DIY Button Matrix Lights Up And Speaks I2C

May 17, 2019 by Donald Papp 2 Comments

[David Johnson-Davies] always wanted an illuminated button matrix for projects, but cost was never very friendly. That all changed when he discovered a cheap source of illuminated pushbuttons on Aliexpress, leading to this DIY 4×4 illuminated button matrix design which communicates over I²C. The button states can be read independently of setting the light pattern, and an optional interrupt signal gets pulled low whenever there is a change detected. Not bad for one PCB plus about $10-worth in components!

The device uses every single pin on an ATtiny88, and because each button gets its own pin the keypresses can be detected with pin-change interrupts. The state reporting of buttons over I²C is unambiguous, even when multiple buttons are pressed simultaneously. A simple protocol provides all the needed functionality, and all connections are brought to the board’s edge to allow for easily tiling multiple panels.

The GitHub repository contains the code and PCB files and [David] helpfully shared the board files to OSH Park and PCBWay for easy ordering. In addition, he provides two demos (Tacoyaki and Tacoyaki+) which are games related to the classic Lights Out to show off the matrix.

Jumbo LEDs Make For A Handy ATtiny Beacon

May 1, 2019 by Tom Nardi 3 Comments

Inspiration can come from anywhere. Sometimes it’s just a matter of seeing an interesting part that you want to fiddle around with badly enough that you end up developing a whole idea, and potentially product, around it. That’s how [Bobricius] found himself creating this very slick little warning beacon, and looking at the end result, we think he made the right decision.

The Kingbright DLC-6SRD “jumbo” LED is actually six individual emitters built into a plastic diffuser. Interfacing with the device is simple enough; each LED has its normal anode and cathode leg, all you need to do is power them up. What [Bobricius] has created is a simple PCB design that the DLC-6SRD can plug right into, complete with a 2032 coin cell holder on the opposite side.

Of course, just lighting up all six elements at the same time wouldn’t be very interesting. [Bobricius] is controlling them individually right off of the digital pins of an ATtiny10 with the help of some Charlieplexing. This makes all kinds of interesting patterns possible, and as demonstrated in the video after the break, the current iteration of the project uses some very simple code to “rotate” the LED as if it was the flasher on an emergency vehicle.

The addition of a few blinking LEDs can make a world of difference in terms of nighttime visibility, so a cheap stick-on module that adds such a distinctive light pattern could be a very important safety device. It could also be useful for UAVs, following the FAA’s new rules which would mandate anti-collision lights for night flying.

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Get Twelve Charlieplexed PWM Outputs From An ATtiny85

February 24, 2019 by Donald Papp 8 Comments

Most of us are aware that charlieplexing can drive a large number of LEDs from a relatively small number of I/O pins, but [David Johnson-Davies] demonstrates adding another dimension to that method to create individually controlled PWM outputs as well. His ATtiny85 has twelve LEDs, each with individually-set brightness levels, and uses only four of the five I/O pins on the device.

Each LED can be assigned a brightness between 0 (fully off) and 63 (fully on). The PWM is done by using one of the timers in the ATtiny85 to generate a periodic interrupt, and the ISR for the interrupt takes care of setting the necessary ratios of on and off times for each charlieplexed output. The result? Twelve flicker-free LEDs with individually addressable brightness levels, using an 8-pin microcontroller and just a few passive components on a tiny breadboard. There’s even one I/O pin left on the ATtiny85, for accepting commands or reading a sensor.

[David] really wrings a lot out of the ATtiny series of microcontrollers with his compact projects, like his Tiny Function Generator (which recently got an update.) He also demonstrated that while charlieplexing is usually used with LEDs, charlieplexing can be used with switches just as easily.

Ultra Tiny PC Plays Snake

February 23, 2019 by Al Williams 9 Comments

[Steve Martin] used to do a comedy act about “Let’s get small!” You have to wonder if [Paul Klinger] is a fan of that routine, as he recently completed a very small 3D printed PC that plays snake. Ok, it isn’t really a PC and it isn’t terribly practical, but it is really well executed and would make a great desk conversation piece. You can see the thing in all its diminutive glory in the video below.

The 3D printer turned out a tiny PC case, a monitor, and a joystick. The PC contains an ATtiny1614, an RGB LED, and some fiber optic to look like case lighting. The monitor is really a little OLED screen. A 5-way switch turns into the joystick.

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Be Ready To Roll With Universal Electronic Dice

February 14, 2019 by Tom Nardi 4 Comments

There are applications you can download for your smartphone that can “roll” an arbitrary number of dice with whatever number of sides you could possibly want. It’s faster and easier than throwing physical dice around, and you don’t have to worry about any of them rolling under the couch. No matter how you look at it, it’s really a task better performed by software than hardware. All that being said, there’s something undeniably appealing about the physical aspect of die rolling when playing a game.

Luckily, [Paul Klinger] thinks he has the solution to the problem. His design combines the flexibility of software number generation with the small form factor of a physical die. The end result is a tiny gadget that can emulate anything from a 2 to 64 sided die with just 6 LEDs while remaining as easy to operate as possible. No need to tap on your smartphone screen with Cheetos-stained hands when you’ve got to make an intelligence check, just squeeze the Universal Electronic Die and off you go. Granted you’ll need to do some binary math in your head, but if you’re the kind of person playing D&D with DIY electronic dice, we think you’ll probably be able to manage.

The 3D printed case that [Paul] came up with for his digital die is very clever, though it did take him awhile to nail it down. As shown in the video after the break, it took seven iterations before he got the various features such as the integrated button “flaps” right. There’s also a printed knob to go on the central potentiometer, to make it easier to select how many sides your virtual die will have.

In terms of the electronics, the design is actually quite simple. All that lives on the custom PCB is a ATtiny1614 microcontroller, the aforementioned LEDs, and a couple of passive components. A CR2032 coin cell powers the whole operation, and it should provide enough juice for plenty of games as it’s only turned on when the user is actively “rolling”.

We’ve seen a number of very impressive electronic dice projects over the years, and it doesn’t look like the trend is slowing down anytime soon. Of course, if you absolutely must hear those physical dice rolling, we can help you with that too.

A Tiny IDE For Your ATtiny

February 8, 2019 by Tom Nardi 23 Comments

When writing code for the ATtiny family of microcontrollers such as a the ATtiny85 or ATtiny10, people usually use one of two methods: they either add support for the chip in the Arduino IDE, or they crack open their text editor of choice and do everything manually. Plus of course there are the stragglers out there using Eclipse. But [Wayne Holder] thinks there’s a better way.

The project started out as a simple way for [Wayne] to program the ATtiny10 in C under Mac OS, but has since evolved into an open source, cross-platform integrated development environment (IDE) for programming a wide range of ATtiny chips in C, C++, or Assembly. Not only does it integrate the source code editor and programmer, but it even bundles in documentation for common variants of the chips including block diagrams and pinouts; making it a true one-stop-shop for ATtiny hacking.

His IDE runs under Java, including OpenJDK, and [Wayne] provides a stable pre-built executable for those who don’t want to clone the whole GitHub repository. He’s included the GNU/AVR toolchains, though notes that testing so far has been limited to Mac OS, and he’s interested in feedback from Windows and Linux users. Assembly is done either with GNU AVR-AS, or an assembler of his own design, though the latter is currently limited to the ATTiny10.

To actually get the code onto the chip, the IDE supports using the Arduino as a programmer as well as dedicated hardware like the BusPirate or the USBasp. If you go the Arduino route, [Wayne] has even come up with a little adapter board which he’s made available through OSH Park to help wrangle the diminutive chips.

The ATtiny10 might have something of a learning curve, but in exchange this family of tiny microcontrollers offers an incredible amount of capability. When you’re working with what’s essentially a programmable grain of rice, the only limit is your own creativity.

Modernizing A Soviet-era LED Matrix

February 5, 2019 by Tom Nardi 10 Comments

Used in everything from calculators to military hardware, the 3LS363A is an interesting piece of vintage hardware. With a resolution of 5 x 7 (plus a decimal point), the Soviet-made displays contain no electronics and are simply an array of 36 green LEDs. It’s not hard to drive one of them in a pinch, but [Dmitry Grinberg] thought this classic device deserved a bit better than the minimum.

He’s developed a small board that sits behind the 3LS363A and allows you to control it over I2C for a much more modern experience when working with these vintage displays. Powered by the ATtiny406, his adapter board makes it easy to chain the modules together and even handles niceties like flipping the displayed image to account for different mounting positions. While most of us probably won’t have the chance to play around with these relatively rare displays, there’s still plenty of useful information here if you’re thinking of creating your own I2C gadgets.

In his write-up, [Dmitry] explains his rationale behind the design and some of the quirks of working with the display. For example he explains how he gave each column of the display its own FET, but to save space on the board ended up running the single decimal point (technically its own column) directly off of a spare GPIO pin. Relying on the low duty cycle, he even left current limiting resistors off the design. The end result is a tiny board that keeps the same footprint of the 3LS363A itself.

[Dmitry] went all out with developing the firmware for his new “smart” 3LS363A displays, and has written up documentation for the different commands he has implemented. From re-configuring the I2C address to updating the firmware, he’s made sure no stone was left unturned for this project. We’re not ones to shy away from a quick and dirty code, but it’s always nice to see when somebody has really put some thought into the software side of a project.

We’ve seen our fair share of oddball Soviet displays here at Hackaday, utilizing everything from heavy duty incandescent bulbs to remarkably tiny “intelligent” LEDs. While it’s unlikely any of them will dethrone the nixie as king of the retro display devices, it’s always interesting to see unusual hardware being used in the wild.