High Speed USB

Specification

  • USB High Speed was introduced in 2000 as part of the USB 2.0 specification
  • Maximun theorectical bandwidth is 480 Mbit/s
  • Uses four data lines - Power (5 V), Ground, and two data lines (D+ and D-)
  • Half-Duplex differential signalling on D+ and D-
  • Uses the traditional USB connectors.

Enumeration

High speed Devices begin the enumeration process identical to Full Speed Devices. High Speed Devices announce to the Host they are ready to be enumerated by asserting a 5 V signal on D+ through the use of a 1.5 kΩ pullup resistor. During the 20 ms enumeration RESET signal sent by the Host, the Device executes the High Speed negotiation process. Upon completing this negotiation the Device, Host and Hub port connecting the Device will operate in High Speed mode.

Differences with Full Speed USB

Microframes

High Speed USB was designed to coexist with Full Speed USB. The designers speculated many systems would have a Host which could simultaneously offer support for Full and High Speed Devices. To achieve compatibility 8 high speed "microframes' are completed within 1 ms.

Frame Size and Transfer Types

HIGH SPEED Frame size: 125 μs

Supported
Transfer
Types
Maximum
Size of
Transfer
Transfers
per frame
Maximum
Theoretical
Throughput
Control 64 bytes 1 64 kByte/s
Interrupt 1024 bytes up to 3 24 MByte/s
Bulk 512 bytes up to 13 53 MByte/s
Isochronous 1024 bytes up to 3 24 MByte/s

USB Bus States and Signal Levels

HS USB
Bus States
Bus Levels
Differential "1" D+ high , D- low
Differential "0" D+ low , D- high
Single Ended 0 (SE0) D+ low , D- low
Single Ended 1 (SE1) D+ high, D- high Invalid condition!
Data J state Differential "1"
Data K State Differential "0"
Idle Data J
Resume Data K
Start of Packet (SOP) switches from Idle to Data K
End of Packet (EOP) SE0 for 2 bits, followed by Data J for 1 bit
Disconnect SE0 >= 2 μs
Connect Idle for 2.5 μs
Reset SE0 >= 2 μs

 Learn More

 
Developing USB with Microchip
Learn more >
 
USB Speeds and Specifications
Learn more >
 
USB Power Delivery
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Type-C
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