Freescale Semiconductor MC68HC08KH12 - Manual (Page 122)

Advance Information MC68HC(7)08KH12 — Rev. 1.1
122 Freescale Semiconductor
bit can be set to 1 by the host request only. It can be cleared either by
hardware when a fault condition was detected or by software through
the host request. Reset clears this bit.
1 = Downstream port is enabled
0 = Downstream port is disabled
LOWSP1-LOWSP4 — Full Speed / Low Speed Port Control Bit
This read/write bit specifies the attached device in the downstream
port is low speed device or full speed device. Software is responsible
to detect the device attachment and whether a device is full or low
speed. Reset clears this bit.
1 = Downstream port is low speed
0 = Downstream port is full speed
NOTE: after a port is enabled, HUB will automatically generate a low speed
keep awake signal to the port every millisecond.
RST1-RST4 — Force Reset to the Downstream Port
This read/write bit forces a reset signal (SE0 state) onto the USB
downstream port data lines. This bit can be set by the host request
SetPortFeature (PORT_RESET) only. Software should control the
timing of the forced reset signaling downstream for at least 10 ms.
Reset clears this bit.
1 = Force downstream port data lines to SE0 state
0 = Default
RESUM1-RESUM4 — Force Resume to the Downstream Port
This read/write bit forces a resume signal (“K” state) onto the USB
downstream port data lines. This bit is set to reflect the resume signal
when the software detects the remote resume signal on the data lines
of the selective suspend downstream port. Downstream selective
resume sequence to a port may also be initiated via the host request
ClearPortFeature (PORT_SUSPEND). Software should control the
timing of the forced resume signaling downstream for at least 20 ms.
To indicate the end of the resume, a low speed EOP signal will be
followed when this control bit changes from 1 to 0. Reset clears this
bit.
1 = Force downstream port data lines to “K” state
0 = Default