Datasheet

Table Of Contents
Section 15 Universal Serial Bus Interface (USB)
REJ09B0140-0900 Rev. 9.00 Page 549 of 846
Sep 16, 2010
H8S/2215 Group
(2) USB Cable Connection (When USB Module Stop or Software Standby Is Used)
If the USB cable enters the connection state from disconnection state an application (self powered)
where USB module stop or software standby mode is used, perform the operation as shown in
figure 15.5.
Connect the USB cable
USB function
Firmware
No
Ye s
Receive bus reset
A bus reset interrupt occurs
Start USB operating
clock oscillation
USB
operating clock stabilization
time has passed?
Cancel USB module stop mode
Clear MSTPB0 in MSTPCRB to 0
Check by using
the port function in IRQx = 1
Clear CK48READY in UIFR3
to 0
Enable D+ pull-up by
the port
Initializa the firmware
Wait for a setup interrupt
Ye s
Ye s
Ye s
No
No
No
Cancel UDC core reset
Clear UDCRST in UCTLR to 0
Clear all FIFOs
Wait for USB operating clock
stabilization
Complete USB
module initialization
A USB operating clock
stabilization detection
interrupt occurs
System ready?
Software
standby?
USB module
stopped?
Automatically load
EPINFO to the UDC core
*
*
*
EXIRQx
EXIRQx
External interrupt IRQx
Note:
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.
Check the USB cable
connection state
Figure 15.5 USB Cable Connection (When USB Module Stop or Software Standby Is Used)