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Type-C hot plug detection
- 2021-02-24-

Type-C hot plug detection

Type-CThe hot plug detection is achieved by detecting the status of CC1 and CC2. As shown in the figure below, the Type-C interface shown in interface 1 is the power supplier, and there are Rp pull-ups on CC1 and CC2 of the interface. The Type-C interface shown in interface 2 is the power consuming side, and there are Rd pull-downs on CC1 and CC2 of the interface. The CC1 pins at both ends of the normal Type-C cable are connected and open, and CC2 is disconnected (CC2 is used to realize the Vconn power supply function).

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When interface 1 and interface 2 are connected through a Type-C cable, interface 1 will detect that CC1 or CC2 has a pull-down resistor due to the existence of positive and negative insertion, and it is considered that the device is plugged in. Similarly, when interface 2 detects that there is a pull-up resistor on CC1 or CC2, it is considered that the device is inserted. Subsequently, interface 1 will switch the state machine. When the states of CC1 and CC2 are stable and meet the time requirements of the state machine (please refer to the Type-C specification document for the state machine), interface 1 will provide 5V to VBus and consider it connected success. In the same way, after the state machine of interface 2 detects that CC1 and CC2 are stable and VBus has power, the connection is considered successful.

When the connection between Type-C interface 1 and interface 2 is disconnected, interface 1 will detect that the pull-down resistor of CC1 or CC2 is removed, and it is considered that the Type-C connection is disconnected. In the same way, when interface 2 detects that VBus is out of power or the pull-up resistor of CC1/CC2 is removed, it is considered disconnected.

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