Freescale Semiconductor MC68HC08KH12 Manuel D’Utilisation

Advance Information

MC68HC(7)08KH12

 — 

Rev. 1.1

120

Freescale Semiconductor

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 10 ms and 15 
ms. 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 at 
least 3ms constant idle state is detected on USB bus. Setting this bit 
puts the transceiver and regulator 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 suspend hub, 
software is responsible to propagate the traffic between the root port 
and the enabled downstream port by setting the RESUMx control bit. 
Reset clears this bit.

Address:

$005E

Bit  7

6

5

4

3

2

1

Bit  0

Read:

0

0

0

RESUM0 SUSPND

0

D0+

D0–

Write:

Reset:

0

0

0

0

0

0

X

X

= Unimplemented

X = Indeterminate