Digisparks are very useful if you want to simulate a mouse or a keyboard. You can use them to play keyboard or mouse makros and also simulate other usb devices. But they have a few disadvantages, the biggest being the simplified usb plug which is just some tracks on the pcb. They don’t stay in place very well and are prone to losing contact from time to time so if you need something that stays in place and does its job they aren’t helpful. They also have all pins of the ATtiny85 available to hook up additional hardware but often that is not needed and just a waste of space. The next problem is their size: They are very small but still wide enough to block adjacent USB ports…
My goal here was to create a device that has the same functionality but without the listed downsides. I often don’t need additional hardware so I omitted the pins alltogether and since mine will always be powered by USB I can also omit the voltage regulator for the VIN-pin. I designed a board that is small enough to not block other USB ports and my version gets a proper USB plug which makes it a bit longer but also a lot more reliable. I used the original schematics to create my version since it works very well, and designed a tiny pcb around them – as always using KiCad. And just like I did in the Fan Controller project, I added both the 150 and 200 mil footprints for the ATtiny.
I could possibly have made this even smaller and I might do that in version two, but then it wont be possible to hand-solder it anymore and I will have to get that done, too. For now though this version is definitely small enough for my needs and very rigid with the proper USB plug to hold it in place.
To get the whole thing work like a Digispark the ATtiny85 needs to be flashed with the Micronucleus bootloader and the right fuses set, preferably before soldering it in. Version 1.11 is the one running on the Digisparks and makes it possible to flash my version through the Arduino IDE just like the original one.
Feel free to use my gerber files to order your own boards!
Here’s a few pictures of the assembled device and also a comparison to a Digispark:
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