AT90USB646 datasheet(261/456 Pages) ATMEL

261 / 456 page

261

7593L–AVR–09/12

AT90USB64/128

• 2 – BCERRI: B-Connection Error Interrupt flag

Set by hardware when an error occur during the B-Connection (that is, if Peripheral has not con-

nected after 300ms of Vbus delivery request). Shall be cleared by software.

• 1 – VBERRI: V-Bus Error Interrupt flag

Set by hardware when a drop on VBus has been detected. Shall be cleared by software.

• 0 – SRPI: SRP Interrupt flag

Set by hardware when a SRP has been detected. Shall be used in the Host mode only. Shall be

cleared by software.

22.13 USB Software Operating modes

Depending on the USB operating mode, the software should perform some the following

operations:

Power On the USB interface

•Power-On USB pads regulator

• Configure PLL interface

• Enable PLL and wait PLL lock

• Enable USB interface

• Configure USB interface (USB speed, Endpoints configuration...)

• Wait for USB VBUS information connection

• Attach USB device

Power Off the USB interface

• Detach USB interface

• Disable USB interface

• Disable PLL

• Disable USB pad regulator

Suspending the USB interface

• Clear Suspend Bit

• Freeze USB clock

• Disable PLL

• Be sure to have interrupts enable to exit sleep mode

• Make the MCU enter sleep mode

Resuming the USB interface

•Enable PLL

• Wait PLL lock

• Unfreeze USB clock

• Clear Resume information

AT90USB646 Datasheet(PDF) 261 Page - ATMEL Corporation