USB Type-C spec

Jasonangel

发布于 2023-08-22 14:08:15

2770

发布于 2023-08-22 14:08:15

文章被收录于专栏：嵌入式Linux系统开发嵌入式Linux系统开发

1、定义

本规范定义了 USB Type-C 的 receptacles、plug、cables，即插座、插头、电缆。

USB Type-C 是一种 USB 接口外形标准，拥有比 Type-A 及 Type-B 均小的体积，支持正反插。

USB Type-C 有更多的 PIN 脚，传统的 USB Type-A 只有五个 PIN 脚。

USB Type-C 要注意的是，插座和插头的 CC pin、D+/D- 数量不一样，另外，插头的 B5 是 Vconn

CC：Configuration Channel

拆分后的 PIN 脚功能图如下

typec 主要的新增 PIN 脚

2、CC PIN

Type-C 增加了 CC1/CC2 和 SBU1/SBU2，CC1/CC2 在 USB Type-C 的各种模式 Normal，PD，ALT，Accessory 中都发挥相当重要的作用；而 SBU，主要是为 USB 4.0 设计，并且在 ALT、Accessory 模式也有其作用。

CC 主要有以下功能：

检测 USB 端口的连接，例如 a Source to a Sink
识别电缆方向
在两个连接的端口之间建立数据角色
发现和配置 VBUS，USB Type-C Current modes or USB Power Delivery
配置 Vconn
发现和配置其他 Alternate and Accessory modes

3、 Data Role、Power Role

Type-C 的 Data Role

在 USB2.0 端口，USB 根据数据传输的方向定义了 HOST/Device/OTG 三种角色，其中 OTG 即可作为 HOST，也可作为 Device。在 Type-C 中，也有类似的定义，只是名字有了些许修改。如下所示：

（1）DFP（Downstream Facing Port）

下行端口，可以理解为 Host 或者是 HUB。DFP 提供 VBUS、VCONN，可以接收数据。

（2）UFP（Upstream Facing Port）

上行端口，可以理解为 Device。UFP 从 VBUS 中取电，并可提供数据。典型设备是 U 盘，移动硬盘。

（3）DRD（Dual Role Data）

双角色端口，DRD 既可以做 DFP 也可以做 UFP，也可以在 DFP 与 UFP 间动态切换。

Type-C 的 Power Role

根据 USB PORT 的供电（受电）情况，USB Type-C 将 port 划分为 Source、Sink 、DRP(Dual-Role-Power)

姓名	年龄
Sink	Port asserting Rd on CC and when attached is consuming power from VBUs
Source	Port asserting Rp on CC and when attached is providing power over VBus
DRP(Dual-Role-Power)	A USB port that can operate as either a Source or a Sink

4、硬件原理图

5、Type-C Data Bus Routing

6、Type-C Attach/Detach Detection

Pull-Up Resistance (Rp)
   Power: Source,Provider
   Data: DFP，Host
   Vconn Source: for eMark IC
Pull-Down Resistance (Rd)
   Power: Sink, Consumer
   Data: UFP,Device

功能图详细说明

Source

initially the Source has VBUS disabled.

The Source supplies pull-up resistors (Rp) on CC1 and CC2 and monitors both to detect a Sink. The presence of an Rd pull-down resistor on either pin indicates that a Sink is being attached. The value of Rp indicates the initial USB Type-C Current level supported by the host.
The Source uses the CC pin pull-down characteristic to detect and establish the correct routing for the USB SuperSpeed data path and determine which CC pin is intended for supplying VCONN.
Once a Sink is detected, the Source enables VBUS and VCONN.
The Source can dynamically adjust the value of Rp to indicate a change in available USB Type-C Current to a Sink.
The Source monitors the continued presence of Rd to detect Sink detach. When a detach event is detected, the Source removes, if supplied, VBUS and VCONN, and returns to step 1.
If the Source supports advanced functions (USB Power Delivery and/or Alternate Modes), USB PD communication is required.

Sink

The Sink terminates both CC1 and CC2 to GND using pull-down resistors.
The Sink determines that a Source is attached by the presence of power on VBUS.
The Sink uses the CC pin pull-up characteristic to detect and establish the correct routing for the USB SuperSpeed data path.
The Sink can optionally monitor CC to detect an available higher USB Type-C Current from the Source. The Sink shall manage its load to stay within the detected Source current limit.
If the Sink supports advanced functions (USB Power Delivery and/or Alternate Modes), USB PD communication is required.

The Source supplies pull-up resistors (Rp) on CC1 and CC2
The Sink supplies pull-down resistors (Rd) on CC1 and CC2
After Source detect Rd on CC (Sink is detected), the Source enables VBUS

7、Timing Parameters

8、State Diagram

1. No TA/Device Connected、Detached or cable only
    HW-DRP toggling
    SW-idle
    
2.TA Connected stage1
    HW-detected Rp/Rd,expose as Sink/Source，alert SW cc-change
    SW-receive cc-change, waiting for tCCDebounce to make sure it's not a noise
    
3.TA Connected stage2
    HW-detected Vbus_valid alert SW ps_change
    SW-after tCCDebounce, check vbus; if valid alert system TA connected and start PD communication;