I’ve made a Cursed USB-C 2.0 device. It behaves differently based on the orientation of the plug. pic.twitter.com/8Ko66wPuV2March 21, 2021
Mechanical engineer Pim de Groot has built a profane object. Or, as he calls it, a “Cursed USB 2.0 device.” It’s an accurate name. For years, we put up with standard USB plugs that can only be slotted in in one direction. Due to some cosmic law, these USB-A cables always seem to require three attempts to plug in properly. USB-C was meant to be our salvation: a smaller, symmetrical plug that can handle data and video and work with basically any device.
I can’t think of anything more cursed than tainting USB-C with a board that betrays that symmetrical design. Pim de Groot is a mad genius.
The Cursed USB-C 2.0 device is actually a fascinating little object. It exists simply because de Groot was curious if it was possible. The key to the device is that while USB-C cables have a symmetrical shape, the electronics inside the cable aren’t exactly symmetrical themselves. “The plug only contains one pair of D+ and D- contacts,” de Groot explains in a tweet thread about his build. “The way this board works is that it has two SAMD11C microcontrollers, each connected to one pair of D+/D- contacts. One of them gets a connection and turns their LED green, the other doesn’t and stays red.”
It’s a funny single-purpose device, elegantly robbing USB-C of its greatest strength. In de Groot’s hands, USB-C is like a mouse with only one button. Or a toilet paper holder that only rolls under, not over. The cursed board isn’t actually doing anything nefarious—it’s just lighting up a different LED to cheekily show that it can tell which way your cable is plugged in—but just imagine the potential for evil here.
Normally, when you plug a USB-C cable into a USB 3.0 port, the USB controller is actually doing some quick processing to determine the orientation and then function properly. But de Groot casually suggested that it may be possible to write a USB driver that messes with that process, and instead of working the first time you plug it in… or when you flip it over… it only connects the third time, when you return to the original orientation.
USB-C 3.0 and up handles this by detecting the orientation in the controller and configuring some switches. It might be possible to make a custom driver or firmware to enable this.March 21, 2021
This would apply the cosmic law of USB-A to USB-C, just when we thought we’d escaped it. So far de Groot has only used his power for chaos. Let’s hope he never uses it for true evil. But in the meantime, some words of wisdom just in case your USB-C cable doesn’t seem to be behaving as it should:
“If you encounter problems with your USB-C devices you might want to try to flip the connector,” de Groot says. “Because while they told us the orientation of the plug doesn’t matter, it clearly does in some cases.”