K60P100M100SF2RM Datasheet, PDF (1638/1809 Pages) Freescale Semiconductor, Inc – K60 Sub-Family Reference Manual

Functional description
detection or not, the CD pin is always a reference for card detection. Whether the DAT[3]
pin or the CD pin is used to detect card insertion, the SDHC will send an interrupt (if
enabled) to inform the Host system that a card is inserted.
52.5.8 Power management and wakeup events
When there is no operation between the SDHC and the card through the SD bus, the user
can completely disable the bus clock and SDHC clock in the chip level clock control
module to save power. When the user needs to use the SDHC to communicate with the
card, it can enable the clock and start the operation.
In some circumstances, when the clocks to the SDHC are disabled, for instance, when the
system is in low power mode, there are some events for which the user needs to enable
the clock and handle the event. These events are called wakeup interrupts. The SDHC can
generate these interrupt even when there are no clocks enabled. The three interrupts
which can be used as wake up events are:
1. Card removal interrupt
2. Card insertion interrupt
3. Interrupt from SDIO card
The SDHC offers a power management feature. By clearing the clock enabled bits in the
system control register, the clocks are gated in the low position to the SDHC. For
maximum power saving, the user can disable all the clocks to the SDHC when there is no
operation in progress.
These three wake up events (or wakeup interrupts) can also be used to wake up the
system from low-power modes.
Note
To make the interrupt a wakeup event, when all the clocks to
the SDHC are disabled or when the whole system is in low
power mode, the corresponding wakeup enabled bit needs to be
set. Refer to protocol control register for more information.
52.5.8.1 Setting wakeup events
For the SDHC to respond to a wakeup event, the software must set the respective wakeup
enable bit before the CPU enters sleep mode. Before the software disables the host clock,
it should ensure that all of the following conditions have been met:
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K60 Sub-Family Reference Manual, Rev. 6, Nov 2011
Freescale Semiconductor, Inc.