What interface is the Xiaomi charger?

Xiaomi charger has a type-c interface, which is a brand-new USB interface form and a hardware interface specification for Universal Serial Bus (USB). It can be applied to both PC (main device) and An interface type that can be applied to external devices (slave devices, such as mobile phones). The biggest feature of the Type-C interface is that it supports insertion in both front and back directions, officially solving the worldwide problem of "USB can never be plugged in correctly". It can be plugged in either way.

#The operating environment of this tutorial: Android 13 system, Xiaomi 12 mobile phone.

Xiaomi charger is called type-c interface, which is a new USB interface form.

Type-C is a new USB interface form, which is smaller than Type-A and Type-B. It is a hardware interface specification of the Universal Serial Bus (USB); it can be applied An interface type that is applicable to PC (master device) and can be applied to external devices (slave devices, such as mobile phones).

Type-C was born with the latest USB 3.1 standard. Released by the USB-IF organization in August 2014, it is a brand-new interface developed by the USB standardization organization to solve the long-term disadvantages of USB interfaces such as inconsistent physical interface specifications and the only one-way transmission of power. It integrates charging, display, and data transmission. functions in one.

The biggest feature of the Type-C interface is that it supports insertion in both front and back directions, officially solving the worldwide problem of "USB can never be plugged in correctly". It can be plugged in either way.

Type-C port has 4 pairs of TX/RX lines, 2 pairs of USBD/D-, a pair of SBU, 2 CCs, and 4 VBUS and 4 ground wires

Type-C also provides 2 CC wires and 2 SBU wires. The CC line is mainly used for communication with the Power Delivery module (hereinafter referred to as PD). The CC line is first used to determine the direction of device insertion: forward insertion or reverse insertion. If it is forward insertion, the host uses CC1 to communicate with the device, and reverse insertion uses CC2. , you can see that CC uses a single-wire protocol. When the DP function is turned on, the SBU line becomes the AUX_P/AUX_N differential line in the DP protocol (its polarity can be modified according to the forward and reverse insertion directions), and is responsible for transmitting key information such as DPCD and EDID of the device

USBType-C socket side view

USB-Type-C plug outlet side view

Technical features

The 5 main features of Type-C make USB Type-C a flexible and scalable interface.

1. Power supply

The default 5V power supply of the USB Type-C interface is backwards compatible with the previous USB interface. Not only that, the new USB Type-C interface contains 4 pins dedicated to power supply and grounding. The "USB Power Delivery Specification" enables the USB Type-C interface to support a voltage of up to 20V and a current of 5A.

2. Symmetrical connection

The USB Type-C interface is symmetrical, so its insertion and extraction and the direction of the cable can be reversed. The liberation of the plugging and unplugging direction solves the main trouble caused by the previous interface. In the past, the type of interface indicated the function of the attached device (Type-A interface for the host, Type-B interface for the external device). The USB Type-C interface can be connected to either end, and the function is defined by the hardware being connected. The interfaces at both ends of the USB Type-C cable are the same, so plugging and unplugging the cable is simplified.

3. Bandwidth

USB Type-C supports USB 2.0, USB3.1 Genl (SuperSpeed ​​USB 5Gbps) and USB 3.1Gen2 (SuperSpeed ​​USB10Gbps) data transfer rates. USB 2.0 and USB 3.1 are each defined by separate specifications. SuperSpeed ​​USB differential signal pairs are distributed on both sides of the interface, so when plugged into the interface in either direction, a set of SuperSpeed ​​USB signal transmission connections is used.

4. Channel Configuration

The USB Type-C interface contains 2 channel configuration (Channel Configuration) signal pins (CC1&CC2) for function negotiation. The above signals determine the interface insertion direction and are used to negotiate the power supply function, alternative mode and peripheral mode on the interface.

5. Non-USB signal transmission

The USB Type-C interface supports a variety of OEM product customization modes to expand device functions. Signal redistribution is achieved through negotiation on the CC channel. The interface can enter two modes, peripheral mode and alternative mode. To enter peripheral mode, a simple logic test is done on the CC channel to determine which peripheral mode is required. To enter alternative mode, Biphase Mark Code (BMC) is used on the CC channel for bidirectional communication to properly set up the link. During this negotiation process, devices at both ends need to agree on the redistribution of signals before making any changes. All USB Type-C interfaces are required to be used as USB-compatible interfaces in non-replacement mode or non-peripheral mode.

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