Tag Archives: Led(s)

LED strips installation beyond Xmas

via Arduino Blog


The installation of Dmitry Morozov (:: vtol: :)”Wave is my nature” exhibited at the Mars center in Moscow is focused on the concept of Wave as the basis of all audiovisual art:

The project draws from the theory of Wave–particle duality which considers the light to be a particle and a wave at the same time. In this case, the notion of the “wave” is uniform for the sound wave, light wave and a “tangible” kinetic wave with wide amplitude, physically presented in the space as stretched cables moved by a system of motors. The piece also refers to the topic of physical modeling of the wave processes which take place in various media and materials: “string”, “data flow”, “visualisation of sound”, “sonification of light” etc. In general, the installation can be viewed as a kinetic spacial light installation which reacts to the presence of audience and creates an autonomous sound and light composition.

The artist used led strips, servo motors, 2-channel sound system, ir motion sensors running on Arduino Mega and Arduino Uno:

Lab LED constant current controller board

via Dangerous Prototypes


Ladvien blogged about his Lab LED constant current controller board project he made using DirtyBoard PCBs:

A little lab controller PCB I’m working on. It centers around four high-power constant current circuits meant to be driven by an Atmega328’s PWM.
I hate working on anything mechanical in dim light; comes from dropping parts down under the engine when working on cars. I’m also pretty particular about my type of light. The “Cool White” or CFLs really bother me. I feel like I’m a bug headed towards a bug-zapper.

I have a few design goals,
1. Warm white is the way to go. I’m shooting for four 1k lumen warm-white LEDs at 12v at ~1A.
2. I’ve a plug for an Arduino Pro Mini (APM). It’s hard to fight the APM when it comes to small footprint and versatility, oh, and price. They are super cheap if you buy them on eBay.
3. I want to make a BLE serial interface using my HM-10. This would allow me to control my LEDs using my iOS devices.
4. The A4 and A5 pins are broken out, this is meant to make the boards chainable using I2C.

Check out the video after the break.

Replacement LED driver for AN6877

via Dangerous Prototypes


Dilshan Jayakody writes:

AN6877 is linear AF level meter IC produced by Panasonic and it is commonly found on many audio equipment. This chip is no longer manufactured by Panasonic and finding replacement chip for AN6877 is also quiet difficult.
The circuit described in this article is design to replace AN6877 base LED drivers and it is based on commonly available components. This replacement LED driver is design using 10, MMBT3904/2N3904 transistors and it can easily modify to get necessary number of outputs.

Project info at Jayakody’s blog and elect.wikispaces.com.

Light painting with a Raspberry Pi

via Raspberry Pi

Before we get to the meat of today’s post, we’ve two bits of news. Just over an hour ago we watched the Soyuz rocket carrying British ESA astronaut Tim Peake, who will be in charge of the two Astro Pis on the ISS, lift off. The Soyuz will dock with the ISS around 17:24 GMT today: please join us following Tim’s progress on Twitter from about 16:45 GMT. (You can also watch live footage at NASA TV.)

In other Raspberry Pi community news, we’re very pleased to announce that Yasmin Bey, a 14-year-old Pi developer from Southend, organiser of school computer clubs, and friend of many at Pi Towers, won the EU Digital Girl of the Year award, which this year was awarded jointly with Niamh Scanlon from Dublin. We’ve been watching Yasmin’s progress over the last year or so: she’s an astonishingly focussed and exceptionally smart girl, and we wish her all the success in the world. Well done Yasmin – we’re really proud of you!

Back to light painting.


LadyAda from New York’s Adafruit dropped me a very short email at the end of last week, saying “You must see this.” As usual, she was right. This is one of the most eye-catching projects we’ve come across this year.

What you’re seeing in the photo above is a persistence of vision (POV) effect, where a slow shutter speed is used to capture a row of LEDs which change as they’re moved across the frame (in this instance by someone carrying and sweeping the LEDs from one side of the picture to the other over a period of a couple of seconds).


It’s a really impressive effect, and it’s a rig you should be able to build yourself at home, using a Raspberry Pi and some additional kit. Adafruit has covered the subject before, but they’ve discovered that their new DotStar LEDs make things much easier and much better looking. DotStar LEDs use generic 2-wire SPI, so you can push data much faster than with the NeoPixels’ 800 KHz protocol, and you don’t need to mess around with specific timing functions. They also have much higher pulse width modulation (PWM), which means that things look a lot smoother and less flickery than in POV projects made with other LEDs. Result: cleaner, more detailed light painting.


Adafruit have a made a very thorough tutorial which will help you build a 1m light painter which can support most common image formats. They’ve also helpfully included instructions on making your photos taken with this setup as bright and sharp as possible.


We’re wondering if we have enough time to build our own rig for Christmas. If you make your own, please post a link in the comments!


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A connected lamp to wake me up

via Dangerous Prototypes


Limpkin writes, “I’ve always wanted to play with these 10W RGB LEDs!
So for some reason I bought 2 IKEA lamps at a flea market. As IKEA furniture has a long history of being hacker-friendly, I figured they shouldn’t be an exception to the rule.
My plan? Fit a few 10W RGB LEDs in there together with an ESP8266 to use the final result as an alarm clock.”

Project info at Limpkin blog.

A new version of Scratch for Raspberry Pi: now with added GPIO

via Raspberry Pi

There are many excellent things to be found in last week’s release of Raspbian Jessie and we’ve been keeping one of the best ones tucked under our big Raspberry Pi-shaped hat. In the Programming menu on the desktop you’ll find a new version of Scratch, our favourite programming language for beginners.

Breadboard and Scratch on Raspberry Pi

Connect buttons, sensors, cameras, LEDS, goblin sticks and other gubbins to your Pi using Scratch

Tim Rowledge, who has been “vigorously wrangling Scratch into shape over the last couple of years” (thanks Eben), tells us what’s new:


Along with the new Raspbian release we are including the latest Scratch system update. It might have seemed a bit quiet on the Scratch front since March, but lots has happened here in the rainforests of Vancouver Island. There are two primary changes you will notice:

  • a significant increase in speed
  • the addition of a built-in GPIO server.

Speedier Scratch

One of the big projects last year was to modernize the Scratch code to run in a current Squeak Smalltalk system rather than the very old original version; this improved performance a fair bit all on its own, since the newer Squeak benefited from a lot of work over the years. [The Scratch world is created using Squeak, a dialect of the Smalltalk programming language, and Squeak itself runs on a software emulation of a computer system called a virtual machine -Ed.] It also built us a Scratch that could run on the very latest Squeak virtual machines that have dynamic code translation, generating machine code at run-time. Along with work to improve the Squeak code that implements Scratch, we then had a noticeably faster system.

A major project this year has been building such a virtual machine for the Pi; until now, only x86 machines have been able to run this version. With a very generous amount of support from Eliot Miranda – the original author of the Cog virtual machine and all-round software deity – the ARM Cog VM has been whirring away since around June.

Benchmarks are always a nastily slippery subject, but we feel that Squeak performance is typically between 3 and 10 times faster, obviously depending on what exactly one is measuring. Things will get even faster in the future as we iron out wrinkles in the code generation, and soon we hope to start benefiting from another project that does code optimization on the fly; early hints suggest at least a doubling of performance. Since Scratch uses a lot of graphics and UI code it doesn’t always speed up so much; but we already did a lot of graphics speed improvements for prior releases.

Our favourite “scary big demo” is Andrew Oliver’s implementation of Pac-Man. The original release of Scratch on the Raspberry Pi Model B could manage almost one frame per second, at best. The same Model B with the latest Scratch system can manage about 12-15 frames per second, and on a Raspberry Pi 2 we can get a bit over 30, making a very playable Pac-Man.


The new GPIO server for Pi Scratch is a first pass at a new and hopefully simpler way for users to connect Scratch to the Raspberry Pi’s GPIO pins or to add-on boards plugged into them. It is modelled on the mesh/network server and uses the same internal API so that either or both can be used at any time – indeed, you can have both working and use a Pi as a sort of GPIO server or data source. We have not introduced any new blocks at this point.

The server also allows access to the Pi camera, IP address and date and time and allows complex functionality. For example, the following scripts (along with a suitably configured breadboard) provide the ability to turn LEDs on and off according to a button, to take a photo with a countdown provided by a progressively brightening LED, and ways to check the time etc.

Examples of using Scratch to control the camera module, control LEDs connected to the Raspberry Pi's GPIO pins, and check the time

Examples of using Scratch to control the camera module, control LEDs connected to the Raspberry Pi’s GPIO pins, and check the time

Add-On Hardware

We can also plug in Pi add-on cards such as the Sense HAT, Pibrella, Explorer HAT, PiFace, PiLite and Ryanteck motor board.

Each card has its own set of commands layered on top of the basic GPIO facilities described above.

Demo project scripts

In the Scratch Examples directory (found via the File-->Open dialogue and then the Examples shortcut) you will find a Sensors and Motors directory; several new GPIO scripts are included, including the one above.


Closing notes from Clive

We’re really pleased that GPIO is now built in to the Pi version of Scratch. It means that users can use access the GPIO pins “out of the box,” and so get into physical computing that much more easily. We’ve also introduced the GPIO pin numbering system also known as BCM numbering for consistency across our resources, and having our own version of GPIO support gives us finer control over functionality and support for add-on boards in future.

All of our resources using Scratch will use this version from now on, and existing resources will be rewritten. Tim’s reference guide details all of the commands and functionality, and there will be a simplified beginner’s tutorial along this week.

Last of all, there’s no way I can end this post without taking the opportunity to thank our community who have supported (and continue to support) GPIO in Scratch on the Pi. In particular, a big thanks to Simon Walters, aka @cymplecy, for all of his work on Scratch GPIO over the last few years.

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