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Rev.2.00
Oct 16, 2006
page 82 of 264
M30245 Group
Universal Serial Bus
REJ03B0005-0200
Power Management Register
The USB Power Management Register, shown in Figure 1.47, is used for power management in the USB FCU.
SUSPEND State Flag:
When the USB FCU does not detect any bus activity on D+/D- (in the J-state) for at least 3ms, it updates the Suspend
State Flag and generates an interrupt. This flag is cleared when active signaling from the host is detected on D+/D- (The
USB FCU generates a resume interrupt), or the CPU sets the Remote Wake-up Bit while in suspend state and it is
subsequently cleared by the CPU. If the USB clock was disabled during the suspend state, the SUSPEND state flag is
not cleared until after the USB clock is re-enabled.
WAKEUP Control Bit:
The CPU writes a "1" to the WAKEUP Control Bit for remote wake-up. While this bit is set and the USB FCU is in suspend
mode, resume signaling is sent to the host. The CPU must keep this bit set for a minimum of 1ms and a maximum of
15ms before writing a "0" to this bit.
Figure 1.47. USB Power Management register (USBPM)
USB Function Interrupt Status Register
USB Function Interrupt Status register, shown in Figure 1.48, is used to indicate the condition that caused a USB
function interrupt to the CPU. A "1" indicates the corresponding condition caused an interrupt.
INTST0, INITST2, INTST4 or INTST6 is set to "1" by the USB FCU when:
The endpoint is enabled from a disabled state;
A data set is successfully sent;
A hardware autoflush takes place or the CPU writes "1" to INxCSR6 (FLUSH) if there are one or two data sets in the
buffer. This causes the EP1-4 IN buffer status flag to change states.
INTST1, INTST3, INTST5 or INTST7 is set to "1" by the USB FCU when:
A data set is successfully received.
INTST8 is an Error Interrupt Status flag, which indicates that an error has been encountered at any endpoint. This flag
is set to "1" by the USB FCU when:
EP0CSR4 (FORCE_STALL) flag is set;
EP0CSR5 (SETUP_END) flag is set;
INxCSR2 (UNDER_RUN) flag is set on any EP1-4 IN endpoint;
OUTxCSR2 (OVER_RUN) flag is set on any EP1-4 OUT endpoint;
OUTxCSR3 (FORCE_STALL) flag is set on any EP1-4OUT endpoint;
Bit Symbol
Bit Name
Function
R W
Must always be "0"
O O
Symbol
USBPM
Address
0282
16
When reset
0000
16
USB Power Management register
b7
(b15)
(b8)
b0
SUSPEND
b7
b0
0 0000 000
Suspend state flag
0 : Not in suspend state
1 : In suspend state
O O
Reserved
0
WAKEUP
Remote wakeup
0 : End remote wakeup signal
1 : Remote wakeup signaling if SUSPEND="1"
O O
00 0 0 0
Note: Read only
Note