Keyboard Builders' Digest / Projects
Cipulot's EC87 is an Electrostatic Capacitive (EC) TKL keyboard PCB.
Published April 22, 2022
According to designer Cipulot (@cipulot), his EC87, a fully open-source EC* TKL PCB is "working flawlessly". N-key rollover, analog actuation and QMK/VIA/VIAL compatible.
After some serious work, design, lack of sleep and productive VCs I can finally say it: IT WORKS!!!!! – Cipulot.
GitHub repo this way: https://github.com/Cipulot/EC87
- Layout size: tenkeykess (TKL) Compatible switches: EC switches (Topre and NIZ)
- Microcontroller: STM32F411
- Connector: detachable USB Type C
- Firmware compatibility: QMK (with VIA/VIAL support)
- Protection hardware: fused & ESD protection
About EC & Topre boards
I have to confess I've seen Topre and other boards with electro-capacitive switches (can we consider these as switches?) always as something obscure. Apparently enthusiast-level but still rubberdome? Full of springs but not mechanical?
The point is, I'm far from being an expert in this field so I reached out to Cipulot who seemingly keeps churning out EC PCBs.
E.g. the EC87 is not the first EC project of the author, but a continuation of his development of open-source EC boards after publishing the Corne EC Revival, revival of sekigon-gonnoc's CorneECWL.
So the wall of text below reflects almost entirely Cipulot's thoughts.
First and foremost, EC stands for Electrostatic Capacitive which is basically the description of what system is implemented to detect the key being pressed.
Topre is just one of the companies involved in creating EC boards.
Funnily enough, they are not a keyboard company but a die-cast and refrigerator company (that's where the Coldtop comes from) – Cipulot.
According to Cipulot, people at Topre dipped their toes into keyboard stuff when they started to look into terminal keyboards in the mid/late 70s. They developed the switch which is nowadays referred to as Topre switch, composed of the spring, dome, housing, and slider.
So Topre is EC but not every EC switch is Topre. In the scene, people tend to use this to mark the difference between NIZ [another manufacturer of EC switches – Ed.] and Topre but it goes much more into that. NIZ basically uses the same assembly (spring, dome, slider, housing, etc.) and shares the basic operational principle when it comes to detecting the key presses. But Topre and NIZ aren't the only ones that did EC-based boards. IBM actually used EC-based detection systems in both the Beamspring and Model F.
Another option for EC is the Varmilo EC switch series. They're quite interesting in the way that they incorporate the EC components, apart from the sensing circuit, inside an MX style housing and stem:
Usually, when we speak of EC we either mean Topre or the equivalent NIZ though.
Topre is the creator of the Topre switch and it's being used in third-party boards too (pretty much like how Cherry designs and produces the MX switches that are then used by third parties.
The Topre name itself is still a trademark, but the patent behind the switch technology (US4584444) expired years ago.
The "notTopre" logo added to the bottom of EC87 is more for memes, just like the THOCC drawing. It serves as a little hint that it works with the switch assembly that Topre developed but NIZ components can be used too (with a dedicated plate).
I try to avoid using full names of companies' stuff (even solely for showing compatibility) bc it doesn't always turns out well. This one being an open-source project, I want to avoid any problems – Cipulot.
Published on Fri 22nd Apr 2022. Featured in KBD #75 (source).
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