Atmel Evaluation Kit AT91SAM9G25-EK AT91SAM9G25-EK Data Sheet
Product codes
AT91SAM9G25-EK
561
SAM9G25 [DATASHEET]
11032D–ATARM–10-Mar-2014
32.6.14 Power Modes
32.6.14.1 Controlling Device States
A USB device has several possible states. Refer to Chapter 9 (USB Device Framework) of the Universal Serial Bus
Specification, Rev 2.0.
Specification, Rev 2.0.
Figure 32-20.UDPHS Device State Diagram
Movement from one state to another depends on the USB bus state or on standard requests sent through control
transactions via the default endpoint (endpoint 0).
transactions via the default endpoint (endpoint 0).
After a period of bus inactivity, the USB device enters Suspend Mode. Accepting Suspend/Resume requests from the
USB host is mandatory. Constraints in Suspend Mode are very strict for bus-powered applications; devices may not
consume more than 500 µA on the USB bus.
USB host is mandatory. Constraints in Suspend Mode are very strict for bus-powered applications; devices may not
consume more than 500 µA on the USB bus.
While in Suspend Mode, the host may wake up a device by sending a resume signal (bus activity) or a USB device may
send a wake-up request to the host, e.g., waking up a PC by moving a USB mouse.
send a wake-up request to the host, e.g., waking up a PC by moving a USB mouse.
The wake-up feature is not mandatory for all devices and must be negotiated with the host.
Attached
Suspended
Suspended
Suspended
Suspended
Hub Reset
or
Deconfigured
Hub
Configured
Bus Inactive
Bus Activity
Bus Inactive
Bus Activity
Bus Inactive
Bus Activity
Bus Inactive
Bus Activity
Reset
Reset
Address
Assigned
Device
Deconfigured
Device
Configured
Powered
Default
Address
Configured
Power
Interruption