USB Type-C spec

1、定義

本規(guī)范定義了 USB Type-C 的 receptacles、plug、cables，即插座、插頭、電纜。

USB Type-C 是一種 USB 接口外形標準，擁有比 Type-A 及 Type-B 均小的體積，支持正反插。

USB Type-C 有更多的 PIN 腳，傳統(tǒng)的 USB Type-A 只有五個 PIN 腳。

USB Type-C?要注意的是，插座和插頭的 CC pin、D+/D- 數(shù)量不一樣，另外，插頭的 B5 是 Vconn

CC：Configuration Channel

拆分后的 PIN 腳功能圖如下

typec 主要的新增 PIN 腳

2、CC PIN

Type-C 增加了 CC1/CC2 和 SBU1/SBU2，CC1/CC2 在 USB Type-C 的各種模式 Normal，PD，ALT，Accessory 中都發(fā)揮相當重要的作用；而 SBU，主要是為 USB 4.0 設(shè)計，并且在 ALT、Accessory 模式也有其作用。

CC 主要有以下功能：

檢測 USB 端口的連接，例如 a Source to a Sink識別電纜方向在兩個連接的端口之間建立數(shù)據(jù)角色發(fā)現(xiàn)和配置 VBUS，USB Type-C Current modes or USB Power Delivery配置 Vconn發(fā)現(xiàn)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 根據(jù)數(shù)據(jù)傳輸的方向定義了 HOST/Device/OTG 三種角色，其中 OTG 即可作為 HOST，也可作為 Device。在 Type-C 中，也有類似的定義，只是名字有了些許修改。如下所示：

（1）DFP（Downstream Facing Port）

下行端口，可以理解為 Host 或者是 HUB。DFP 提供 VBUS、VCONN，可以接收數(shù)據(jù)。

（2）UFP（Upstream Facing Port）

上行端口，可以理解為 Device。UFP 從 VBUS 中取電，并可提供數(shù)據(jù)。典型設(shè)備是 U 盤，移動硬盤。

（3）DRD（Dual Role Data）

雙角色端口，DRD 既可以做 DFP 也可以做 UFP，也可以在 DFP 與 UFP 間動態(tài)切換。

Type-C 的 Power Role

根據(jù) USB PORT 的供電（受電）情況，USB Type-C 將 port 劃分為 Source、Sink 、DRP(Dual-Role-Power)

4、硬件原理圖

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

功能圖詳細說明

Source

initially the Source has VBUS disabled.

1. 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.

1. The Source uses the

CC

1. pin pull-down characteristic to detect and establish the correct

routing

1. for the USB SuperSpeed data path and determine which CC pin is intended for supplying

VCONN

1. .Once a Sink is detected, the Source enables

VBUS

1. and

VCONN

1. .The Source can

dynamically

1. adjust the value of

Rp

1. 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

1. . 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

1. 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;