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 CC2The Sink supplies pull-down resistors (Rd) on CC1 and CC2After 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;