny85 can be programmed using the Arduino IDE and the boards themselves are just an order from OSH Park away.

[via Dangerous Prototypes Blog]