![Freescale Semiconductor MC9S12ZVM series Reference Manual Download Page 142](http://html1.mh-extra.com/html/freescale-semiconductor/mc9s12zvm-series/mc9s12zvm-series_reference-manual_2330602142.webp)
Chapter 4 Interrupt (S12ZINTV0)
MC9S12ZVM Family Reference Manual Rev. 1.3
142
Freescale Semiconductor
4.5.3
Wake Up from Stop or Wait Mode
4.5.3.1
CPU Wake Up from Stop or Wait Mode
Every I-bit maskable interrupt request which is configured to be handled by the CPU is capable of waking
the MCU from stop or wait mode. Additionally machine exceptions can wake-up the MCU from stop or
wait mode.
To determine whether an I-bit maskable interrupts is qualified to wake up the CPU or not, the same settings
as in normal run mode are applied during stop or wait mode:
•
If the I-bit in the CCW is set, all I-bit maskable interrupts are masked from waking up the MCU.
•
An I-bit maskable interrupt is ignored if it is configured to a priority level below or equal to the
current IPL in CCW.
The X-bit maskable interrupt request can wake up the MCU from stop or wait mode at anytime, even if
the X-bit in CCW is set
1
. If the X-bit maskable interrupt request is used to wake-up the MCU with the X-
bit in the CCW set, the associated ISR is not called. The CPU then resumes program execution with the
instruction following the WAI or STOP instruction. This feature works following the same rules like any
interrupt request, i.e. care must be taken that the X-bit maskable interrupt request used for wake-up
remains active at least until the system begins execution of the instruction following the WAI or STOP
instruction; otherwise, wake-up may not occur.
1. The capability of the XIRQ pin to wake-up the MCU with the X bit set may not be available if, for example, the XIRQ pin is
shared with other peripheral modules on the device. Please refer to the Port Integration Module (PIM) section of the MCU
reference manual for details.