Freescale Semiconductor MC68HC08KH12 - Manual (Page 121)

MC68HC(7)08KH12 — Rev. 1.1 Advance Information
Freescale Semiconductor 121
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.
9.4.2 USB HUB Downstream Port Control Register (HDP1CR-HDP4CR)
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
Address: $0051
Bit 7 6 5 4 3 2 1 Bit 0
Read:
PEN1 LOWSP1 RST1 RESUM1 SUSP1
0 D1+ D1–
Write:
Reset: 0 0 0 0 0 0 X X
↓ ↓
Address: $0054
Read:
PEN4 LOWSP4 RST4 RESUM4 SUSP4
0 D4+ D4–
Write:
Reset: 0 0 0 0 0 0 X X
= Unimplemented X = Indeterminate
Figure 9-3. USB HUB Downstream Port Control Registers
(HDP1CR-HDP4CR)