```USB 备忘单```

```USB 备忘单```
USB Cheat Sheet (2022)

原始链接: https://fabiensanglard.net/usbcheat/index.html

## USB 快速参考本快速参考整理了USB版本及其规格，旨在理清经常令人困惑的术语。USB已经发展显著，营销名称如“SuperSpeed”掩盖了潜在的技术差异。 **主要规格：** USB 1.1 提供 12 Mbps (1.5 MiB/s)，USB 2.0 提升至 480 Mbps (60 MiB/s)。USB 3.0/3.1/3.2 (SuperSpeed) 的范围从 5Gbps (625 MiB/s) 到 20Gbps (2500 MiB/s)，具体取决于代数和通道数。USB4 进一步将速度提高到 20Gbps 或 40Gbps (5000 MiB/s)。 **理解代数：** “Gen XxY” 表示代数和使用的通道数（例如，3.2 Gen 2x2 使用 2 个通道，每个通道 10Gbps，总共 20Gbps）。更多通道需要电缆中更多的线（4、8 或 12 根）。 **连接器和电源：** USB-A/B 使用 4 或 8 根线，而 USB-C 使用 12 根线，从而实现更高的带宽。电源传输差异很大，从 2.5W (USB 2.0) 到 240W (USB-C PD 3.1 EPR)。USB-C 还包括用于替代模式（如 DisplayPort）的引脚。

一个黑客新闻的讨论围绕着最近分享的“USB 备忘单”（fabiensanglard.net）。用户们争论 USB 标准令人困惑的命名规则——特别是 USB 3.0、3.1 和 3.2 都代表不同的速度（5-20gbps）的问题。一些人认为“Gen X.Y”命名（例如 3.2 Gen 2）是合乎逻辑的，类似于 PCIe，而另一些人指出 USB 历史上的修订和重新定义使其对消费者而言始终不明确。关于改进备忘单的建议包括添加 Type-C 连接器引脚、信号方案（如 PAM3）、Power Delivery (PD) 世代以及专有充电标准（如 Quickcharge）的细节。对话还涉及 Thunderbolt (TB5)，明确它现在与 USB4v2 共享相同的 80gbps 标准和 PCIe 直通能力，并通过 USB-C 连接工作。

USB Cheat Sheet

May 05, 2022

USB Cheat Sheet

I spend time investigating a non-existing bug today because I misunderstood a USB term. So I made myself a cheat sheet. Maybe it will save time to someone.

Marketing Name	Also Known As	Signal Gbps	Signal MiB/s	Wires	Cable
USB 1.1	Full Speed	12 Mbps	1.5 MiB/s	4	4m
USB 2.0	Hi-Speed	480 Mbps	60 MiB/s	4	4m
SuperSpeed USB 5Gbps	USB 3.0 USB 3.1 USB 3.2 USB 3.1 Gen 1 USB 3.2 Gen 1	5000 Mbps	625 MiB/s	8	3m
SuperSpeedPlus USB 10Gbps	USB 3.1 USB 3.2 USB 3.1 Gen 2 USB 3.2 Gen 2	10000 Mbps	1250 MiB/s	8	2m
SuperSpeedPlus USB 20Gbps	USB 3.2 USB 3.2 Gen 2x2	20000 Mbps	2500 MiB/s	12	1m
USB4 20Gbps	USB4 Gen 2×2 USB4	20000 Mbps	2500 MiB/s	12	0.8m
USB4 40Gbps	USB4 Gen 3×2 USB4	40000 Mbps	5000 MiB/s	12	0.8m

Gen naming Convention, lanes, and Speed

USB Gen A x B
A = Generation
B = Num lanes used

Name	Signal	Sig Total^a	Encoding	Effective b^b	Effective B^b	Real Life^c
USB 3.2 Gen 1x1	5,000 Mbps	5,000 Mbps	8b/10b	4,000 Mbps	500 MiB/s	400 MiB/s^[1]
USB 3.2 Gen 1x2	5,000 Mbps	10,000 Mbps	8b/10b	8,000 Mbps	1,000 MiB/s	800 MiB/s
USB 3.2 Gen 2x1	10,000 Mbps	10,000 Mbps	128b/132b	9,696 Mbps	1,212 MiB/s	780 MiB/s^[2]
USB 3.2 Gen 2x2	10,000 Mbps	20,000 Mbps	128b/132b	19,392 Mbps	2,424 MiB/s	1,600 MiB/s^[4]
USB 4 Gen 2x2	10,000 Mbps	20,000 Mbps	128b/132b	19,392 Mbps	2,424 MiB/s	1,600 MiB/s
USB 4 Gen 3x2	20,000 Mbps	40,000 Mbps	128b/132b	38,787 Mbps	4,848 MiB/s	2,700 MiB/s^[5]

Note: Multi-lanes systems, uses lane striping (on TX) and lane bonding (on RX).
^a - What they put on the box.
^b - Rate with encoding overhead. e.g, 8b/10b = 20%.
^c - Real life sequencial read rate.

Cables

4 wires: PWR, GND, D+, D-.
8 wires: PWR, GND, D+, D-. RX+ , RX- , TX- , TX+.
12 wires: PWR, GND, D+, D-, RX1+, RX1-, RX2-, RX2+, TX1+, TX1-, TX2-, TX2+.

Note: 1 USB lane = 1 twisted wire pair +/-.
Note: 4 wires = 1 half-duplex lane, 8 wires = 2 lanes (one up, one down), and 12 wires = 4 lanes (two up, two down).

USB-A/B: Connectors 4/8 wires

USB-C: Connectors 12 wires

Only the USB Type-C connector has enough pins to support two lanes.

- CC1 and CC2 are downstream facing port (DFP) and upstream facing port (UFP) detection. Also used for power negotiation and alt mode switch.
- SBU1 and SBU2 are secondary bus wires, for the DisplayPort AUX channel and hot plug detection (HPD).

Charge rates / Cable types

Specifications	Max. Voltage	Max. Current	Max. Power
USB 2.0	5V	500mA	2.5W
USB 3.0 / USB3.1	5V	900mA	4.5W
USB Battery Charging (BC) 1.2	5V	1.5A	7.5W
USB-C Current Mode (non-PD)	5V	3A	15W
USB-C / Power Delivery (PD 1/2)	20V	5A	100W
USB-C PD 3.1 (EPR)	48V	5A	240W

Specifications

USB 1.0 (Jan, 1996).
USB 1.1 (Sep, 1998).
USB 2.0 (Apr, 2000).
USB 3.0 (Nov, 2008).
USB 3.1 (Jul, 2013).
USB 3.2 (Sep, 2017).
USB 4.0 (Aug, 2019).

References

*

```USB 备忘单``` USB Cheat Sheet (2022)

```USB 备忘单```
USB Cheat Sheet (2022)