MEC1404 Datasheet, PDF (338/572 Pages) Microchip Technology – Keyboard and Embedded Controller Products for Notebook PC

MEC140X/1X
Offset ^{See Table 22-2, "Register Summary"}
Bits
Description
Type
Default
Reset
Event
1:0 PU/PD (PU_PD)
These bits are used to enable an internal pull-up or pull-down resis-
tor device on the pin.
00 = None. Pin tristates when no active driver is present on the pin.
01 = Pull Up Enabled
10 = Pull Down Enabled (Note 22-7)
11 = Repeater mode. Pin is kept at previous voltage level when no
active driver is present on the pin.
R/W
Note 22-6 nSYSRS
T
Note 22-6 See Section 22.5.4, "Pin Control Registers," on page 326 for the offset and default values for each
GPIO Pin Control Register.
Note 22-7
The internal pull-down control should not be selected when configured for an LPC function, which
uses the PCI_PIO buffer. Signals with PCI_PIO buffer type do not have an internal pull-down. This
configuration option has no effect on the pin.
TABLE 22-3: EDGE ENABLE AND INTERRUPT DETECTION BITS DEFINITION
Edge
Enable
D7
0
0
0
0
0
0
0
0
1
1
1
Interrupt Detection Bits
D6
D5
D4
0
0
0
0
0
1
0
1
0
0
1
1
1
0
0
1
0
1
1
1
0
1
1
1
1
0
1
1
1
0
1
1
1
Selected Function
Low Level Sensitive
High Level Sensitive
Reserved
Reserved
Interrupt events are disabled
Reserved
Reserved
Reserved
Rising Edge Triggered
Falling Edge Triggered
Either edge triggered
Note:
Only edge triggered interrupts can wake up the main ring oscillator. The GPIO must be enabled for edge-
triggered interrupts and the GPIO interrupt must be enabled in the interrupt aggregator in order to wake up
the ring when the ring is shut down.
APPLICATION NOTE: All GPIO interrupt detection configurations default to '0000', which is low level interrupt.
Having interrupt detection enabled will un-gated the clock to the GPIO module whenever the
interrupt is active, which increases power consumption. Interrupt detection should be
disabled when not required to save power; this is especially true for pin interfaces (i.e., LPC).
DS00001956D-page 338
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