The USB-Implementers Forum ( USB-IF ) officially announced the specifications of USB4™ on September 3, 2019. The main update is to supplement the existing USB 3.2 and USB 2.0 architectures to build a new generation of USB. The architecture of USB4™ is based on the Thunderbolt™ protocol specification (which was contributed by Intel to the USB Promoter Group). The maximum transfer rate has been increased from 20Gbps (10G x2) of the original USB 3.2 to 40Gbps (20G x2) (Figure 1) , And can send multiple data and images at the same time.
USB4™ Specification Download
The biggest differences between USB4™ and USB 3.2 are as follows:
- The fastest USB4™ speed is increased to Gen3 X2 = 40Gbps
- The USB4™ Tunneling architecture packs USB3 / DisplayPort™ / PCI Express on the same interface for transmission, and the bandwidth allocation of each protocol can be dynamically adjusted
- USB4™ can choose whether it is compatible with Thunderbolt3 system
- USB4™ supports Host to Host (host and host docking transmission signal)
From the above characteristics, it is not difficult to find that the logical structure of USB4™ is very similar to the network structure. A fixed frame and physical layer are used to carry different protocol packets, which can contain data and image packets, and each packet is marked with an address to ensure correct transmission. Therefore, USB4™ gradually gets rid of the functional limitations of traditional USB Host and USB Device, and USB4™ uses a point-to-point signal transmission method. This design reserves great flexibility for future improvements in transmission speed and functions.
USB4™ test product type and tunneling support specifications
*Note: TBT3 Compatibility must support 10.3125G, but 20.625G is optional.
Overview of USB4™ test items
- Need to pass the USB test, and the product needs to use USB-IF approved connectors and chips. Query URL: https://cms.usb.org/integrators-list (you need to log in as a USB-IF member to enter this page).
- Before USB4™ certification , products must pass USB 2, USB 3.2, USB PD, and USB Type-C® compliance tests
Required before USB4™ Product testing
- Two sets of samples for testing
- USB Product Information sheet
- If your product has special instructions to enter the test mode , please provide it at the same time (Embedded host needs to provide)
- Provide a VIF
USB4™ test tool
- USB4™ Transmitter Automated Test Software (GRL-USB4-TX)
- USB4™ receiver automated test software (GRL-USB4-RXA)
USB4™, USB, USB-C®, USB Type-C® and USB-IF are registered trademarks of USB Implementers Forum
This information is provided for reference only. This information is not and should not be regarded as an official communication of the USB Implementers Forum (USB-IF). The official communication of USB-IF can be obtained from its website usb.org or directly from USB-IF.