As counter intuitive as the age-old adage seems, sometimes less really is more.
If you still need convincing of the sage wisdom, consider life before the internet, before even the telephone was an everyday bit of equipment - way back to the times when a far simpler method of communication was commonplace — the telegraph.
Some of the most historic events known to humankind have been signaled out using just one key - from the somber signal for help from the sinking Titanic, to the more light hearted inquiry sent from George Orwell to his publisher, inquiring of the success of his new book. The message, a single "?", was returned by his publisher with yet another single character message - "!".
That's the sort of progress update meeting we'd all be lucky to have!
Glen Akins (@bikerglen) was perhaps inspired by this idea, or just wanted to see how simple a USB-HID device can be. With all the c̶h̶e̶a̶p̶l̶y̶ ̶d̶e̶s̶i̶g̶n̶e̶d̶ highly cost-optimized USB-HID gadgets available, including many that have a somewhat... "wonky" idea of the USB spec, it's with open arms that we welcome the One Key HID device, serving as a solid reference for anyone looking to implement the HID spec for their own uses and needs!
It's as simple as it looks! Based around a Microchip PIC16F1459 MCU, there are barely a handful of components used to complete the construction of this crazy contraption, from the custom 3D enclosure containing it, to the Cherry MX switch that closes the circuit.
With the PIC mounted on the custom-designed Perfect Purple PCB from OSH Park, the only other parts to this build are the case and a collection of nuts and screws.
This is a project that lends itself to even the novice builder, with some generously sized components on the board, that make it possible to assemble even with drag soldering — no reflow oven needed here!
Perhaps more interestingly is that, if you want to extend this idea to maybe get a bit more... "freaky" with HID, well, Akins has you covered — he's even gotten a bit freaky himself, extending this project to his Three Key keyboard.
Now, instead of having to pick and choose which command you'd like mapped to your mono-keyed HID device, you can get a triplet of tactile feedback touch-based interactions in one, simple-to-build device!
If you want a bit more feedback from your PC, maybe you're in the market for this pint-sized PIC powered device, based around the same core MCU and schematic design — the difference being here that instead of reading in the status of a switch, this pod pushes information back to the user, with everybody's favourite feedback device that we all know and love, a WS281x compatible digital RGB LED.
The core device is still the same, only the flow of data is reversed, and the footprint popped out, to allow for the differing arrangement PTH holes required for the LED.
We can't help but think that the board could maybe be designed with two, co-located footprints, or maybe even with some SMD smart LED parts, that could potentially pave the way for some hybrid devices. Backlit, translucent-cased Cherry MX switches, complete with suitably clear matching keycaps could make for some really visually compelling devices.
With such a barebones BoM, this really is a cost-effective way to add some extra fun and functionality to your next projects feature list, and if you've creative with your code and construction skills, this project surely will serve as an exceptional springboard for shoehorning some extra functionality into your computers USB ports — Akins showcases this in style with his take on the USB Jog Wheel, which in his words, "is less useless" than the aforementioned Cherry switch / LED boards.
I feel that depends on perspective, and rather than "less useless," I'd say is a beautiful worked example of product design. I can see some strong use cases for all of these devices, but Akins obviously has specific uses cases in mind that give a different grading system!
The only device I can see less use for would most likely have been the USB Caps Lock Key HID Buzzer, which builds again on this proven PIC HID platform. Instead of pulsing out soothing patterns on that PTH LED or communicating the clickety-clacks of that Cherry MX switch, however, this little box of beeps lets you bleep out your signals through the use of it's onboard buzzer! I personally have my PC muted nearly all of the time, and it's been a long while since I've heard an onboard sounder on any machine of mine, but I can see some potential prank value in hiding it away, connected to a colleagues computer, with an accompanying application to let me control the contraption remotely.
Otherwise, the Japanese market might be very keen to have hands-on of a device that can dish out the nostalgic dial tones of communication mediums of days past, or play that familliar set of notes that we were once greeted with on booting up our boxes.