
194
7799D–AVR–11/10
ATmega8U2/16U2/32U2
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.
20.8
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.
20.9
USB Software Operating modes
Depending on the USB operating mode, the software should perform some of the following
operations:
Power On the USB interface
Configure PLL interface
Enable PLL
Check PLL lock
Enable USB interface
Configure USB interface (USB Endpoint 0 configuration)
Attach USB device
Power Off the USB interface
Detach USB device
Disable USB interface
Disable PLL
Suspending the USB interface
Clear Suspend Bit
Set USB suspend clock
Disable PLL
SUSPI
Suspend detected = USB pad power down
Clear Suspend by software
Resume = USB pad wake-up
Clear Resume by software
WAKEUPI
PAD status
Active
Power Down
Active