Figure 19-10. Pad behaviour
USBE=1
& DETACH=0
& suspend
Idle mode
USBE=0
| DETACH=1
| suspend
Active mode
The SUSPI flag indicated that a suspend state has been detected on the USB bus. This flag
automatically put the USB pad in Idle. The detection of a non-idle event sets the WAKEUPI flag
and wakes-up the USB pad.
Suspend detected = USB pad power down
Clear Suspend by software
SUSPI
WAKEUPI
Clear Resume by software
Resume = USB pad wake-up
PAD status
Power Down
Active
Active
Moreover, the pad can also be put in the “idle” mode if the DETACH bit is set. It come back in
the active mode when the DETACH bit is cleared.
19.8 D+/D- Read/write
The level of D+ and D- can be read and written using the UPOE register. The USB controller has
to be enabled to write a value. For read operation, the USB controller can be enabled or
disabled.
192
AT90USB82/162
7707D–AVR–07/08
ATMEL [ ATMEL ]
