mc68hc908jb8 Freescale Semiconductor, Inc, mc68hc908jb8 Datasheet - Page 151

• Manufacturer Part Number: mc68hc908jb8
• Description: M68hc08 Microcontrollers
• Manufacturer: Freescale Semiconductor, Inc

9.8.9 USB Control Register 4
MC68HC908JB8•MC68HC08JB8•MC68HC08JT8 — Rev. 2.3
Freescale Semiconductor
NOTE:
Address:
USB control register 4 directly controls the USB data pins D+ and D–. If
the FUSBO bit, and the USBEN bit of the USB address register
(UADDR) are set, the output buffers of the USB modules are enabled
and the corresponding levels of the USB data pins D+ and D– are equal
to the values set by the FDP and the FDM bits.
FUSBO — Force USB Output
FDP — Force D+
FDM — Force D–
Customers must be very careful when setting the UCR4 register. When
the FUSBO and the USBEN bits are set, the USB module is in output
mode and it will not recognize any USB signals including the USB reset
signal. The UCR4 register is used for some special applications.
Customers are not normally expected to use this register.
Reset:
Read:
Write:
This read/write bit enables the USB output buffers.
This read/write bit determinates the output level of D+.
This read/write bit determinates the output level of D–.
1 = Enables USB output buffers
0 = USB module in normal operation
1 = D+ at output high level
0 = D+ at output low level
1 = D– at output high level
0 = D– at output low level
$001B
Bit 7
Universal Serial Bus Module (USB)
0
0
Figure 9-23. USB Control Register 4 (UCR4)
= Unimplemented
6
0
0
5
0
0
4
0
0
Universal Serial Bus Module (USB)
3
0
0
FUSBO
2
0
FDP
1
0
Technical Data
I/O Registers
FDM
Bit 0
0
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