At the end of 2020, the release of devices with support for the new generation USB4 / Thunderbolt 4 interfaces is expected. These interfaces are similar, but have a number of fundamental differences. Among these differences, the most significant can be distinguished: the specifications for USB4 are publicly available and anyone can study the basic principles of this interface, unlike Thunderbolt 4.
, USB4 (USB 3.2), USB4 .
USB4?
USB4:
: Intel (Thunderbolt 3/4) USB4 USB-C.
- USB-C
: , : , USB4-, 20 /c. 40 /c, , . Intel – Thunderbolt 4.
- 20 /
- 40 /c
: , USB4-, , USB-C, . , :
- Enhanced SuperSpeed USB (USB3) ( );
- DisplayPort (DP);
- PCI Express (PCIe) ( ).
: (host-to-host).
USB4: USB4 USB Type-C USB PowerDelivery (PD). 100 .
Thunderbolt 3: , USB4, , Thunderbolt 3. , .
USB 3.2
USB4, :
: . (Sideband Channel), , USB Type A/B.
- USB Type A/B, miniUSB, microUSB
: USB 3.2 Gen2 x 2 20 /c, , USB-C. – 10 /c.
- – 20 40 /c
: USB 3.2 USB 2.0, , SuperSpeed-. USB BC (Battery Charging) USB PD , . USB4, USB 2.0 USB 3.2, USB PD USB Type-C.
- USB 3.2, USB4
: USB 3.2 - . DP PCIe, . USB-C (USB-C Alt Mode), DisplayPort Alternate Mode, USB-C , USB 3.2.
- USB 3.2
USB4 USB 3.2
USB 3.2. , – Enhanced SuperSpeed USB 2.0, – USB 3.2 USB 2.0. , .
USB4 . USB 2.0 , . USB 3.2 , , . USB4 .
, USB 3.2 PCIe, (Protocol Adapters). , USB 3.2 (Enhanced SuperSpeed Hub). PCIe (PCIe Switch), . DP . , .
(Router) , . TMU (Time Management Unit).
(Router) – , USB4. USB4, USB4. TMU- USB4. (Connection Manager), -. : (Device Router) - (Host Router).
USB4 , USB4-. (RX/TX) (Sideband (SB)) (SBTX/SBRX). USB4- : . 1 (Lane 1) . 0 1 . .
SB- .
, USB 2.0 USB4 .
, USB Type-C USB4 :
- USB4;
- USB 2.0 (D+/D-);
- CC-, USB PD;
- (VBUS/VCONN/GND).
USB4
USB 3.2. : (Physical Layer), (Link Layer) – (Protocol Layer).
USB4 , . (Physical Layer), : (Logical Layer) (Electrical Layer). (Transport Layer). : (Configuration Layer) (Protocol Adapter Layer). . .
USB4.
:
(Electrical Layer) USB4-: , (jitter), .
(Logical Layer) . .
(Transport Layer) , , . (Control Packets) .
(Configuration Layer) . , .
(Protocol Adapter Layer) . .
(Sideband Channel)
USB4 , USB Type-C (SBU1/SBU2).
:
- ;
- USB4-;
- ;
- (Sleep state).
SBTX SBRX. SBTX SBRX , .
. :
- Link Type (LT) – LT-, . , , ;
- Administrative Type (AT) – AT-, ;
- Re-timer Type (RT) – RT-, .
USB4 . , , . AT- RT- .
, Intel 2017 , , USB4 Thunderbolt 3. , USB4 , - . , : (USB4), (USB Type-C), , DisplayPort, PCI Express, USB3, , host-to-host – , ( Thunderbolt 4) , USB4 «» , Thunderbolt 4.