Cheating at 5V WS2812 Control to Use 3.3V Data

If you’re looking to control WS2812 (or Neopixel) LEDs using a microcontroller running at 3.3 volts, you might run into some issues. The datasheet tells us that a logic high input will be detected at a minimum voltage of 0.7 * Vcc. If you’re running the LED at 5V, this means 5 V * 0.7 = 3.5 V will be needed for the WS2812 to detect a ‘1’ on the data line. While you might get away with using 3.3 V, after all the specification in the data sheet is meant to be a worst case, it’s possible that you’ll run into reliability issues.

So usually we’d say “add a level shifter to convert 3.3V to 5V” and this post would be over. We even have a whole post on building level shifters which would work fine for this application. However [todbot] at CrashSpace came up with a nifty hack that requires fewer components yet ensures reliability.

bigbutton-front-backFor the Big Button project at CrashSpace, [todbot] used an ESP8266 running at 3.3 volts and WS2812 LEDs running at 5 V. To perform the level shift, a signal diode is placed in series with the power supply of the first LED. This drops the first LED to 4.3 V, which means a 4.3 V * 0.7 = 3.01 V signal can be used to control it. The logic out of this LED will be at 4.3 V, which is enough to power the rest of the LEDs running at 5 V.

This little hack means a single diode is all that’s needed to control 5 V LEDs with a 3.3 V microcontroller. The first LED might be a little less bright, since it’s operating at a lower voltage, but that’s a trade off [todbot] made to simplify this design. It’s a small part of a well-executed project so be sure to click-through and enjoy all the thought [todbot] put into a great build.

Animated EV Charge Cable Enlightens Us

[ch00f] was searching for an idea to build for his father this Christmas, and cast his gaze across those novelty phone charging cables that have “flowing” LEDs along their length. Not one to stick to the small scale, he set out to create a flowing LED effect for a Tesla EV charger.

ch00f-led-ev-chargerThe basic components behind the build are a current transformer, a NeoPixel LED strip, and an ATtiny44 to run the show. But the quality of the build is where [ch00f]’s project really shines. The writeup is top notch — [ch00f] goes to great lengths showing every detail of the build. The project log covers the challenges of finding appropriate wiring & enclosures for the high power AC build, how to interface the current-sense transformer to the microcontroller, and shares [ch00f]’s techniques for testing the fit of components to ensure the best chance of getting the build right the first time. If you’ve ever gotten a breadboarded prototype humming along sweetly, only to suffer as you try to cram all the pieces into a tiny plastic box, you’ll definitely pick something up here.

Perhaps you’d like to check out this teardown of a Tesla Model S battery. Video after the break.

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Another Desktop LED Xmas Tree!

We love it when someone takes inspiration from one of our posts and comes up with their own twist on it. [Matthew] liked one builds he saw on Hackaday so much, he built his own LED desktop Xmas tree!

[Matthew] was inspired by [designer2k2]’s DIY desktop Xmas tree that was posted in October. To get started, he found a set of concentric WS2812 rings over on Ali Express. The five rings total 93 LEDs, plus a single WS2812 for the top of the tree. He also got a laser cut tree model from Thingiverse and had it cut, combining the LED rings with the tree in the final product

The whole thing running on a Digispark USB Development Board from DigiStump, the same as the original project. There aren’t many details in the video, but [Matthew] has put links to where he got the rings and the tree, the laser cutting service, a link to the DigiStump website as well as a link to [designer2k2]’s original tree project. There’s no source code yet, but [Matthew] says a link to it is coming along with some more pictures.

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More Blinky = More Better – The WS2812FX Library

The WS2812 is an amazing piece of technology. 30 years ago, high brightness LEDs didn’t even exist yet. Now, you can score RGB LEDs that even take all the hard work out of controlling and addressing them! But as ever, we can do better.

Riffing on the ever popular Adafruit NeoPixel library, [Harm] created the WS2812FX library. The library has a whole laundry list of effects to run on your blinkenlights – from the exciting Hyper Sparkle to the calming Breathe inspired by Apple devices. The fantastic thing about this library is that it can greatly shorten development time of your garden-variety blinkables – hook up your WS2812s, pick your effect, and you’re done.

[Harm]’s gone and done the hard yards, porting this to a bevy of platforms – testing it on the Arduino Nano, Uno, Micro and ESP8266. As a proof of concept, they’ve also put together a great demonstration of the software – building some cute and stylish Christmas decorations from wood, aluminium, and hacked up Christmas light housings. Combining it with an ESP8266 & an app, the effects can be controlled from a smartphone over WiFi. The assembly video on YouTube shows the build process, using screws and nails to create an attractive frame using aluminium sheet.

This project is a great example of how libraries and modern hardware allow us to stand on the shoulders of giants. It’s quicker than ever to build amazingly capable projects with more LEDs than ever. Over the years we’ve seen plenty great WS2812 projects, like this sunrise alarm clock or this portable rave staff.
As always, blink hard, or go home. Video after the break.

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Really Big Digital Clock Finds Use for Really Big 3D Printer

What does it take to make a really big digital clock? If [Ivan Miranda]’s creation is any gauge, it takes a really big 3D printer, an armful of Neopixel strips, and a ton of hot melt glue.

It looks like [Ivan]’s plus-size clock is mainly an exercise for his recently completed large-bed custom 3D printer, in itself a project worth checking out. But it’s a pretty ambitious project, and one that has some possibilities for enhancements. Each of the four seven-segment displays was printed separately, with a black background, translucent white for the segments, and recesses for five RGB LEDs each. The four digits and colon spacer are mated together into one display, and an ESP8266 fetches the time from a NIST server and drives the segments. What’s really interesting about [Ivan]’s projects is that he constrains himself to finishing them each in a week. That explains the copious amount of hot glue he uses, and leaves room for improvements. We’d love to see this display built into a nice walnut case with a giant red diffusing lens. Even as it stands it certainly makes a statement.

We’ve featured other outsized seven-segment displays before, but few as big as this one.

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Web Matrix Control Proves Power of ESP8266

LED matrix projects are all over the place, but this one is interesting for its simplicity: it’s an LED matrix that is driven straight from an ESP8266 board. [Ray] put it together as a quick project for his students to teach the basics of LED programming.

It’s built using a WS2812 LED matrix board he designed himself and his own ESPToy ESP8266 dev board. But the gist of the hardware is simply an ESP8266 and some WS2812’s. Where this gets interesting is with the user interaction side of things. The ESP makes WiFi and web serving easy, and [Ray] has build a simple HTTP GET API into the firmware. This is a great combination for the web dashboard and JavaScript-based animation programs [Ray] is demonstrating in the video below.

Just get on the same network and load up the module’s WiFi address for a graphical representation of the 5×7 LED matrix. Pick a color, turn pixels on or off, or choose a predefined pattern and send it to the hardware. This is a powerful way to get use input and with this as a guide it’s fast to set up for pretty much an application you can think of. Just work your way through the documents he put together for the workshop (Zip file link), including all of the code and the slides he used to run the workshop.

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Just In Time For Christmas! A DIY Desktop LED Tree

Okay, we haven’t even hit Halloween yet, but if you’re planning some kind of holiday project, now’s a good time to start ordering your parts, especially if you’re designing your own PCB. While there’s no PCB involved, [designer2k2] built a desktop “hollow” Christmas tree using some WS2812 RGB LEDs controlled by a microcontroller and powered by USB.

The board running [designer2k2]’s project is a Digispark, a USB powered board by Digistump which contains an ATtiny85. The LEDs, four different sized NeoPixel rings, plus a single pixel for the top, are connected together using some solid wire which makes for a very cool look. The code that runs on the ATtiny is the part that really makes this tree. The code cycles through colors and some light chaser effects, as well as a mode that shows a green tree with some white lights. The whole project is topped off by a routine that spells “XMAS” as you look at the tree from the top down.

We’ve seen some other Christmas tree hacks over the years controlled by various things, but this one is a fairly simple, cool design. [Designer2k2] also released the code for the tree and I’m sure a lot of us could come up with some more light designs.

Check out the video after the break:

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