Atmel ARM-Based Evaluation Kit AT91SAM9N12-EK AT91SAM9N12-EK Data Sheet

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SAM9N12/SAM9CN11/SAM9CN12 [DATASHEET]

11063K–ATARM–05-Nov-13

A USB device has several possible states. Refer to Chapter 9 of the Universal Serial Bus Specification, Rev 2.0.

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).

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.

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. 

The wake up feature is not mandatory for all devices and must be negotiated with the host.

Self powered devices can detect 5V VBUS using a PIO as described in the typical connection section. When the device
is not connected to a host, device power consumption can be reduced by disabling MCK for the UDP, disabling UDPCK
and disabling the transceiver. DDP and DDM lines are pulled down by 330 K

Ω resistors. 

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