AT89C5131A-RDTUM datasheet(135/188 Pages) ATMEL

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135

4337K–USB–04/08

AT89C5130A/31A-M

When the USB controller receives the SET_FEATURE request: DEVICE_REMOTE_WAKEUP,

the firmware will set to 1 the RMWUPE bit in the USBCON register to enable this functionality.

RMWUPE value will 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 5 ms. When the upstream resume is completed, the UPRSM bit is reset to 0 by

hardware. The firmware will then clear the SDRMWUP bit.

Figure 21-12. Example of REMOTE WAKEUP Management

21.9

Detach Simulation

In order to be re-enumerated by the Host, the AT89C5130A/31A-M has the possibility to simu-

late a DETACH - ATTACH of the USB bus.

The VREF output voltage is between 3.0V and 3.6V. This output can be connected to the D+ pull-

up as shown in Figure 21-13. This output can be put in high-impedance when the DETACH bit is

set to 1 in the USBCON register. Maintaining this output in high impedance for more than 3 µs

will simulate the disconnection of the device. When resetting the DETACH bit, an attach is then

simulated.

USB Controller Init

Detection of a SUSPEND State

SPINT

Set RMWUPE

Suspend Management

Enable Clocks

Upstream RESUME Sent

UPRSM

Clear SPINT

Set SDMWUP

Clear SDRMWUP

SET_FEATURE: DEVICE_REMOTE_WAKEUP

Need USB Resume

UPRSM = 1

AT89C5131A-RDTUM Datasheet(PDF) 135 Page - ATMEL Corporation