MC68HC908LD64 Datasheet, PDF (194/362 Pages) Freescale Semiconductor, Inc – Microcontrollers

Universal Serial Bus Module (USB)
14.6 Hub Function I/O Registers
The USB hub function provides a set of control/status registers and
sixteen data registers that provide storage for the buffering of data
between the USB hub function and the CPU.
14.6.1 USB Hub Root Port Control Register (HRPCR)
Address: $005E
Bit 7
6
5
4
3
2
1
Bit 0
Read: 0
0
0
0
D0+
D0–
RESUM0 SUSPND
Write:
Reset: 0
0
0
0
0
0
X
X
X = Indeterminate
= Unimplemented
Figure 14-3. USB Hub Root Port Control Register (HRPCR)
RESUM0 — Force Resume to the Root Port
This read/write bit forces a resume signal (K state) onto the USB root
port data lines to initiate a remote wakeup. Software should control
the timing of the forced resume to be between 10ms and 15ms.
Reset clears this bit.
1 = Force root port data lines to K state
0 = Default
SUSPND — USB Suspend Control Bit
To save power, this read/write bit should be set by the software if a
constant idle state for more than 3ms is detected on the USB bus.
Setting this bit puts the transceiver into a power savings mode.
This bit also determines the latch scheme for the data lines of the root
port and the downstream port. When this bit is 1, the current state
shown on the data lines will be reflected to the data register (D+/D–)
directly. When the bit is 0, the data registers are the latched state
sampled at the last EOF2 sample point. The hub repeater’s function
is affected by this bit too. The upstream and downstream traffic will be
blocked if this bit is set to 1. When the global resume or the
downstream remote wakeup signal is found by the suspended hub,
Data Sheet
194
Universal Serial Bus Module (USB)
MC68HC908LD64 — Rev. 3.0
Freescale Semiconductor