AT89C5122 ATMEL [ATMEL Corporation], AT89C5122 Datasheet - Page 112

• Manufacturer Part Number: AT89C5122
• Description: MICROCONTROLLER WITH USB AND SMART CARD READER INTERFACES
• Manufacturer: ATMEL [ATMEL Corporation]

Upstream Resume
112
AT8xC5122/23
Detection of a SUSPEND State
Detection of a RESUME State
Note :
WUPCPU bit must be
Cleared before enabling
the PLL
Figure 59. Example of a Suspend/Resume Management
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 should set to 1 the RMWUPE bit in the
USBCON register to enable this function. 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
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 should then clear the
SDRMWUP bit.
t h e
U S B
c o n t r o l l e r
WUPCPU
SPINT
microcontroller in power-down
Clear WUPCPU bit
r e c e i v e s
USB Controller Init
Clear SUSPCLK
Set SUSPCLK
Disable PLL
Enable PLL
Clear SPINT
t h e
S E T _ F E A T U R E
Put the USB pads
in power down mode
4202D–SCR–06/05
r e q u e s t :