UM10413
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User manual
Rev. 1 — 16 December 2011
39 of 268
NXP Semiconductors
UM10413
MPT612 User manual
For example, if a system wakes up from power-down using a LOW level on external
interrupt 0 pin, its post-wake-up code must reset bit EINT0 to allow future entry into the
power-down mode. If bit EINT0 is left set to logic 1, subsequent attempt(s) to invoke
power-down mode fail. This also applies to external interrupt handling.
More details on power-down mode are discussed in the following chapters.
10.5.3 Interrupt wake-up register (INTWAKE - 0xE01F C144)
Enable bits in register INTWAKE allow the external interrupts and other sources to wake
up the processor if it is in Power-down mode. Map the related EINTn function to the pin in
order for the wake-up process to take place. It is not necessary for the interrupt to be
enabled in the Vectored Interrupt Controller for a wake-up to take place. This arrangement
allows capabilities, such as an external interrupt input wake-up the processor from
Power-down mode without causing an interrupt (simply resuming operation), or allowing
an interrupt to be enabled during Power-down without waking the processor if it is
asserted (eliminating the need to disable the interrupt if the wake-up feature is not
desirable in the application).
If an external interrupt pin is required to be a source for waking the MPT612 from
Power-down mode, the corresponding bit in register External Interrupt Flag must be
cleared; see
Table 38.
External interrupt flag register (EXTINT - address 0xE01F C140) bit description
Bit
Symbol
Description
Reset
value
0
EINT0
in level-sensitive mode, this bit is set if EINT0 function is selected for its pin, and pin is in its
active state. In edge-sensitive mode, this bit is set if EINT0 function is selected for its pin, and
the selected edge occurs on the pin.
cleared by writing a logic 1 to it, except in level-sensitive mode when pin is in its active state (for
example, if EINT0 is selected to be LOW, level-sensitive and a LOW level is present on the
corresponding pin, this bit cannot be cleared; it can only be cleared when signal on pin is HIGH).
0
1
EINT1
in level-sensitive mode, this bit is set if EINT1 function is selected for its pin, and pin is in its
active state. In edge-sensitive mode, this bit is set if EINT1 function is selected for its pin, and
the selected edge occurs on the pin.
cleared by writing a logic 1 to it, except in level-sensitive mode when pin is in its active state (for
example, if EINT1 is selected to be LOW, level-sensitive and a LOW level is present on the
corresponding pin, this bit cannot be cleared; it can only be cleared when signal on pin is HIGH).
0
2
EINT2
in level-sensitive mode, this bit is set if EINT2 function is selected for its pin, and the pin is in its
active state. In edge-sensitive mode, this bit is set if EINT2 function is selected for its pin, and
the selected edge occurs on the pin.
cleared by writing a logic 1 to it, except in level-sensitive mode when pin is in its active state (for
example, if EINT2 is selected to be LOW, level-sensitive and a LOW level is present on the
corresponding pin, this bit cannot be cleared; it can be cleared only when the signal on the pin is
HIGH).
0
7:3
-
reserved; user software must not write logic 1s to reserved bits; value read from a reserved bit is
not defined
n/a