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9.4.2 USB HUB Downstream Port Control Register (HDP1CR-HDP4CR)
MC68HC(7)08KH12
Rev. 1.1
—
Freescale Semiconductor
EOF2 is generated by KH12 every millisecond, if SOF is not detected
when three or more EOF2 has occurred, software can set the
SUSPND-bit and put KH12 into suspend mode.
D0+/D0– — Root Port Differential Data
These read only bits are the differential data shown on the HUB root
ports. When the bit SUSPND is 0, the data is the latched state at the
last EOF2 sample point. When the bit SUSPND is 1, the data reflects
the current state on the data line while accessing this register.
Address: $0051
Bit 7
6
Read:
PEN1
LOWSP1
Write:
Reset:
0
0
↓
Address: $0054
Read:
PEN4
LOWSP4
Write:
Reset:
0
0
= Unimplemented
Figure 9-3. USB HUB Downstream Port Control Registers
PEN1-PEN4 — Downstream Port Enable Control Bit
This read/write bit determines whether the enabled or disabled state
should be assigned to the downstream port. Setting this bit 1 to
enable the port and clear the bit to disable the port. In the enabled
state a full-speed port propagates all downstream signaling, a low-
speed port propagates downstream low-speed packet traffic when
preceded by the preamble PID. An enabled port propagates all
upstream signaling including full speed and low speed packets. This
5
4
3
RST1
RESUM1
SUSP1
0
0
0
RST4
RESUM4
SUSP4
0
0
0
X = Indeterminate
(HDP1CR-HDP4CR)
2
1
Bit 0
0
D1+
D1–
0
X
X
↓
0
D4+
D4–
0
X
X
Advance Information
121
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