SCH3112I-NE SMSC [SMSC Corporation], SCH3112I-NE Datasheet - Page 164

• Manufacturer Part Number: SCH3112I-NE
• Description: LPC IO with 8042 KBC, Reset Generation, HWM and Multiple Serial Ports
• Manufacturer: SMSC [SMSC Corporation]

Rev 0.2 (09-28-04)
13.3
13.4
SELECTED
FUNCTION
GPIO
Each GPIO port has an 8-bit control register that controls the behavior of the pin. These registers are
defined in
Each GPIO port may be configured as either an input or an output. If the pin is configured as an
output, it can be programmed as open-drain or push-pull. Inputs and outputs can be configured as
non-inverting or inverting. Bit[0] of each GPIO Configuration Register determines the port direction,
bit[1] determines the signal polarity, and bit[7] determines the output driver type select. The GPIO
configuration register Output Type select bit[7] applies to GPIO functions and the nSMI Alternate
functions
The basic GPIO configuration options are summarized in .
The following GPIO have limited functionality as indicated in the notes in
Functionality,” on page
Control Register have read only bits in position 0, 1, and/or 7.
The operation of the GPIO ports is illustrated in
When a GPIO port is programmed as an input, reading it through the GPIO data register latches either
the inverted or non-inverted logic value present at the GPIO pin. Writing to a GPIO port that is
programmed as an input has no effect
When a GPIO port is programmed as an output, the logic value or the inverted logic value that has
been written into the GPIO data register is output to the GPIO pin. Reading from a GPIO port that is
programmed as an output returns the last value written to the data register
GPIO is programmed as an output, the pin is excluded from the PME and SMI logic.
GPIO Control
GPIO Operation
DIRECTION BIT
Chapter 26, "Runtime Register," on page 293
B0
0
0
1
1
Table 13.3 GPIO Configuration Option
139: GP10, GP11, GP12, GP13, GP14, GP42. The corresponding GPIO
POLARITY BIT
DATASHEET
LPC IO with 8042 KBC, Reset Generation, HWM and Multiple Serial Ports
(Table
B1
0
1
0
1
148
13.4)
Figure
Pin is a non-inverted output.
Pin is an inverted output.
Pin is a non-inverted input.
Pin is an inverted input.
13.1.
section of this specification.
DESCRIPTION
(Table
Table 13.1, “GPIO Pin
13.4). When the
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