cs5535 National Semiconductor Corporation, cs5535 Datasheet - Page 149

• Manufacturer Part Number: cs5535
• Description: Geode Cs5535 Companion Multi-function South Bridge
• Manufacturer: National Semiconductor Corporation

Revision 0.8
GPIO Subsystem Functional Description
4.15.4 GPIO Basic I/O Configuration
The General Purpose Input and Output (GPIO) Interface is
illustrated in Figure 4-49. The figure represents one of
twenty-eight GPIOs potentially available. Note the GPIOs
[31:29] and [23] are non-existent. Table 2-8 "GPIO
Options" on page 42 provides a complete list of features for
each GPIO and should be consulted when configuring a
system.
Each GPIO has basic configuration options used to set up
the characteristics of the GPIO for either input or output.
Each of the functions in the list below follows the GPIO reg-
ister strategy outlined inSection 4.15.2 "Register Strategy"
on page 148 unless otherwise noted. This strategy allows
individual GPIOs to be modified without accidentally
changing the characteristics of unrelated GPIOs, and with-
out requiring ‘read-modify-write’ cycles. All values are
active high.
• OUT_EN. When high, enables this GPIO for output. A
• IN_EN. Enables this GPIO for input. A pad may be
• OUT_VAL. This will establish the value driven to the pad
Interrupts
PME
[7:0]
[7:0]
pad may be configured for output, input, or both.
configured for input, output, or both.
when it is selected as an Output, unless either
OUT_AUX1 or OUT_AUX2 are selected. The value
driven to the GPIO pad is subject to an optional inver-
sion.
Status
Read
Negative Edge
Event Enable
X,Y,Z,W Interrupt Mapping Registers
X,Y,Z,W PME Mapping Registers
Positive
Enable
Enable
Edge
Figure 4-49. GPIO Configuration
Count
Event
Counter
Event
Input Conditioning Functions
Event Count
Enable
(Continued)
149
Output
(1 of 8)
AUX1
AUX2
Value
• OUT_INVRT_EN. When high, inverts the Output Value.
• IN_INVRT_EN. Inverts the signal applied to the ball, and
• OUT_OD_EN. Configures this GPIO for open-drain
• OUT_AUX1_SEL and OUT_AUX2_SEL. Selects an
• IN_AUX1_SEL. Selects an internal source as an input
• PU_EN. Applies a weak pull-up to the pad. The effect of
• PD_EN. Applies a weak pull-down to the pad. The effect
presents the inverted value to all follow-up circuitry (i.e.,
input conditioning functions).
operation. When the output pad is to be driven low, the
pad is driven low. When the output pad is to be driven
high, the pad is allowed to float and is not driven.
internal auxiliary source for the Output Value. Table 2-8
"GPIO Options" on page 42 identifies all the possible
internal connections for these two auxiliary sources.
instead of the ball. Table 2-8 "GPIO Options" on page 42
lists all the functions that may be connected in this
manner.
this control is independent of all other settings except
PD_EN. If PU_EN is set by software, PD_EN is auto-
matically cleared.
of this control is independent of all other settings except
PU_EN. If PD_EN is set by software, PU_EN is auto-
matically cleared.
Amount
Filter
Digital
Filter
Enable
Open-Drain
Filter
Enable
Output
Enable
Enable
Invert
Input
Output Invert
Enable
Enable
Input
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Pull-Down
Pull-Up
Enable
Enable
Ball