Toshiba TLCS-900/H1 Series Manual page 278

3.10.9 Power Management
USB controller (UDC) can be switched from optional resume condition (turn on the power
supply condition) to suspend (Suspension) condition, and it can be returned from suspend
condition to turn on the power supply condition.
This function can be set to low electricity consumption by operating CLK supplying for
UDC.
(1) Switch to suspend condition
The USB host can set the USB device to suspend condition by maintaining IDLE
state. The UDC switches to suspend condition by the following process.
• UDC switches to suspend condition if it detects IDLE state of more than 3 ms
(about 3.07ms) on USB signal. At this point, UDC sets SUSPEND bit of STATUS
register to "1".
• UDC renews USBINTFR1<INT_SUS> and <INT_CLKSTOP> from "0" to "1" if it
detects IDLE state of more than 5 ms (about 5.46ms) on USB signal. Afterward
reset USBCR1<USBCLKE> to "0" to stop USB clock.
• In this condition, all register values in the UDC are kept. However, external access
is not possible except for reading of STATUS register, Current_Config register, and
USBINTFR1, USBINTFR2, USBINTMR1, USBINTMR2 and USBCR1.
(2) Return from suspend condition by host resume
When activity of bus on USB signal is restored by resume condition output from USB
host, the UDC releases SUSPEND condition, and it resets SUSPEND bit of STATUS
register to "0".The system is thereby resumed. The resume condition output from the
host is maintained for at least 20 ms. Therefore effective protocol occurs on USB signal
line after this time has elapsed.
(3) Return from suspend condition by remote wakeup
Remote wakeup is system for prompt resume from suspended USB device to USB
host. Some applications do not support remote wakeup. Remote wakeup is also limited
using from USB host by bus enumeration.
UDC remote wakeup function can be used when it is permitted.
Setting remote wakeup by bus can be confirmed by bit7 of Current_Config register.
When this bit is "1", remote wakeup can be used. Remote wakeup is not disabled by
this bit. Therefore, if this bit shows disabled, remote wakeup must not be set. If it fills
the conditions, output resumes condition output to USB host by writing
USBCR1<WAKEUP> from "1" to "0" of UDC in suspend condition. And it prompts
resume from UDC to host. After UDC changes to suspend condition, WAKEUP input is
ignored
USBINTFR1<INT_SUS> is set to "1".
for 2 ms. Therefore,
92CH21-276
remote wakeup becomes
TMP92CH21
effective when
2009-06-19