Simplifying Basic LED Effects

June 13, 2018 by Al Williams 24 Comments

There was a time when having a blinking blue LED on a project was all you needed to be one of the cool kids. But now you need something more complex. LEDs should not just snap on, they should fade in and out. And blinking? Today’s hotness is breathing LEDs. If that’s the kind of project you want, you should check out [jandelgado’s] jled library.

At first glance, an Arduino library for LED control might seem superfluous, but if you are interested in nice effects, the coding for them can be a bit onerous. If you don’t mind stopping everything while you fade an LED on (or off) then sure, you just write a loop and it is a few lines of code. But if you want to have it happen while other things continue to execute, it is a little different. The library makes it very simple and it is also nicely documented.

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Marvel At Soviet-era Smart Display’s Tiny Size

June 9, 2018 by Donald Papp 14 Comments

The Soviet-era 490IP1 LED. The digit is a mere 2.5 mm in height. Pictured with the Texas Instruments TIL306. [image: industrialalchemy.org]

It’s easy to assume that older components will be less integrated and bulkier than we might otherwise expect. Then something seems ahead of its time, like the teeny-tiny 490IP1 LED which was produced in the former Soviet Union. [AnubisTTP] obtained and shared images of this tiny integrated single digit LED display in which the number measures a scant 2.5 mm tall; in production it was made easier to read with an external bubble lens magnifier clipped to the outside. The red brick the 490IP1 is pictured with is the Texas Instruments TIL306, a relatively normal sized DIP component with similar functionality.

The 490IP1 is called an intelligent LED display because the package contains a decade counter and driver circuitry for the integrated seven-segment LED digit, complete with a carry signal that meant multiple displays could be chained together. It is notable not just due to its size, but because the glass cover makes it easy to see the die inside, as well as the wire-bonded pads.

It’s always fascinating to see glimpses of the development path that display technologies took. It’s easy to take a lot of it for granted today, but back before technology was where it is now, all sorts of things were tried. Examples we’ve seen in the past include the fantastic (and enormous) Eidophor projector which worked by drawing images onto a rotating disk of oil with an electron gun. On the smaller end of things, the Sphericular display used optics and image masks to wring a compact 0-9 numerical display out of only a few lamps at the back of a box.

Supercapacitors In A Servo: The “Forever” Flashlight

May 30, 2018 by Ben James 21 Comments

The principle is well understood: use a motor in reverse and you get a generator. Using this bit of knowledge back in 2001 is what kick-started [Ted Yapo]’s Hackaday Prize entry. At the time, [Ted] was searching for a small flashlight for astronomy, but didn’t like dealing with dead batteries. He quickly cobbled together a makeshift solution out of some supercapacitors and a servo-as-a-generator, hacked for continuous rotation.

A testament to the supercapacitors, 17 years later it’s still going strong – leading [Ted] to document the project and also improve it. The original circuit was as simple as a servo, protection diode, some supercapacitors, and a LED with accompanying resistor; but now greater things are afoot.

A DC-DC boost converter enables constant power through the LED, regardless of the capacitor voltage. This is achieved by connecting the feedback pin of an MCP1624 switcher to an INA199 current-shunt monitor. The MCP1624 kicks in at 0.65V and stays active down to 0.35V. This is all possible due to the supercapacitors, which happily keep increasing current as voltage drops – all the way to 0.35V. Batteries are less ideal in this situation, as their internal resistance increases as voltage drops, as well as increasing with age.

When testing the new design, [Ted] found that the gears on his servos kept stripping when he was using them to charge capacitors. Though at first he attributed it to the fact that the gears were plastic, he realized that his original prototype from 2001 had been plastic as well. Eventually, he discovered the cause: modern supercapacitors are too good! The ones he’d been using in 2001 were significantly less advanced and had a much higher ESR, limiting the charging current. The only solution is to use metal gear servos

Want to read more about boost converter design? We have the pros and cons of microcontrollers for boost converters, or this neat Nixie driver for USB power.

Tiny $25 Spectrometer Aims To Identify Materials With Ease

May 29, 2018 by Donald Papp 59 Comments

Reflectance spectrometers work on a simple principle: different things reflect different wavelengths in different amounts, and because similar materials do this similarly, the measurements can be used as a kind of fingerprint or signature. By measuring how much of which wavelengths get absorbed or reflected by a thing and comparing to other signatures, it’s possible to identify what that thing is made of. This process depends heavily on how accurately measurements can be made, so the sensors are an important part.

[Kris Winer] aims to make this happen with the Compact, $25 Spectrometer entry for The 2018 Hackaday Prize. The project takes advantage of smaller and smarter spectral sensors to fit the essential bits onto a PCB that’s less than an inch square. If the sensors do the job as expected then that’s a big part of the functionality of a reflectance spectrometer contained in a PCB less than an inch square and under $25; definitely a feat we’re happy to see.

Watch The Honeycomb Clock Gently Track Time

May 26, 2018 by Donald Papp 19 Comments

We love clocks here at Hackaday, and so does [John Whittington]. Last year he created this hexagonal honey clock (or “Honock”) by combining some RGB LEDs with a laser-cut frame to create a smooth time display that uses color and placement to display time with a simple and attractive system.

The outer ring of twelve hexagons is essentially the hour hand, similar to analog clock faces: twelve is up, three is directly to the right, six is straight down, and nine is to the left. The inner ring represents ten minutes per hex. Each time the inner ring fills, the next hex (hour) on the outer ring lights up. The whole display is flooded with a minute-long rainbow at noon and midnight. Watch it in action in the video, embedded below.

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Snowboard And Skateboard So Lit You Can Wipe Out And Still Look Good

May 18, 2018 by Bob Baddeley 5 Comments

[Nate] has made snowboarding cool with his Bluetooth connected board. Using 202 WS2812 LEDs carefully wrapped around the edge of the board and sealed with a conformal coating, it’s bright and waterproof. It’s controlled with an Arduino Nano and a Bluetooth classic board, as well as a large swappable USB battery bank; he can get roughly four hours of life at full brightness on his toy.

Where it gets even cooler is with a six-axis gyro connected to the Nano, which tracks the board movement, and the lights respond accordingly, creating cool patterns based on his speed, angles, and other factors. The app used to control this intense ice-rider is a custom app written using MIT App Inventor, which has the ability to work with Bluetooth classic as well as BLE. This came in handy when he made the 100-LED skateboard, which is based on a Feather with BLE and a large LiPo battery. The challenging part with the skateboard was making the enclosure rugged enough (yet 3D printed) to withstand terrain that is a lot less fluffy than snow.

The connected skateboard is controlled by his phone and a Feather.

The case is very rugged to protect the electronics.

Inside the very thick enclosure is a LiPo, Adafruit Feather Bluefruit, and MPU6050 accelerometer + gyro

We’ve seen others use flashlights and a professional connected board, but it’s been a few years and we’re due for a refreshing (and nostalgic) look back on the winter.

PIC16Maze Upgrades Secret Maze Game

May 9, 2018 by Steven Dufresne 4 Comments

We really like it when a reader is inspired by something they see on Hackaday, build on it, and let us know so we can pass it on. In this case, [Vegipete] made a secret maze game using a minimal number of parts and some neat software trickery.

It’s built around an 8-pin PIC16F18313 microcontroller, uses a joystick for input, and nine WS2812 LEDs to display the player and the surrounding maze walls. His inspiration was [David Johnson-Davies’] minimalist secret maze game built around the 8-pin ATTiny85. In that one, [David] cleverly used charlieplexing to get four pins to control four LEDs and four pushbuttons. [Vegipete’s] use of the WS2812 LEDs allowed him to control the LEDs with just one pin, and also get color while using three pins for the joystick and its button. He may use another pin in the future for sound and vibration.

He goes into some detail on the WS2812 protocol, how communication is done with the LEDs using just one pin and different pulse-lengths to represent 0 and 1. We’ll leave you to see his post for more depth but basically, he introduces a module on the PIC called the Configurable Logic Cell (CLC) which makes this easy and frees up processor cycles for the user’s code to do other things.

His source code is available on request but he does detail a neat software trick he uses for rotating the view. It may be confusing for some but as you move through the maze, your viewpoint rotates so that up is always the direction you’re facing. Luckily, the walls surrounding the user can be represented using 8-bits, four for east, west, north, and south, and four more for the corners. The maze is stored as a bitmap and from it, 8-bit values are extracted for the current position, each bit representing a wall around the position. To rotate the walls to match the user’s current orientation, the bits are simply shifted as needed. Then they’re shifted out to set each LED. Check it out in the video below.