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General-Purpose Interface Integration
The idle mode request, idle acknowledge, and wake-up request (GPIOi_SWAKEUP, where i = 1, 2, 3, 4,
5, and 6) are sideband signals between the PRCM module and the general-purpose interface (see
, Hardware Requests).
25.3.1.1.4.2 Operating Modes
The following four operating modes are defined for the modules:
•
Active mode: The module runs synchronously on the interface clock; interrupts can be generated
based on the configuration and external signals.
•
Idle mode: Power-saving mode with the module in a waiting state. The interface clock can be stopped,
an interrupt cannot be generated, and a wake-up signal can be generated based on the configuration
and external signals.
If the debounce clock provided by the PRCM module is active, the debounce cell can sample and filter
the input to generate a wake-up event. If the debounce clock is inactive, the debounce cell gates all
input signals and thus cannot be used.
•
Inactive mode: The module has no activity. The interface clock can be stopped, an interrupt cannot be
generated, and the wake-up feature is inhibited.
•
Disabled mode: The module is not used. The internal clock paths are gated, and an interrupt or
wake-up request cannot be generated.
Idle and inactive modes are configured within the module and activated on request by the PRCM module
(see
, Power, Reset, and Clock Management) through sideband signals (see
, System Power Management and Wake-Up).
The disabled mode is set by software through a dedicated configuration bit, the GPIOi.
DISABLEMODULE bit (0: The module is enabled and clocks are not gated; 1: The module is disabled and
clocks are gated). It unconditionally gates the internal clock paths that are not used for the L4
interconnect.
25.3.1.1.4.3 System Power Management and Wake-Up
The PRCM module can require GPIOs to be idled for power saving purposes.
The general-purpose interface has six identical idle mode request/acknowledge (handshake) mechanisms
with the PRCM module (see
and
, Hardware Requests): One per GPIO
module. The general-purpose interface allows GPIOs to enter idle mode based on the
GPIOi.
[4:3] IDLEMODE bit field.
The idle acknowledge depends on the configuration and activity of each GPIO module:
•
Smart-idle mode (recommended)
When GPIO is configured in smart-idle mode (GPIOi.
[4:3] IDLEMODE bit field [10])
and receives an idle request from the PRCM module (for GPIO2 to GPIO6: The corresponding bits in
the PRCM.CM_FCLKEN_PER and PRCM.CM_ICLKEN_PER registers cleared to 0 or the
corresponding bit in the PRCM.CM_AUTOIDLE_PER bit set to 1 and L4 interface clock idle transitions;
for GPIO1: the PRCM.CM_FCLKEN_ WKUP[3] EN_GPIO1 bit cleared to 0,
PRCM.CM_ICLKEN_WKUP[3] EN_GPIO1 bit cleared to 0, or the PRCM.CM_AUTOIDLE_WKUP[3]
AUTO_ GPIO1 bit set to 1 and L4 interface clock idle transitions), GPIO checks for more activity
(capture of the input GPIO pins in the GPIOi.
register is complete with no pending
interrupt; all interrupt-status bits are cleared); and there is no access to the
GPIO.
register pending synchronization.
The idle acknowledge is then asserted and the module enters into idle mode. It waits for active system
clock gating by the PRCM module (when all peripherals supplied by the same L4 interface clock
domain are also ready for idle).
When in idle mode (that is, when the PRCM module gates the interface clock), no interrupt occurs and
the module is ready to issue a wake-up request.
When the expected transition occurs on an enabled GPIO input pin, GPIO exits from idle mode, if the
GPIOi.
[2] ENAWAKEUP bit is set to 1 (wake-up capability enabled), and the
corresponding bit in the PRCM.PM_WKEN_PER register is also set to 1 for the GPIO2 to GPIO6,
and/or the PRCM.PM_WKEN_WKUP[3] EN_GPIO1 bit is also set to 1 for GPIO1.
•
Force-idle mode
3471
SWPU177N – December 2009 – Revised November 2010
General-Purpose Interface
Copyright © 2009–2010, Texas Instruments Incorporated
