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Zynq-7000 AP SoC Technical Reference Manual www.xilinx.com 410
UG585 (v1.11) September 27, 2016
Chapter 15: USB Host, Device, and OTG Controller
15.4.1 Controller State
The device mode includes the active physical state of the controller, left side of Figure 15-12, and the
suspend state maintained in software, right side of the figure. Power interruptions, resets and USB
activity all contribute to the sequencing through these states.
It is the responsibility of software to maintain a state variable to differentiate between the default
FS/HS state and the address/configured states. Change of state from default to address and the
configured states is part of the enumeration process described in the device framework section of
the USB 2.0 Specification.
X-Ref Target - Figure 15-12
Figure 15-12: USB Device State Diagram
Active State
Powered
Attach
Default
FS/HS
Address
FS/HS
Configured
FS/HS
Suspend
FS/HS
Set the Run bit:
usb.USBCMD [RS] = 1.
Power
Interruption
When the
host resets
the device
returns to
the default
state.
Reset
Address
Assigned
Device
Configured
Device
Deconfigured
Software Maintained State
Bus Inactive
Bus Activity
Bus Inactive
Bus Activity
Bus Inactive
Bus Activity
Suspend
FS/HS
Suspend
FS/HS
Suspend State
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