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How does usb device with type-c receptacle detects, that plug (just bare usb type-c plug, without cable, and resistors) is attached?
Does USB specification describe this possibility?
I know, that my phone(sm-520f) somehow detects plug insertion, because I'm able to read MUIC registers, and it changes upon plug insertion.
Note: This question is NOT about CC pin detection sequence.
USB Type-C connectors have 4 pins for ground, and 4 pins for VBUS. By specifications, all similar pins must be connected together on PCB. Same requirement is for Type-C plug, VBUS pins and GND groups must be tied together "when mounted onto PCB".
However, it is possible to free one of pins (in VBUS or GND group) on mainboard and use it to check whether it is tied to the rest of pins or not. When "mounted plug" (not "raw plug") is plugged in, the host will be able to detect this. Technically this will be a slight violation of the letter of USB Type-c specifications, but who cares?
