24 Hours Of Temperature Data At A Glance

October 25, 2019 by Tom Nardi 7 Comments

In an era where we can see the current temperature with just a glance at our smartphones, the classic “Time and Temp” gadget sitting on the desk doesn’t have quite the same appeal. The modern weather fanatic demands more data, which is where this gorgeous full-day temperature display from [Richard] comes in.

The display, built inside of a picture frame, shows the temperature recorded for every hour of the day. If the LED next to the corresponding hour is lit that means the value displayed is from the current day, otherwise it’s a holdover from the previous day’s recordings. This not only makes sure all 24 LED displays have something to show, but gives you an idea of where the temperature might be trending for the rest of the day. Naturally there’s also a display of the instantaneous temperature (indoor and outdoor), plus [Richard] even threw in the current wind speed for good measure.

In the video after the break, [Richard] briefly walks us through the construction of his “Thermo Logger”, which reveals among other things that the beautiful panel art is nothing more exotic than a printed piece of A4 paper. The video also features a 3D model of the inside of the device which appears to have been created through photogrammetry; perhaps one of the coolest pieces of project documentation we’ve ever seen. We’ll just throw this out there: if you want to ensure that your latest build makes the front page of Hackaday, pop off that back panel and make some decent quality 3D scans.

Given the final result, it should come as no surprise to find that this isn’t the first incredible weather display that [Richard] has built. We previously covered another weather monitoring creation of his that needed two seperate display devices to adequately display all the data it was collecting.

Continue reading “24 Hours Of Temperature Data At A Glance” →

Light Emitting Logic Gates Built From Scratch

October 24, 2019 by Sharon Lin 44 Comments

What’s the weirdest computer you can think of? This one’s weirder.

[Dr. Cockroach] figured out a way to create an inverting NOT gate from just one LED and two resistors (one being a photo-resistor). The Dr. has since built AND, NAND, OR, NOR, XOR and XNOR gates, as well as a buffer, incorporating light into every logic gate.

Traditional inverters – NOT gates – are already made with diodes (typically not light-emitting), resistors (typically not light-dependent), and bipolar transistors. The challenge was to reduce the number of transistors. The schematic from the very first test shows the slight modifications [Dr. Cockroach] made to incorporate light into the logic gate using a 910 Ohm, output LED, and an LED and LDR in parallel.

The output is initially 4.5V for logic 1 and 1.5V for logic 0. Adding two 1N914 diodes and an AND gate ahead of the inverter create a two-input NAND gate. With the two diodes reversed and a 910 Ohm resistor removed, a NOR gate is created.

The next step was to build a S-R latch using the NAND gates and inverters, which holds some basic memory. From there, with some size reductions, a Master-Slave J-K Flip Flop, similarly using NAND gates and inverters, can be built. The current state of the project is a working sequencer and counter. You can even see a smooth sine wave propagating through the LED chaser, which is typically built with ICs or transistors but in this case is built simply with LEDs, LDRs, resistors, and capacitors.

The upcoming plan is to use the gates to build a processor that only uses diodes, resistors, and capacitors. While it’s probably not going to be nearly as fast as any processors we have today, it should be interesting (and educational!) to be able to visually track the flow of data from one logic gate over to the next. Continue reading “Light Emitting Logic Gates Built From Scratch” →

Painting With Light: The Homemade Pixelstick

October 16, 2019 by Sharon Lin 2 Comments

Light painting has long graced the portfolios of long-exposure photographers, but high resolution isn’t usually possible when you’re light painting with human subjects.

This weekend project from [Timmo] uses an ESP8266-based microcontroller and an addressable WS2812-based LED strip to paint words or custom images in thin air. It’s actually based on the Pixelstick, a tool used by professional photographers for setting up animations and photorealism shots. The equipment needed for setting up the light painting sticks runs in the order of hundreds, not to mention the professional camera and lenses needed. Nevertheless, it’s a huge step up from waving around a flashlight with your friends.

The LED Lightpainter takes the Pixelstick a few notches lower for amateur photographers and hobbyists. It directly supports 24-bit BMP, with no conversion needed. Images are stored internally in Flash memory and are uploaded through a web interface. The settings for the number of LEDs, time for the image row, and STA/AP-mode for wireless connections are also set by the web interface. The project uses the Adafruit NeoPixel, ArduinoJson, and Bodmer’s TFT_HX8357 libraries for implementing the BMP drawing code, which also allows for an image preview prior to uploading the code to the microcontroller. Images are drawn from the bottom row to the top, so images have to be transformed before updating to the LED painter.

Some future improvements planned for the project include TFT/OLED support, rainbow or color gradient patterns in the LEDs, and accelerometer or gyroscope support for supporting animation.

There aren’t currently too many galleries of DIY LED-enabled light paintings, but we’d love to see some custom modded light painting approaches in the future.

This isn’t the first LED light stick we’ve seen, if you’re interested in such things.

Hacking Pixmob Bands And Finding A Toolchain

October 15, 2019 by Lewin Day 16 Comments

The Pixmob band is an LED wrist strap, of the type often used at big concerts or other public events. Many have tinkered with the device, but as of yet, nobody was running custom code. It wouldn’t be easy, but [JinGen Lim] got down to work.

The wristbands are given out to concertgoers to create synchronized light shows in the crowd.

A teardown of a 2016 device revealed it consisted of an RGB LED, an IR sensor, a small EEPROM and a coin cell, which were all common parts. Unfortunately, the ABOV MC81F4204 microcontroller was a little more obscure. It’s a part that’s quite hard to find, and uses a proprietary programmer and an ancient IDE.

Searches online proved fruitless, and a working programmer remained outside [JinGen]’s grasp. Undeterred, he decided to simply walk into the company’s Korean headquarters and ask for help. As the part was end-of-life, they were unable to supply a programming device, but happily provided documentation for the chip that wasn’t publicly available. With this in hand, it was possible for [JinGen] to build his own programmer instead.

Booting up a copy of the ABOV IDE, with his newly-built programmer in hand, it was relatively easy to get the chip running custom code. Going the extra mile, [JinGen] even hacked the Arduino IDE to be partially compatible with the platform! A silicon error in the MC81F4204 design bricks the chips after only a few flash rewrites, so its never going to be the most useful platform, but it works nonetheless.

The Pixmob hardware has continued to evolve, and it’s unlikely modern units still use the same chip. Despite this, it’s a great example of what can be achieved by a little sleuthing and asking the right people the right questions. Others have attempted to hack similar products before, found at Disneyland and Coldplay concerts. You won’t catch this author at either, but if you’ve hacked something similar, be sure to reach out on the tip line!

Hacking The IKEA TRÅDFRI LED Power Supply

October 8, 2019 by Donald Papp 22 Comments

Just because something is being actively documented and tampered with by enthusiastic hackers doesn’t mean the information is handily centralized. There can be a lot of value in gathering disparate resources in one place, and that’s exactly what [Trammell Hudson] has done with his resource page for hacking the IKEA TRÅDFRI LED power supply with wireless interface. Schematic teardown, custom firmware images, it’s all there in one convenient spot.

Back in 2017, the IKEA TRÅDFRI hacking scene was centered around the LED light bulbs but as the group of products expanded, the rest of the offerings have also gotten some attention.

Why bother tampering with these units? One reason is to add features, but another is to make them communicate over your own MQTT network. And MQTT is the reason you are only a Raspberry Pi and a trip to IKEA away from the beginnings of a smart home that is under no one’s control or influence but your own.

Building A Cyberpunk Multi-Touch Input Device

October 6, 2019 by Tom Nardi 5 Comments

This multi-touch touch panel built by [thiagesh D] might look like it came from the retro-futuristic worlds of Blade Runner or Alien, but thanks to a detailed build video and a fairly short list of required parts, it could be your next weekend project.

The build starts with a sheet of acrylic, which has a grid pattern etched into it using nothing more exotic than a knife and a ruler. Though if you do have access to some kind of CNC router, this would be a perfect time to break it out. Bare wires are then laid inside the grooves, secured with a healthy application of CA glue, and soldered together to make one large conductive array. This is attached to a capacitive sensor module so it’ll fire off whenever somebody puts a finger on the plastic.

With RGB LED strips added to the edges, you could actually stop here and have yourself a very cool looking illuminated touch sensitive panel. But ultimately, it would just be a glorified button. There’s plenty of interesting applications for such a gadget, but it’s not going to be terribly useful attached to your computer.

To turn this into a viable input device, [thiagesh D] is using a Raspberry Pi and its camera module to track the number and position of fingertips from the other side of the acrylic with Python and OpenCV. His code will even pick up on specific gestures, like a three finger drag which changes the colors of the LEDs accordingly in the video below. The camera’s field of view unfortunately means the box the panel gets mounted to has to be fairly deep, but if recessed into the surface of a desk, we think it could look incredible.

Custom multi-touch panels have been a favorite project of hackers for years now, and we’ve got examples going all the way back to the old black and white days. But larger and more modern incarnations like this one have the potential to change how we interface with technology on a daily basis.

Continue reading “Building A Cyberpunk Multi-Touch Input Device” →