Datasheet

Table Of Contents
Section 15 Universal Serial Bus Interface (USB)
REJ09B0140-0900 Rev. 9.00 Page 551 of 846
Sep 16, 2010
H8S/2215 Group
(4) USB Cable Disconnection (When USB Module Stop or Software Standby Is Used)
If the USB cable enters the disconnection state from the connection state in an application (self
powered) where USB module stop or software standby mode is used, perform the operation shown
in figure 15.7.
Disconnect the USB cable
USB function
Firmware
No
Ye s
Enable D+ pull-up
by the port
Enter software standby
(only if necessary)
Wait for USB
cable connection
Ye s
Ye s
Ye s
No
No
No
Stop USB module
Write MSTPB0 in MSTPCRB to 1
Reset UDC core
Write UDCRST in UCTRL to 1
Reset UDC core
System needs
to enter power-down
mode?
*
1
*
1
*
2
*
2
1.
2.
EXIRQx
External interrupt IRQx
Notes:
A VBUS interrupt in the USB module cannot be detected in the software standby state or in the USB module
stop state. Accordingly, in an application in which software standby or USB module stop is used in self-powered mode,
a VBUS interrupt of the USB must be detected via the external interrupt pin IRQx. In this case, the IRQx pin must be
specified as both edge sensitive. When IRQx is used, a VBUS interrupt in the USB module need not to be used.
Before entering the software standby state, USB module operation must be stopped by setting the MSTPB0 bit in
MSTPCRB register to 1.
Stop SOF marker function
No
Ye s
SOF marker
function enabled?
Stop SOF marker fouction
Clear SFME in UCTLR to 0
Check the USB cable
disconnection state
Start USB operating
clock oscillation
USB
operating clock stabilization
time has passed?
A USB operating clock
stabilization detection
interrupt occurs
Software
standby?
USB module
stopped?
Cancel USB module stop mode
Clear MSTPB0 in MSTPCRB to 0
Wait for USB operating clock
stabilization
Check connections by using
the port function in IRQx = 0
Clear CK48READY in UIFR3
to 0
Figure 15.7 USB Cable Disconnection
(When USB Module Stop or Software Standby Is Used)