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15.5.2
USB Cable Connection/Disconnection
(1) USB Cable Connection (when USB module stop or software standby is not used)
If the USB cable enters the connection state from the disconnection state in an application (self
powered) where USB module stop or software standby mode is not used, perform the operation
shown in figure 15.4. In bus-powered mode, perform the operation described in note 2.
USB function
Connect the USB cable
A VBUS interrupt occurs
from 15.5.1
After completing the bus-
powered function initialization
Automatical load
EPINFO to UDC core
Complete the USB module
initialization
Receive bus reset from the host
A bus reset interrupt occurs.
Notes:
*
1 A VBUS interrupt in the USB module cannot be detected in the software standby state or
in the USB module stop state.
*2
During the password function, power is applied after the USB cable has been connected.
Accordingly, immediately after completing the power-on reset, initialization (15.5.1), clearing all FIFO,
and system preparation, enable the D+ pull-up via a general port and cancel the UDC core reset state.
Figure 15.4 USB Cable Connection (When USB Module Stop or Software Standby is not
Firmware
1
*
2
*
Used)
Clear VBUSi of UIFR3
Check if VBUSs of UIFR3
is set
Clear all FIFOS
System ready?
Yes
Enable D+ pull up by the
port
Cancel UDC core reset
(Clear UDCRST of UCTLR to 0)
Initialize the firmware
Wait for a setup interrupt
Rev. 3.0, 10/02, page 485 of 686
Check the USB cable
connection state
No
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