Custom PC, Issue 150

Custom PC Issue 150There’s a bit of a theme to four of the five pages that make up this month’s Hobby Tech column, and with little surprise: I’ve been focusing on the Raspberry Pi Zero, that remarkable ¬£4 microcomputer which is still proving impossible for retailers to keep in stock. That’s not to say it’s entirely Pi-themed, though: I found room for a look at the lovely CodeBug, too.

Naturally, the first thing I had to do when the Raspberry Pi Zero Рa fully-functional Raspberry Pi microcomputer, equivalent in specification to the Raspberry Pi Model A+ but with twice the RAM at 512MB and a new 1GHz stock speed for the BCM2835 processor. The fact that the Raspberry Pi Foundation was able to pack all that into a device around half the footprint of the already-tiny Model A+ is impressive enough, but with a retail price of just £4 the Pi Zero is nothing short of revolutionary.

Sadly, my hope that stock issues would be cleared up by the time the issue hit shop shelves proved unfounded: while stock has appeared at the official outlets several times since the Pi Zero launched, it has immediately sold out again – making the device difficult to get hold of and leaving the market rife with sandbaggers flogging the ¬£4 device for anything up to ¬£50 on auction sites. My recommendation: be patient, keep an eye out the official outlets, and don’t reward the sandbaggers with your custom.

With the Pi Zero in hand, I figured a tutorial would be a logical next step. Perhaps one of the most impressive demonstrations of the new form factor’s flexibility comes in turning it into a true random number generator (TRNG) – at least, what Broadcom claims is a TRNG – for a USB-connected server or PC, improving security for a tenth the cost of the nearest off-the-shelf TRNG. While I used the simple method of attaching a USB-to-TTL serial adapter to the Pi Zero’s GPIO header, it’s even possible to create the same device with a single USB cable for data and power by replacing the stock kernel with one tweaked for USB OTG use – a cost-saving trick for another column, perhaps.

Finally, the CodeBug. I’d been planning on reviewing this for some time, but getting my hands on a sample proved tricky until oomlout was kind enough to loan me a unit from the device’s original crowd-funding campaign. Designed for educational use, and the inspiration for the BBC’s much-delayed micro:bit, the CodeBug is a microcontroller with on-board inputs and outputs and a built-in battery connector. Programmed using a modified version of the block-based Scratch language, it’s a great tool for teaching basic computer concepts – and I now have my hands on a few upgrades for the device, which will be appearing in a future issue.

All this, plus a bunch of stuff written by people who aren’t me, can be yours with a trip to any good newsagent, supermarket, or from the comfort of wherever you’re reading this via Zinio and other digital distribution services.

Linux User & Developer, Issue 160

Linux User & Developer Issue 160In this month’s Linux User & Developer, following my regular four-page news spread, you’ll find a review of a device that’s a little out of the ordinary: the NeuG, a true random number generator (TRNG) which costs a remarkably small amount.

When you’re using cryptography, you’re chewing up your system’s supply of randomness – or entropy. Linux, in common with other operating systems, works to fill its entropy pool by sampling a variety of things: traffic coming in on the network port, where you’re pointing the mouse and how fast it’s moving, and even how long it takes you to press particular keys. That’s all well and good for a desktop, but for a headless server it can take a while to fill a depleted entropy pool.

Coupled with the fact that it’s very difficult for a computer to produce¬†truly random output, there’s a market for true random number generators. These devices typically cost a small fortune but use a variety of techniques – ranging from physically breaking down pieces of hardware with high voltages and measuring the resulting changes to pointing a webcam at a lava lamp – to generate a constant stream of high-quality entropy.

Enter the NeuG, which was kindly supplied for test by the Free Software Foundation. While it looks like a flash drive that has lost it’s casing, the device is actually a miniature computer in its own right. Using on-board analogue sensors, the NeuG can generate what is claimed to be a stream of true random numbers – numbers which are then pushed through a conditioning hash and spat out of a virtual serial port. Simply link the NeuG to something like the rngd entropy gathering daemon, and kiss goodbye to entropy exhaustion in even headless or virtualised environments.

I have been extremely impressed with the NeuG, especially given its low $50 cost. While there are cheaper alternatives – such as using a $5 Pi Zero and USB TTL serial adapter to create something similar using the BCM2835’s on-board hardware random number generator module – the NeuG’s free nature, whereby the design and source code are all available for review and modification, make it a great choice where certified security isn’t a requirement.

For the full run-down, including benchmarks, you can pick up the latest issue of Linux User & Developer from your nearest newsagent, supermarket, or electronically via Zinio and similar digital distribution platforms.

The MagPi, Issue 40

The MagPi Issue 40This month’s MagPi, the official magazine of the Raspberry Pi Foundation, is just a little bit special: it is, to my knowledge, the first magazine ever to include a cover-mounted computer. The release of the magazine today also represents the launch of a brand-new Raspberry Pi model: the Raspberry Pi Zero.

I’ve been lucky enough to have been playing with the Pi Zero for some time, having worked on three of the hardware projects you’ll find between the covers of this extra-special issue. After peeling the Pi Zero from the cover, readers will be shown how to solder general-purpose input/output (GPIO) headers onto its otherwise extremely flat face, connect its serial port to a computer for use as a true random number generator (TRNG), and use it with an existing HAT add-on to act as a mood lamp.

The three projects I created for this issue were chosen from a long, long list. The Pi Zero is an exciting device: it features the same specifications as the Raspberry Pi Model A, but in a brand-new form factor a fraction of the size of the original. Naturally, some features have been cut: just like the Model A there’s no Ethernet chip, but there are also no CSI or DSI connectors and no analogue audio or video ports – though composite video is broken out to a solder pad for the adventurous. The ports that do remain have also been modified: the full-size HDMI port is replaced by a mini-HDMI, and the full-size USB port is a micro-USB port which requires a USB On-The-Go (OTG) adapter before it can be connected to standard USB peripherals.

In doing this, the Foundation has created a device that excites me even more than the full-size models. With a production cost so low that it can be cover-mounted on a high-street magazine, it’s now possible to put a full Linux computer in more project than ever before – and with a simple low-cost USB OTG adapter and a Wi-Fi dongle, it can be networked for a total outlay of well below $10. It is, in short, a game-changer, and I look forward to working on many more Pi Zero-related projects in the near future.

If that wasn’t enough, you’ll also find my review of the Tenma 60W Digital Soldering Station which has been my trusty companion in various projects over the last couple of years. It’s always nice to be able to give a device a good, long-haul test before drawing your conclusions and I’ve certainly put the miles in on the Tenma.¬†As I warn in the review a hobbyist doesn’t strictly¬†need a soldering station, but it does make life easier – and the low cost of this unit, purchased from CPC, makes it easy to recommend for those who fancy an upgrade.

All this, plus more – and, remember the cover-mounted Pi Zero – is available in your nearest WH Smith. The magazine itself is also available as a DRM-free PDF download from the official website, licensed under Creative Commons terms, but obviously you’ll have to buy a Pi Zero separately if you want to follow along with any of my projects.