Custom PC, Issue 166

Custom PC Issue 166Readers of my regular Hobby Tech column this month will find a BBC micro:bit-driven tutorial alongside two reviews covering the remarkable Raspberry Pi Zero W microcomputer and the fascinating Delete by Paul Atkinson.

The idea for the tutorial came about while working on a chapter of my upcoming¬†Micro:bit User Guide, and seemed like a perfect fit for the readers of Custom PC Magazine: turning the low-cost yet extremely flexible micro:bit into an addressable USB-connected 5×5 LED matrix and having it display current CPU load in a constantly-updating bar graph. Naturally, the same technique could be used to graph almost anything.

The secret lies in MicroPython’s REPL, an interactive interpreter which can run on the micro:bit and accept commands via the USB serial port. By switching the micro:bit into REPL mode, it can be slaved to another system over USB. The result: the entire program code, written in Python using the serial, time, and psutil libraries, exists¬†purely on the host machine. A quick bit of Blu-tack later, and my monitor was wearing a CPU monitor which worked even when the display was off.

The Pi Zero W, meanwhile, was a device to which I had been looking forward for quite some time. An upgraded version of the original £5 Raspberry Pi Zero microcomputer, the Pi Zero W differs in only one respect: it has a built-in radio module, the same BCM43438 as found on the far larger and more expensive Raspberry Pi 3.

While the addition of the radio module, which offers Bluetooth, Bluetooth Low Energy, and 2.4GHz Wi-FI connectivity, almost doubles the price of the Pi Zero W to ¬£9.60, it’s money well spent. In almost every Pi Zero project I have built, I’ve ended up using a USB OTG adaptor and low-cost USB Wi-Fi dongle to add network connectivity, and having it on-board – even at a slightly higher cost compared to a USB-connected solution – makes life considerably easier.

Finally,¬†Delete. Billed as “a design history of computer vapourware,” Paul Atkinson’s coffee table book is packed with high-quality photographs – and, for the rarer machines, the occasional rescaled JPEG exhibiting unfortunate compression artefacts¬†– covering machines from an upgraded Sinclair QL to a bright yellow IBM that never left the drawing board. Each comes with pages on its history, with interview subjects detailing features and failures alike, and while not all machines were strictly vapourware few are likely to have a place in the average vintage computing collection. In short: if you like old computers you’ll like¬†Delete, which is available now from Amazon and other bookstores under ISBN¬†978-0857853479.

As always, you can read the whole column and a whole lot more by picking up Custom PC Issue 166 from your nearest supermarket, newsagent, or electronically via Zinio and similar services.

Custom PC, Issue 165

Custom PC Issue 165This month’s issue of Custom PC Magazine marks a milestone: four years since I started writing my Hobby Tech column. To celebrate, three reviews spanning its five pages: the Ryanteck RTk.GPIO, the Kitronik Micro:bit Inventor’s Kit, and the Pimoroni GPIO Hammer Header – the only piece of electronic equipment I’ve ever reviewed installed with a hammer.

First, the RTk.GPIO. The brainchild of Ryan Walmsley, interviewed back in Issue 129, the RTk.GPIO is designed to bring all the joy of the Raspberry Pi’s general-purpose input-output (GPIO) header to any PC with a free USB port. A surprisingly sizeable red-hued circuit board, the RTk.GPIO includes a Pi-compatible 40-pin GPIO header with pin-out on the silkscreen. A quick¬†pip install of the Python library later, and you can pretty much take any RPi.GPIO program and have it run natively on your Windows, Linux, or macOS machine.

Perhaps the biggest power of the RTk.GPIO is in assisting with the development of software for Pi add-ons, using the extra computing power of a desktop or laptop to make your life easier then allowing you to transfer your program to a real Raspberry Pi with minimal changes once complete. Its only real downside, in fact, is price: it’s more expensive than picking up a Raspberry Pi Zero and turning it into a USB device, though undeniably smoother to use.

The Kitronik kit, meanwhile, is one of a range of add-ons I’ve been playing with for my upcoming¬†Micro:bit User’s Guide. Based around a GPIO expansion board for the micro:bit’s edge connector, the kit comes with mounting plate, solderless breadboard, jumper wires, and all the components you need to work through the included full-colour tutorial book – plus, in the version I picked up, the micro:bit itself, though the kit is also available without for those who already have the BBC’s miniature marvel.

In the years I’ve been playing with hobbyist electronics, I’ve seen these kits go from the most hastily thrown together things to extremely polished collections of hardware – and Kitronik’s kit definitely sits at the right end of that spectrum. There are nits to be picked, such as the lack of a handy plastic parts box for storage and no use of the lovely breadboard overlay sheets that make the Arduino-centric ARDX kit so easy to use, but it’s hard to imagine someone buying the Kitronik kit and being disappointed.

Finally, the GPIO Hammer Header. I’ve long been a fan of Pimoroni’s products, but the Hammer Header is by far both the simplest and the smartest I’ve seen. Designed for anyone who has purchased a Raspberry Pi Zero and wants to make use of the unpopulated GPIO header but who doesn’t fancy firing up a soldering iron, the kit makes use of cleverly-shaped pins which can make a suitable electrical connection purely mechanically.

The kit gets its name from the acrylic jig used for installation: assemble the jig with the Pi Zero in the middle, then give it a few sharp raps with a hammer to push the pins home. Male and female variants are available, allowing you to quickly install headers on both the Pi Zero and compact pHAT add-on boards, and to my surprise both installed quickly, easily, and without a single poor joint – and in a fraction of the time of soldering all 40 pins by hand.

For all this, and more, pick up the latest Custom PC Magazine from your nearest supermarket, newsagent, or digitally via Zinio or similar services.