Squeezing Every Bit From An ATMega

December 26, 2020 by Bryan Cockfield 16 Comments

While the ATMega328 is “mega” for a microcontroller, it’s still a fairly limited platform. It has plenty of I/O and working memory for most tasks, but this Battleship game that [thorlancaster328] has put together really stretches the capabilities of this tiny chip. Normally a Battleship game wouldn’t be that complicated, but this one has audio, an LED display, and can also play a fine rendition of Nyan Cat to boot, which really puts the Atmel chip through its paces.

The audio is played through a 512-byte buffer and an interrupt triggers the microcontroller when to fill the buffer while it works on the other processes. The 12×12 LED display is also fed through a shift register triggered by the same interrupt as the audio, and since the build uses so many shift registers the microcontroller can actually output four separate displays (two players, each with a dispaly for shots and one for ships). It will also eventually support a player-vs-computer mode for the battleship game, and also has a mode where it plays Nyan cat just to demonstrate its own capabilities.

We’re pretty impressed with the amount of work this small microcontroller is doing, largely thanks to code optimization from its creator [thorlancaster328]. If there’s enough interest he also says he will provide the source code too. Until then, be sure to check out this other way of pushing a small microcontroller to its limits.

Thanks to [Thinkerer] for the tip!

Discrete LEDs Make A Micro Display

December 24, 2020 by Kerry Scharfglass 5 Comments

Few things excite a Hackaday staff member more than a glowing LED, so it should be no surprise that combining them together into a matrix really gets us going. Make that matrix tiny, addressable, and chainable and you know it’ll be a hit at the virtual water cooler. We’ve seen [tinyledmatrix]’s work before but he’s back with the COPXIE, a pair of tiny addressable displays on one PCBA.

The sample boards seen at top are a particularly eye catching combination of OSH Park After Dark PCB and mysterious purple SMT LEDs that really explain the entire premise. Each PCBA holds two groups of discrete LEDs each arranged into a 5×7 display. There’s enough density here for a full Latin character set and simple icons and graphics, so there should be enough flexibility for all the NTP-synced desk clocks and train timetables a temporally obsessed hacker could want.

Continue reading “Discrete LEDs Make A Micro Display” →

A Tiny LED Matrix Is Better With Friends

December 23, 2020 by Kerry Scharfglass 8 Comments

When we last heard from [lixielabs] he was building Nixie tube replacements out of etched acrylic and LEDs. Well he’s moved forward a few decades to bring us the Pixie, a chainable, addressable backpack for tiny LED matrix displays.

Each Pixie module is designed to host two gorgeous little Lite-On LTP-305G/HR 5×7 LED dot matrix displays, which we suspect have been impulse purchases in many a shopping cart. Along with the displays there is a small matrix controller and an ATTINY45 to expose a friendly electrical interface. Each module is designed to be mounted edge to edge and daisy chained out to 12 or more (with two displays each) for a flexible display any size you need. But to address the entire array only two control pins are required (data and clock).

[lixielabs] has done the legwork to make using those pins as easy as possible. He is careful to point out the importance of a good SDK and provides handy Arduino libraries for common microcontrollers and a reference implementation for the Raspberry Pi that should be easy to crib from to support new platforms. To go with that library support is superb documentation in the form of a datasheet (complete with dimensions and schematic!) and well stocked GitHub repo with examples and more.

To get a sense of their graphical capabilities, check out a video of 6 Pixie’s acting as a VU meter after the break. The Pixie looks like what you get when a hacker gets frustrated at reinventing LED dot matrix control for every project and decided to solve it once and for all. The design is clean, well documented, and extremely functional. We’re excited to see what comes next! Continue reading “A Tiny LED Matrix Is Better With Friends” →

Status Display Lets Them Know You Can’t Play

December 20, 2020 by Kristina Panos 17 Comments

All this ongoing forced togetherness is great, but sometimes you just need to be able to pretend you’re alone so you can get some work done. So, how do you keep family members out of your home office? Our own [Bob Baddeley]’s free/busy indicator is about as simple as it gets.

The best part is that the status can been seen on both sides of the door so you don’t forget to keep it updated. Or maybe it’s the super-low part count. There’s no BLE, LoRa, or Wi-Fi, just two sets of red and green LEDs, a three-way switch, and a power source. Well, and current-limiting resistors of course.

[Bob] already had all the components on hand, including the nifty enclosure, which is another great thing about this build. Like [Bob] says, you could house the control side of this circuit in just about anything you’ve got lying around.

Young children might abuse this one, but this status indicator that lets the family request your presence with the push of a button.

Edge-Mounted LEDs Make This Spherical POV Look Fantastic

December 18, 2020 by Dan Maloney 19 Comments

For as many of them as we’ve seen, we still love a good persistence of vision display project. There’s something fascinating about the combination of movement and light creating the illusion of solid surfaces, and there’s always fun to be had in electromechanical aspects of a POV build. This high-resolution spherical POV display pushes all those buttons, and more.

Called “Flicker” for obvious reasons by its creator [Dan Foisy], this POV display started with a pretty clear set of goals in terms of resolution and image quality, plus the need to support animated images, all in a spherical form factor. These goals dictated the final form of the display — a PCB disc spinning vertically. The shaft has the usual slip rings for power distribution and encoders for position feedback. The PCB, though, is where the interesting stuff is.

[Dan] chose to use an FPGA to slice and dice the images, which are fed from a Raspberry Pi’s HDMI port, to the LED drivers. And the LEDs themselves are pretty slick — he found parts with 1.6 mm lead spacing, making them a perfect fit for mounting on the rim of the PCB rather than on either side. A KiCAD script automated the process of laying out the 256 LEDs and their supporting components as evenly as possible, to avoid imbalance issues.

The video below shows Flicker in action — there are a few problem pixels, but on the whole, the display is pretty stunning. We’ve seen a few other spherical POV displays before, but none that look as good as this one does.

Continue reading “Edge-Mounted LEDs Make This Spherical POV Look Fantastic” →

Little Red Night Light Is Just Right

December 13, 2020 by Kristina Panos 35 Comments

Don’t you hate getting up in the middle of the night to use the bathroom? The worst part is not being able to see what you’re doing, but if you turn on a light, you’ll lose your night vision. Nightlights are supposed to be the best solution, but are usually too bright for 3 AM excursions and can end up leaking light into the bedroom. What the bathroom needs is a purpose-built nightlight that uses red light so you don’t lose your night vision.

This simple, wall-mounted night light is just the thing. All it takes is two AA batteries, a resistor, a red LED, and an SPST push button. [Vchaney] even made their own battery contacts. The genius part of this build is in the adjustable LED, which is fitted into a ball that moves around in a socket so you can aim it wherever you need to see. All the files are available if you want to print one for yourself.

Those who sit might prefer to shine the light on the toilet paper roll. Here’s a smart roll holder that doubles as a night light, albeit a terribly bright one.

More LEDs Means Faster Print Times For 3D Printer, But There’s A Catch

November 18, 2020 by Donald Papp 13 Comments

[Jan Mrázek] is no stranger at all to home-grown improvements with his Elegoo Mars SLA 3D printer, and there is a lot going on in his experimental multi-LED upgrade which even involved casting his own lens array. In the end it did speed up his prints by a factor of three to four, though he cooked an LCD to failure in the process. Still, it was a fun project done during a COVID-19 lockdown; as usual there is a lot to learn from [Jan]’s experiences but the mod is not something he necessarily recommends people do for themselves.

[Jan] started by wondering whether better print quality and performance could be obtained by improving the printer’s UV light source. The stock printer uses a single large UV LED nestled into a reflector, but [Jan] decided to try making a more precise source of UV, aiming to make the UV rays as parallel as possible.

To do this, he took a two-pronged approach. One was to replace the single large UV LED with a 4×7 array of emitters plus heat sink and fans. The other was to make a matching array of custom lenses to get the UV rays as parallel as possible.

Casting one’s own lens array out of clear epoxy was a lot of work and had mixed results, but again, it was a lockdown project and the usual “is-this-really-worth-it” rules were relaxed. In short, casting a single custom lens out of clear epoxy worked shockingly well, but when [Jan] scaled it up to casting a whole 4×7 array of them, results were mixed. Mold deformation and artifacts caused by the areas between individual lenses robbed the end result of much of its promise.

More success was had with the array of UV emitters, which enabled faster curing thanks to higher power, but the heat needs to be managed. The stock emitter of the printer is about 30 W, and [Jan] was running his new array at 240 W. This meant a blazing fast one second exposure time per layer, but the heat generated by the new lighting was higher than anticipated. After only ten hours the LCD failed, probably at least in part due to the heat. [Jan] halved the power of the array down to 120 W and added an extra fan, which appears to have done the trick. Exposure time is two to three seconds per layer, and it’s up to 150 hours of printing without problems.

Again, it’s not a process [Jan] necessarily recommends to others (and he definitely recommends buying lenses if at all possible instead of casting them) but as usual there is a lot to learn from his frank sharing of results, both good and bad. We’ve seen 3D-printed lenses as well as adding WiFi connectivity to one of these hobbyist printers, and it’s great to see the spirit of hacking alive and well when it comes to these devices.