AT89C5131-RDTIL datasheet(130/176 Pages) ATMEL

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130

AT89C5131

4136B–USB–09/03

Upstream Resume

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

Wake Up purpose.

Whe n

t he

U SB

co ntr o ll er

r e ceive s

th e

SET _F EAT URE

r equ est:

DEVICE_REMOTE_WAKEUP, the firmware will set to 1 the RMWUPE bit in the USB-

CON 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

clearing first the SPINT bit in the USBINT register and by setting then to 1 the SDRM-

WUP 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 com-

pleted, the UPRSM bit is reset to 0 by hardware. The firmware will then clear the

SDRMWUP bit.

Figure 64. Example of REMOTE WAKEUP Management

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

AT89C5131-RDTIL Datasheet(PDF) 130 Page - ATMEL Corporation