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TMP92CZ26A
92CZ26A-450
3.16.9 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 suspends
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
USB host can be set USB device to suspend condition by keeping on IDLE state.
UDC switches to suspend condition by below process.
• UDC switches to suspend condition if it detect IDLE state of more than 3 ms on
USB signal. At this point, set SUSPEND bit of STATUS register to “1”.
• After switch to suspend condition, if besides pass away 2 ms, UDC renews
USBINTFR1<INT_SUS> from “0” to “1”. After USBINTFR1<INT_CLKSTOP>
was renewed from “0” to “1”, set USBCR1<USBCLKE> to “0”, and be stopped
supply of CLK (USB_CLK).
In this condition, all register value into the UDC is kept. However, accessing from
external can’t be accessed except reading of STATUS register, Current_Config
register, and USBINTFR1, USBINTFR2, USBINTMR1, USBINTMR2 and
USBCR1
(2) Return from suspend condition by host resume
Way to UDC change from suspend condition to resume condition have two type;
resume condition output from USB host and remote wakeup.
When activity of bus on USB signal restore by resume condition output from USB,
UDC reset SUSPEND output from “1” to “0”, and it resets SUSPEND bit of STATUS
register from “0”. And it resumed system. Resume condition output from this host keep
on no less than during 10 ms. Therefore effective protocol occurring on USB signal line
is after pass away this time.
(3) Return from suspend condition by remote wakeup
Remote wakeup is system for prompt resume from suspending USB device to USB
host. Remote wakeup isn’t supported by condition. And remote wakeup is limited using
from USB host by bus enumeration.
Function of remote wakeup in UDC can be used when it is permitted.
Setting remote wakeup by bus can be confirmed bit7 of Current_Config register.
When this bit is “1”, remote wakeup can be used. Remote wakeup doesn’t disable in
this bit. Therefore, if this bit show disable, must not set remote wakeup. If it fill the
conditions, output resume 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, during 2 ms ignore
WAKEUP input. Therefore, remote wakeup become effective by
USBINTFR1<INT_SUS> was set to “1”.