
UM10413
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User manual
Rev. 1 — 16 December 2011
38 of 268
NXP Semiconductors
UM10413
MPT612 User manual
10.5 External
interrupt
inputs
The MPT612 includes up to three external interrupt inputs as selectable pin functions.
When the pins are combined, external events can be processed as three independent
interrupt signals. The external interrupt inputs can optionally be used to wake up the
processor from Power-down or Deep power-down mode.
Additionally, all 10 capture inputs can also be used as external interrupts without the
option to wake up the device from Power-down mode.
10.5.1 Register description
The external interrupt function has four registers associated with it. Register EXTINT
contains the interrupt flags and register EXTWAKE contains bits that enable individual
external interrupts to wake up the MPT612 from Power-down mode. Registers EXTMODE
and EXTPOLAR specify the level and edge sensitivity parameters.
[1]
Reset value reflects the data stored in used bits only. It does not include reserved bits content.
10.5.2 External interrupt flag register (EXTINT - 0xE01F C140)
If a pin is selected for its external interrupt function, the level or edge on that pin (selected
by bits in registers EXTPOLAR and EXTMODE) sets its interrupt flag in this register. This
asserts the corresponding interrupt request to the VIC, which causes an interrupt if
interrupts from the pin are enabled.
Writing ones to bits EINT0 through EINT2 in register EXTINT clears the corresponding
bits. In level-sensitive mode, this action is efficacious only when the pin is in its inactive
state.
Once a bit from EINT0 to EINT2 is set and an appropriate code starts to execute (handling
wake-up and/or external interrupt), this bit in register EXTINT must be cleared. Otherwise
the event triggered by activity on pin EINT is not recognized in the future.
Remark:
when a change of external interrupt operating mode (that is, active level/edge) is
performed (including the initialization of an external interrupt), the corresponding bit in
register EXTINT must be cleared. For details, see
.
Table 37.
External interrupt registers
Name
Description
Access Reset
value
Address
EXTINT
external interrupt flag register contains interrupt
flags for EINT0, EINT1, EINT2 and EINT3; see
R/W
0
0xE01F C140
INTWAKE
interrupt wake-up register contains four enable
bits that control whether each external interrupt
causes the processor to wake up from
Power-down mode; see
.
R/W
0
0xE01F C144
EXTMODE
external interrupt mode register controls
whether each pin is edge- or level sensitive.
R/W
0
0xE01F C148
EXTPOLAR
external interrupt polarity register controls
which level or edge on each pin causes an
interrupt.
R/W
0
0xE01F C14C