It is a rare sight to see a proper strain relief on a cable these days… Strain reliefs on connectors are often fairly abhorrent when they do exist, and at most times they don’t even exist. Posted in Microcontrollers, Tech Hacks Tagged cursed devices, USB C Post navigation (Heading image: Cursed USB-C 2.0 Device, by Pim de Groot) Board view of ’s Cursed USB-C 2.0 Device. While at first glance this seems little more than a fun party trick, but it also offers insight in a possible failure mode of USB-C 2.0 devices where only one plug orientation works, due to broken traces or pads. With a bit more circuitry it’s possible to detect which way around the plug is inserted and use this information in a single MCU system, altering its behavior. Normally you would connect the matching lines in these pairs together to ensure consistent behavior no matter the plug orientation, but you don’t have to.īy leading each USB 2.0 data pair to its own SAMD11C MCU, only one of the MCUs would be connected to USB, resulting in the connected MCU blinking the LEDs. The reason for this behavior is simple: as explains, although the USB-C plug has only a single pair of data lines (D+/-) for USB 2.0 connectivity, the receptor duplicates these on either side of its pins, leading out two pairs of D+/- lines. Sigil on the back of the cursed USB-C 2.0 device, by Pim de Groot. Only one orientation of the USB-C plug will cause one of the LEDs to light up green, with the other orientation leaving both LEDs blinking red. He made a PCB that elegantly demonstrates the simplicity of the problem, featuring two LEDs.
As shows with a ‘ Cursed USB-C 2.0 Device‘, reality is a bit more complicated when it comes to USB 2.0 compatibility in USB-C.
One of the selling points of the USB-C plug is that supposedly there is no way to incorrectly insert it.
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