Want to take Raspberry Pi OS out on the road with you? In celebration of #MagPiMonday, we’re taking a look at Ken Van Hoeylandt’s handheld PC, which features in the latest issue of The MagPi.
When Ken Van Hoeylandt was growing up, computers were big, bulky machines. But by the time he was a teenager in the 1990s, they were shrinking fast, leaving Ken desperate to get his hands on some of them.
“I was attracted to the idea of being able to carry a computer with me all the time,” he says. “I owned a Palm III and wrote some simple software for it, eventually giving it internet access over a serial cable at home. Later, I upgraded to a Sharp HC-4500; a Windows CE handheld PC with a colour screen and more capabilities.”
Over the years, Ken’s passion for handhelds has remained and he’d been keen to rekindle his love for them. “It’s partially nostalgia and partially the freedom of having the power of a regular OS,” he explains. “These days everyone has mobile phones and tablets, but they take away a lot of the control that you used to have.”
How small?
Recently, after considering getting his hands on Clockwork’s uConsole, a modular pocket-sized computer, he felt that building his own handheld was more challenging. Snapping up a Raspberry Pi Compute Module 4 (CM4), he also vowed to take advantage of its quad-core ARM Cortex-A72 processor by putting it at the heart of his own homemade device.
“I chose Raspberry Pi because of the support it has and how easy it is to use,” Ken says, revealing he’d considered a Raspberry Pi Zero 2 W computer but felt he’d miss out on many connectivity options. “Raspberry Pi Zero 2 W would have resulted in a smaller handheld computer but, for a device that would be a daily driver, the user experience is the most important aspect above everything else.”
To that end, Ken made some more crucial decisions. “I initially considered creating a foldable device, but making it thin enough to my liking would have been too hard for me to achieve,” he explains. “Foldable devices require good hinges, and I suspect that it’s very hard to make without expensive machinery like a micro mill setup.” Instead, his device has the screen above the keyboard.
Key to success
The biggest challenge was the case design. Ken created the CAD files for the 3D-printed shell using Onshape, and he wanted it to be as compact as possible. He had to consider the layout of the components so that the wiring would be logical. “You don’t want to put wires from one side of the case to the other and then back again,” he adds. He also needed to consider cooling.
“There’s limited space for a fan, and multiple components generate heat,” he continues. “In other words: there are very few layout variations that work well, and you also have to take into account that everything needs to fit in place and be easy to assemble. When you make a change in a layout to improve wiring, it might affect airflow. It becomes a very interesting tech puzzle.”
Even so, the casing works well. Time is now being spent making the keyboard better. “It’s pretty bad,” Ken confesses. “It’s built like most TV remotes and you have to press it fairly hard to have it work consistently – fine for entering a Bash command or two, or perhaps a URL once or twice, but you don’t want to use it to type lengthy emails or have a chat with someone.”
It’s why the next iteration of Decktility will have a fully custom keyboard with microswitches, but it’s not the only changes being considered. “I’m currently using Raspberry Pi OS, but I might tinker with Kali Linux or Parrot OS in the future,” Ken says. “I’ve also been curious about software-defined radio (for example, RTL-SDR), so I might play with that at some point too.”
The MagPi #132 out NOW!
You can grab the brand-new issue right now from Tesco, Sainsbury’s, Asda, WHSmith, and other newsagents, including the Raspberry Pi Store in Cambridge. It’s also available at our online store which ships around the world. You can also get it via our app on Android or iOS.
You can also subscribe to the print version of The MagPi. Not only do we deliver it globally, but people who sign up to the six- or twelve-month print subscription get a FREE Raspberry Pi Pico W!
The free PDF will be available in three weeks’ time. Visit the issue page for more details.
