IR launches 600V LED control IC

International Rectifier has announced a new buck regulator control IC for driving LEDs at 600V, with full PWM dimming control.

The IRS2980 – the first entry in International Rectifier’s new series of LEDrivIR ICs – uses hysteretic average current control to precisely regulate the current across the full range.

The LED buck driver features low-side MOSFET drive with high-voltage internal regulator and high-side current sensing. The converter is compatible with electronic PWM dimming allowing for 0%-100% current control.

“In the rapidly growing solid state lighting sector, there is a need for low cost driver electronics to supply constant current output to high brightness, high power LEDs,” claimed International Rectifier’s Peter Green, the man in charge of the company’s LED group.

“The new IRS2980 offers improved performance at a lower system cost than alternative solutions for non-isolated LED driver applications,” Green concluded.

Pricing is set at $0.60 per IC in SO-8 packaging based on the purchase of 10,000-unit trays, with IR’s customers yet to announce retail pricing for makers who don’t need quite so many units.

A datasheet for the part is available as a PDF.

Linux 3.1 adds OpenRISC, WiiMote support

The Linux kernel 3.1 has been officially launched by project founder Linux Torvalds, and there’s one particular feature that should cause a stir in maker and hacker circles: support for the OpenRISC architecture.

As of Linux 3.1, support for the OpenRISC family of open source GPL-licensed processors is now built-in to the kernel, making it significantly easier to get software up and running on the chips.

While the OpenRISC hardware doesn’t rival processors from the likes of ARM, Intel or AMD for performance – current implementations of an OpenRISC 1200 design with 32KB of cache on a Xilinx ML501 achieve around 67 points on the CoreMark benchmark at 50MHz – it’s a promising project for anyone interested in microprocessor design.

In addition, support for Near-Field Communications – NFC, short range radio chips designed for inter-device communication in mobile applications – has been baked in, along with the ability to address a Nintendo WiiMote controller as a human interface device.

The new kernel is available now from Kernel.org.

Raspberry Pi founder releases prototype schematic

Raspberry Pi 2006 Prototypes, built in Veroboard and PCB

Raspberry Pi 2006 Prototypes, built in Veroboard and PCBEben Upton, co-founder of Raspberry Pi and creator of the eponymous $25 ARM-based microcomputer, has released schematics for the creation of an early prototype from 2006.

While the ‘Raspberry Pi – 2006 Edition’ lacks some of the power of its more modern counterpart – thanks largely to the use of an Atmel ATmega644 microcontroller running at 22.1MHz and a mere 512KB of SRAM, compared to the 700MHz ARM process used in the modern edition – it’s a lot easier to build at home.

“These boards use an Atmel ATMega644 microcontroller clocked at 22.1MHz, and a 512K SRAM for data and framebuffer storage,” Upton explains. “19 of the Atmel’s 32 GPIO lines are used to drive the SRAM address bus. To generate a 320×240 component video signal, the Atmel rapidly increments the address, and the data lines are fed via 74HC-series buffers to a trio of simple summing-point DACs; during horizontal and vertical blanking, it is free to perform other operations.”

The upshot: a microcomputer you can build from off-the-shelf components on Veroboard, capable of producing simple 3D graphics at a 320×240 resolution.

The below video, released by Upton, shows off the device’s capabilities, while the schematics and a PCB layout can be downloaded directly from Raspberry Pi.

Chip forging gang gets busted

US Federal officials have closed down VisionTech, a semiconductor reseller which is claimed to be responsible for the sale of thousands of counterfeit chips into industrial and military markets.

Although not well known outside the industry, ‘black topping’ is a technique whereby low-grade components are sanded down to remove the markings and then repainted with new markings claiming specifications – such as response times, radiation screening or longevity – that they simply do not have.

It’s a lucrative game – VisionTech’s particular swindle, which saw thousands of chips sent to military contractors, generated around $16 million in ill-gotten gains – but one which can leave lives at risk when re-manufactured consumer-grade components are used in medical, military or industrial systems.

For details on the case, along with methods of determining if a chip has been ‘black topped,’ VentureBeat has a great write-up.

The Rolson miniature hand drill

Rolson Miniature Hand Drill
Rolson Miniature Hand Drill
The Rolson Miniature Hand Drill.

If you work with PCBs, then the chances are good you’ll need to clear a blocked through hole or add a connection of your own. Billed as a drill for ‘precision’ work, the Rolson miniature hand drill is cheap but not so cheerful.

The first thing that strikes you about the Rolson drill is that it’s made of moulded plastic. That is, the entire thing with the sole exception of the brass adjustable chuck, which will accept any size bit up to around 0.9mm – although we managed to cram a 1mm bit in there without too much difficulty, until it was time to remove it again.

The moulding lines and scarf are plain to see. At no point has it occurred to Rolson to remove them during the manufacturing process, and that’s a problem: the rotation is uneven and juddery, increasing the chances that your ‘precision’ work is going to go wrong at some point.

Rolson Miniature Hand Drill - Rear
The build quality is extremely low.

That’s not to say that it doesn’t work: during testing, we were able to clear several holes blocked with broken-off component legs on multiple PCBs, and add a few new holes of our own. Each took only a minute or so of careful drilling, but it wasn’t a comfortable process.

The Rolson miniature drill isn’t without certain plus points: compared to other PCB drills it’s cheap, and a removable cap in the handle is a useful place to store spare bits if you don’t mind them rattling about.

It could have been so much better, however. With a little effort, a larger adjustable chuck – we’d like to see it accept bits of 1.5mm at least – and a more painstaking manufacturing process, the Rolson miniature hand drill could have been an essential toolbox companion. As it is, it’s more of a disposable one-shot when you can’t find anything better to use.

Pro: It mostly works.
Con: It probably won’t do so for long.
Supplier: Maplin, £5.29
Score: 3/9

The RHT03 digital temperature and humidity sensor

RHT03 Digital Temperature and Humidity Sensor
RHT03 Digital Temperature and Humidity Sensor
Accurate but expensive - the RHT03.

While the use of analogue sensors for detecting temperature are common in the world of open source electronics, digital devices are less so. The RHT03 could help change that, offering a low-cost high-accuracy sensor which connects easily to most prototyping platforms.

The first thing to notice about the RHT03 – also known as the DHT-22 – is its breadboard-friendly layout. Mimicking a T-style package, the legs are properly spaced for connection to any common breadboard type, while also allowing for the component to be soldered to a through-hole PCB for a more permanent project.

Sadly, the RHT03 is clearly made on a budget: the legs are extremely thin, and it can be fiddly to get the breadboard to accept the component without bending one or all. If you’re using the RHT03 in a project where it’s going to be frequently moved around, consider adding some reinforcement.

The RHT03 is an odd beast: although digital, it’s not a One-Wire device and doesn’t work with any common libraries. Thankfully, resourceful hackers have fixed that problem: a GitHub project page provides a simple library for the component plus sample code which spits out the current temperature and humidity.

There are limitations, however: query the RHT03 too quickly and it will return an error, something which is never a problem with an analogue sensor. That restriction – due to the digital nature of the device – comes with an corresponding upside: unlike a thermistor, there’s no complex calculation to carry out in order to arrive at a human-readable figure.

Connecting the RHT03 to an Arduino and running the sample script results in two figures: temperature in Celsius and humidity as a percentage. Using a calibrated multimeter with K-type temperature probe proved that the temperature was accurate, and the humidity didn’t seem far off. Accuracy is official stated as ±0.5°C and ±2% RH.

Compared to using two separate components, the RHT03 has a dual advantage: the sensors are located together for better accuracy, and it requires only a single input pin on your controller along with VIN and ground connections. It’s also battery-friendly, drawing around 1.5mA when reading and 50µA when in standby mode.

If you’re using a non-Arduino prototyping platform, the RHT03 will likely still work – thanks largely to a wide supply voltage range of 3.3-6V – but you may find yourself doing a bit of hacking in order to implement the DHT22 communications library.

There is a catch in all this, however: at £8.51, the RHT03 is an extremely expensive option compared to analogue sensors. If you need accuracy, it’s a good option, but be prepared to pay for the privilege.

Pro: Accurate temperature and humidity readings from a single pin.
Con: Very expensive compared to analogue equivalents.
Supplier: Proto-Pic, £8.51
Score: 6/9

The Arduino ProtoShield v5

ProtoShield v5 Clone
The breadboard fits perfectly on the ProtoShield.

Arduino ‘shields’ – add-on boards that connect to the Arduino’s headers to add additional capabilities – are handy things, but sometimes you need something a little more custom. Although it’s possible to make your own, the Arduino’s famously non-standard pin spacing makes it difficult, but there’s a solution: the ProtoShield.

As its name suggests, the ProtoShield is a shield which makes prototyping on an Arduino significantly easier. Often supplied in kit form, the ProtoShield’s design is open source. As a result, it’s possible to get the device pre-made from a variety of sources, which sadly means you’re often taking a gamble on quality unless you buy directly from a reputable supplier.

The shield on test, unfortunately, is from no such source: manufactured by an unknown Chinese OEM and sold through Hong Kong gadget site DealExtreme, the design is based directly on Adafruit’s implementation of the ProtoShield with the logo removed before the PCB has been printed. That’s in direct contravention of the Creative Commons licence under which the open source design is provided, and we’d recommend you look elsewhere if you’re planning on buying one.

The shield itself arrives as two separate components: the ProtoShield, plus a mini-breadboard with an adhesive pad on the underside. This breadboard is specifically designed to fit on top of the ProtoShield, allowing you – if you so choose – to combine the two into a portable prototyping platform.

The other option is to use the mini-breadboard on another project, and concentrate on the ProtoShield itself. The PCB is covered in through-hole soldering points, and a glance at the underside reveals a combination of connected and disconnected circuit paths. There’s room for a wireless module, an SOIC solder pad, and in addition to the usual Arduino headers there’s an additional five for ground and 5V on many designs.

The concept is simple: prototype the layout of your custom shield’s components with the breadboard, and when you’re ready solder the components in place directly onto the shield to create a permanent custom creation. It’s a neat idea, but there’s a problem: the ProtoShield isn’t cheap. Even as an unlicensed knock-off shipped from China, the ProtoShield will set you back around £7, which compares poorly with some stripboard and a set of angled headers.

As a prototyping platform using the stick-on breadboard, however, the ProtoShield is great. If your project calls for LEDs, you’ll be pleased to see two already form part of the shield’s design, along with a handy switch. The fact that the reset switch is brought to the top is also a welcome sight, as many shields forget how inaccessible the Arduino’s version can be when the shield is in place.

Pro: It’s a great portable prototyping platform when combined with the breadboard.
Con: While easy, it’s an expensive way to make your own shields.
Supplier: DealExtreme (uncredited clone of Lady Ada’s ProtoShield)
Score: 7/9

BoKlok designer warns of waning hacker culture

BoKlok housing

If you’ve spent any time in Sweden, you’ve likely seen Inter Ikea’s BoKlok prefab housing developments. You may not have realised, however, that the concept comes from a British Mini enthusiast with a love of hacking.

David Morton, lead architect for BoKlok UK, is responsible for the clever design touches that allows buyers of the prefab structures from Inter Ikea – the housing arm of everyone’s favourite flatpack giant – to construct the buildings in a fraction of the time of a normal house, and credits his love of the original Mini and taking things apart for his inspiration.

In an interview over on Humans Invent, Morton claims that the past few generations have lost the hacker ethic that drove his youth, with kids more interested in the instant gratification of games and films than the joy of taking something apart to see how it works.

“Working with your hands, building things – architecture is a bigger version of it,” Morton claims. “I think a couple of generations have lost out in the satisfaction of making something and fixing something.”

While Morton may have a point, the growing popularity of hacking and making groups in the UK – including an increasing number of collaborative working spaces dubbed ‘hackerspaces’ where groups of like-minded individuals can help each other out on a variety of projects – suggests that the tide is turning.

Building stripboard prototyping modules

Robotics enthusiast and Arduino hacker June Jones has posted a guide to creating a infrared sensor module for a line-following robot which also serves as a handy guide to building homebrew sensor modules for any prototyping system.

While the guide, published over on Instructables, starts off with the familiar sight of a breadboard and an Arduino, once the initial prototyping is complete Jones demonstrates how to turn a breadboarded design into a tiny module using stripboard.

Although not as impressive as a professionally etched PCB, stripboard is handy stuff: Jones shows the design shrinking from a hefty breadboard down to a tiny module which can be plugged in to any Arduino-like prototyping system with ease.

If you’ve ever wondered how to take a breadboard concept to the next level, you could do a lot worse than follow the guide – even if Jones does admit that the stripboarded version stopped working after a short while due to a component fault.

Stories in analogue IC design

If you’ve ever considered the insides of those magic black boxes at the heart of many electronics projects, then you’ve likely thought that they must be beyond the ken of mere mortals.

Don Sauer’s site Idea2IC looks to change all that, with a series of fascinating tales from his 30 years in the analogue and mixed signal integrated circuit design business.

From his first sixteen-pin IC design – the LM13700 stereo transconductance amplifier, “designed by Bill Gross and myself in less than 5 minutes” – to more modern creations, Sauer’s site is a goldmine of tips, tricks and fascinating anecdotes.

For those looking to make the leap into IC design, Sauer’s Spice simulations are well worth a look. For everyone else, just marvel at the thought process that gives birth to those little black and silver bugs.