AT83SND2CMP3B datasheet(118/241 Pages) ATMEL

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118

4341F–MP3–03/06

AT8xC51SND2C/MP3B

The USB controller is then re-activated.

Figure 16-13.

Example of a Suspend/Resume Management

16.10.3

Upstream Resume

A USB device can be allowed by the Host to send an upstream resume for Remote Wake-up

purpose.

When the USB controller receives the SET_FEATURE request: DEVICE_REMOTE_WAKEUP,

the firmware should set to 1 the RMWUPE bit in the USBCON register to enable this functional-

ity. RMWUPE value should be 0 in the other cases.

If the device is in SUSPEND mode, the USB controller can send an upstream resume by clear-

ing first the SPINT bit in the USBINT register and by setting then to 1 the SDRMWUP bit in the

USBCON register. The USB controller sets to 1 the UPRSM bit in the USBCON register. All

clocks must be enabled first. The Remote Wake is sent only if the USB bus was in Suspend

state for at least 5ms. When the upstream resume is completed, the UPRSM bit is reset to 0 by

hardware. The firmware should then clear the SDRMWUP bit.

USB Controller Init

Detection of a SUSPEND State

SPINT

Set SUSPCLK

Disable PLL

microcontroller in Power-down

Detection of a RESUME State

WUPCPU

Enable PLL

Clear SUSPCLK

Clear WUPCPU Bit

Clear SPINT

AT83SND2CMP3B Datasheet(PDF) 118 Page - ATMEL Corporation