AT90SCR100 datasheet(162/433 Pages) ATMEL

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TPR0327AY–SMS–30Jan09

AT90SCR100

The USB module is able to detect this request and automatically sets the bit USBPI.SUSI. See

“USBPI - USB Protocol Interrupt register” on page 165. This event generates a USB interruption

if the Suspend Interrupt source is not masked and if the USB interrupt is enabled.

Once Suspend mode has been entered, the USB module is able to detect a Resume request.

This event immediately and automatically makes the chip come out the POWER-DOWN mode

and sets (one) bit USBPI.RESI. The fact that bit USBPI.RESI is set (one) triggers a new USB

interrupt if the Resume Interrupt source is not masked and if the USB interrupt is enabled. The

application software shall then clear the interrupt source in its interrupt service routine.

14.6.1

Remote Wake-up

The USB Module is also able to generate a remote wake-up signal (K signal) to raise the com-

munication with the host. To enable this feature, the USBGS.RMWUE bit must be set.

The wake-up signal start to be generated by setting the bit USBCR.URMWU bit.

As soon as this bit is set, a protocol interrupt is generated, if USBPIM.RMWUIM bit is set.

through the raise of USBPI.RMWUI flag.

The remote wake-up signal will be automatically stopped after ~13ms generation. As soon as

the signal stops, the USBGS.RSMON bit is cleared.

Below is a scheme showing all the signal for Remote Wake Up management.

Figure 14-3.

Remote Wake Up State Sequence Description

In order to support the power consumption threshold fixed by the USB specifica-

tions, the oscillator is switched off by hardware. The POWER-DOWN mode must

be entered by setting appropriate configuration in SMCR and followed by a SLEEP

instruction.

When a Resume signal has been detected the USB module does not automati-

cally restarts the internal oscillator. See “Important note about: Entering and

Leaving low consumption modes” on page 47.

Note

When the USBGS.RSMON bit is cleared, do not forget to clear USBCR.URMWU

bit, for next Remote Wake Up sequence.

Note

USBGS.RMWUE

USBCR.URMWU

USBGS.RMSON

USBPI.RMWUI

Enable the feature...

...Start the WakeUp Signal generation...

...and wait the end of the generation.

Flag to be cleared by software

Control to be cleared by software

~13ms

AT90SCR100 Datasheet(PDF) 162 Page - ATMEL Corporation

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