Table of Contents
Advertisement
M30245 Group
(3) USB Resume Function
Returning Routine from USB Suspend State
To return from the USB suspend state, the M30245 group uses the USB resume interrupt occurred by
receiving the resume signal from the host or the interrupt for remote wakeup for transmitting the
resume signal to the host.
- Returning by Resume Interrupt
When the resume signal is received from the host CPU during the USB suspend state (when de-
tected any bus activity on D+/D- line in suspend detect state), the USB resume interrupt request
www.DataSheet4U.com
occurs, setting "1" to interrupt request bit of USB resume interrupt control register (address 0058
When the USB clock is operated, the USB suspend status flag is automatically set to "0" at this time.
For returning from the suspend state by the USB resume interrupt, follow the procedure below:
1: Return the USB function control unit. (Refer to the next page.)
2: Enable other functions as circumstances demand.
- Returning by Remote Wakeup
When clock operation is started by the remote wakeup interrupt (other than the USB resume inter-
rupt) during the USB suspend state, transmit the resume signal to the host CPU as follows:
1: Return the USB function control unit. (Refer to the next page.)
2: Set USB remote wakeup bit to "1" and transmit the resume signal to the host CPU. (Retain "1" for
min. 1ms to max. 15ms.)
3: Set USB remote wakeup bit to "0" and complete the resume signal transmission. The USB sus-
pend status flag is automatically cleared at this time.
Also, when returning from the stop mode, the main clock dividing ratio has been set to 8-dividing
mode, for which resetting is required. Wait for enough oscillation stabilization time before resetting
main clock division select bit of system clock control register 0 (address 0006
"Clock-Generating Circuit" of Chapter 1 "Hardware".)
Rev.2.00 Oct 16, 2006
REJ09B0340-0200
page 164 of 354
2. USB function
).
16
). (For details, refer to
16
Advertisement
Table of Contents
