When Are Dumb LEDs The Smart Choice?

A couple years ago I got into making electronic conferences badges by building a device for DEFCON 25 shaped like a dragonfly. Like all badges the most important design factor was quite literally how flashy it was, and two years ago I delivered on that with ten RGB LEDs. At the time I planned to hand-assemble each and every of the 105 badges at my kitchen table. Given those constraints, and a desire for electrical and programmatic simplicity, I landed on using APA102s (DotStar’s in Adafruit parlance) in the common 5050 sized package. They were easy to place, easy to design with electrically, simple to control, and friendly to a human pick-n-place machine. Though by the end of the production run I had discovered a few problems, the APA102s were a success.

This year I made a new and improved version of the dragonfly, but applying my lessons learned led me to choose a very different LED architecture than 2017. I swapped out the smart LEDs for dumb ones.

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ESP8266 Adds Slick Touchscreen Controls To A Stretch Limo

The popularity of the ESP8266 WiFi module has a lot to do with its ability to inexpensively connect to the Internet. However, [hwhardsoft]’s stretch limousine environmental control system explores another use for these modules: a simple way to tie together disparate systems with a common user interface.

On a basic level, the problem is one we’ve all faced: multiple devices with multiple control interfaces create an awkward user experience. Have you ever worked in an office with 6 brands of air conditioner requiring 6 different remotes? Because of its low-cost, support for Wi-Fi, serial, and GPIO, ESP8266 boards are a reasonable candidate to create a unified control system for multiple devices. This is even more true for the ESP32, as it adds Bluetooth support.

[hwhardsoft]’s use case is fairly straightforward. The limousine (a Lincoln stretch) has multiple LED lighting controllers, climate control, and a laser projector. This was not exactly a smooth user experience, so [hwhardsoft] tied all the controls to two slick touchscreen interfaces (presumably one for the driver and one for the passengers).

Each touchscreen sends commands over Wi-Fi using UDP to a control board that switches relays to control the different devices, as we’ve seen previously.

While relays are arguably not the ideal solution here, these control boards already existed and were functional, so it would have been wasteful to throw them out. An easy improvement suitable for future projects would be to use NPN transistors to simulate button presses on the remote controls. This works quite well and lowers cost, power, and parts count, while being faster, more reliable, and quiet.

If you wanted to build something similar in your home or office, but want to use an Android smartphone instead of a touchscreen, the Kivy Python module allows you to do just that. It’s quite easy to set up a simple interface with buttons, dropdown lists, and text inputs that send data to an ESP8266 over UDP.

Persistence Of Vision Death Star

Death Stars were destroyed twice in the Star Wars movies and yet one still lives on in this 168 LED persistence of vision globe made by an MEng group at the University of Leeds in the UK. While Death Stars are in high demand, they mounted it on an axis tilted 23.4° (the same as the Earth) so that they can show the Earth overlaid with weather information, the ISS position, or a world clock.

More details are available on their system overview page but briefly: rotating inside and mounted on the axis is a Raspberry Pi sending either video or still images through its HDMI port to a custom made FPGA-based HDMI decoder board.  That board then controls 14 LED driver boards mounted on a well-balanced aluminum ring. All that requires 75W which is passed through a four-phase commutator. Rotation speed is 300 RPM with a frame rate of 10 FPS and as you can see in the videos below, it works quite well.

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Fubarino Contest: A Sculpted Room With LEDs

[Sisam] and [Mclien] are a father and son team that built this sculptural room with an organic looking built-in seating area and sculpted lamp shades. When you have a room that looks this cool, the only option you have is to fill it with RGB LEDs, and it just so happens their light controller has a great Hackaday Easter egg.

The room lighting is provided by a Shifty VU shield, OctoBar LED controller, and a few of these RGB LED modules. All pretty standard for an RGB LED project, but where this contest submission really shines is the controller for all the room lights. It has three sliders for the red, green, and blue channels, beefy toggle switches for each light location, an LCD for showing the program mode, a rotary switch, and push buttons for cycling through stored setups.

The Easter egg for this project comes into play whenever the color value of the lights is set to Hackaday green, #00c100. When that happens, the Hackaday URL is displayed on the controller’s display.

Awesome work, and a really cool-looking room. We wouldn’t mind a tutorial on how you sculpted it, [Sisam].


This is an entry in the Fubarino Contest for a chance at one of the 20 Fubarino SD boards which Microchip has put up as prizes!