MC68HC908LD64 Datasheet, PDF (195/362 Pages) Freescale Semiconductor, Inc – Microcontrollers

Universal Serial Bus Module (USB)
Hub Function I/O Registers
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.
EOF2 is generated by the MCU every millisecond, if SOF is not
detected when three or more EOF2 have occurred, software can set
the SUSPND bit and put the MCU 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 SUSPND bit is 0, the data is the latched state at the
last EOF2 sample point. When the SUSPND bit is 1, the data reflects
the current state on the data line while accessing this register.
14.6.2 USB Hub Downstream Port Control Registers (HDP1CR–HDP4CR)
Address: $0051–$0054 HRP1CR–HRP4CR
Bit 7
6
5
4
3
2
1
Bit 0
Read:
0
PEN1 LOWSP1 RST1 RESUM1 SUSP1
Write:
D1+
D1–
Read:
0
PEN2 LOWSP2 RST2 RESUM2 SUSP2
Write:
D2+
D2–
Read:
0
PEN3 LOWSP3 RST3 RESUM3 SUSP3
Write:
D3+
D3–
Read:
0
PEN4 LOWSP4 RST4 RESUM4 SUSP4
Write:
D4+
D4–
Reset: 0
0
0
0
0
0
X
X
X = Indeterminate
= Unimplemented
Figure 14-4. USB Hub Downstream Port Control Registers
(HDP1CR–HDP4CR)
PENx — 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 to 1
enables the port; clearing this bit to 0 disables the port. In the enabled
state a full-speed port propagates all downstream signaling;
MC68HC908LD64 — Rev. 3.0
Freescale Semiconductor
Universal Serial Bus Module (USB)
Data Sheet
195