LM3S5D91 Datasheet, PDF (1039/1340 Pages) Texas Instruments – Stellaris® LM3S5D91 Microcontroller

Stellaris^® LM3S5D91 Microcontroller
Bit/Field
2
1:0
Name
EPENDE
EPEN
Type
R/W
R/W
Reset
0
0x0
Description
EPEN Drive Enable
This bit specifies whether the USB0EPEN signal is driven or undriven
(tristate). When driven, the signal value is specified by the EPEN field.
When not driven, the EPEN field is ignored and the USB0EPEN signal is
placed in a high-impedance state.
Value Description
0 Not Driven
The USB0EPEN signal is high impedance.
1 Driven
The USB0EPEN signal is driven to the logical value specified by
the value of the EPEN field.
The USB0EPEN signal is undriven at reset because the sense of the
external power supply enable is unknown. By adding the high-impedance
state, system designers may bias the power supply enable to the
disabled state using a large resistor (100 kΩ) and later configure and
drive the output signal to enable the power supply.
External Power Supply Enable Configuration
This bit field specifies and controls the logical value driven on the
USB0EPEN signal.
Value Description
0x0 Power Enable Active Low
The USB0EPEN signal is driven Low if the EPENDE bit is set.
0x1 Power Enable Active High
The USB0EPEN signal is driven High if the EPENDE bit is set.
0x2 Power Enable High if VBUS Low
The USB0EPEN signal is driven High when the A device is not
recognized.
0x3 Power Enable High if VBUS High
The USB0EPEN signal is driven High when the A device is
recognized.
January 22, 2012
Texas Instruments-Production Data
1039