at89c5131 ATMEL Corporation, at89c5131 Datasheet - Page 132

• Manufacturer Part Number: at89c5131
• Description: 8-bit Flash Microcontroller With Full Speed Usb Device At89c5131
• Manufacturer: ATMEL Corporation

Upstream Resume
Figure 64. Example of REMOTE WAKEUP Management
130
AT89C5131
SET_FEATURE: DEVICE_REMOTE_WAKEUP
Detection of a SUSPEND State
Upstream RESUME Sent
A USB device can be allowed by the Host to send an upstream resume for Remote
Wake Up purpose.
W h e n
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.
UPRSM = 1
t h e
U S B
SPINT
UPRSM
c o n t r o l l e r
Suspend Management
USB Controller Init
Clear SDRMWUP
Set SDMWUP
Set RMWUPE
Enable Clocks
Clear SPINT
r e c e i v e s
t h e
Need USB Resume
S E T _ F E A T U R E
4136C–USB–04/05
r e q u e s t :