Rev. 3.0, 10/02, page 490 of 686
(2) Resume Operation from Up-Stream
If the USB bus enters a non-suspend state from the suspend state by resume signal output from
up-stream, perform the operation shown in figure 15.9.
USB cable connected
USB bus in suspend state
A resume interrupts in
requested from the
up-stream.
A suspend/resume
interrupt occurs.
USB function
Firmware
No
Yes
Start USB clock oscillation
Check if SPRSs of UIFR3 is
set to 0
Clear CK48READY of
UIFR3 to 0
Clear SPRSi of UIFR3 to 0
Clear SOF of UIFR3 to 0
Return to normal state
SOF marker operation
Set SFME of UCTLR to 1
Yes
Yes
Yes
No
No
No
Detect SOF packet.
Wait for an interrupt occurrence
Receive SOF
Detect SOF packed
An interrupt occurs.
Start SOF marker function
Is SOF
marker function
used?
Check operating state
USB clock stabilization
time has passed?
A USB operating clock
oscillation detection
interrupt occurs
Software
standby?
USB module
stopped?
Cancel USB module stop mode
Clear MSTPB0 of MSTPCRB to 0
Wait for USB operating clock
stabilization
Figure 15.9 Resume Operation from Up-Stream
Summary of Contents for H8S/2215 Series
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