Atmel Xplained Evaluation Board AT32UC3A3-XPLD AT32UC3A3-XPLD Data Sheet

32072H–AVR32–10/2012

FIFO size (i.e. the DPRAM size), so the value of CFGOK does not consider memory 
allocation conflicts.

 shows the pad behavior.

Figure 27-8. Pad Behavior

• In the Idle state, the pad is put in low power consumption mode, i.e., the differential receiver 

of the USB pad is off, and internal pull-down with strong value(15K) are set in both DP/DM to 
avoid floating lines.

• In the Active state, the pad is working.

 illustrates the pad events leading to a PAD state change.

Figure 27-9. Pad Events

The SUSP bit is set and the Wake-Up Interrupt (WAKEUP) bit in UDINT is cleared when a USB
“Suspend” state has been detected on the USB bus. This event automatically puts the USB pad
in the Idle state. The detection of a non-idle event sets WAKEUP, clears SUSP and wakes up
the USB pad.

Idle

Active

   USBE = 1
& DETACH = 0
& Suspend

  USBE = 0
| DETACH = 1
| Suspend

SUSP

Suspend detected

Cleared on wake-up

Wake-up detected

Cleared by software to acknowledge the interrupt

WAKEUP

PAD State

Active

Idle

Active