sc9s12hy64j0vllr Freescale Semiconductor, Inc, sc9s12hy64j0vllr Datasheet - Page 156

• Manufacturer Part Number: sc9s12hy64j0vllr
• Description: S12 Microcontrollers Mcu 16-bit Hcs12 Cisc 32kb Flash 5v Tray
• Manufacturer: Freescale Semiconductor, Inc

Interrupt Module (S12SINTV1)
4.5
4.5.1
After system reset, software should:
4.5.2
The interrupt request scheme makes it possible to nest I bit maskable interrupt requests handled by the
CPU.
I bit maskable interrupt requests cannot be interrupted by other I bit maskable interrupt requests per
default. In order to make an interrupt service routine (ISR) interruptible, the ISR must explicitly clear the
I bit in the CCR (CLI). After clearing the I bit, other I bit maskable interrupt requests can interrupt the
current ISR.
An ISR of an interruptible I bit maskable interrupt request could basically look like this:
4.5.3
4.5.3.1
Every I bit maskable interrupt request is capable of waking 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 conditions as in
normal run mode are applied during stop or wait mode:
Since there are no clocks running in stop mode, only interrupts which can be asserted asynchronously can
wake-up the MCU from stop mode.
The X bit maskable interrupt request can wake up the MCU from stop or wait mode at anytime, even if the
X bit in CCR is set.
If the X bit maskable interrupt request is used to wake-up the MCU with the X bit in the CCR set, the
associated ISR is not called. The CPU then resumes program execution with the instruction following the
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1. Initialize the interrupt vector base register if the interrupt vector table is not located at the default
2. Enable I bit maskable interrupts by clearing the I bit in the CCR.
3. Enable the X bit maskable interrupt by clearing the X bit in the CCR.
•
1. Service interrupt, e.g., clear interrupt flags, copy data, etc.
2. Clear I bit in the CCR by executing the instruction CLI (thus allowing other I bit maskable interrupt
3. Process data
4. Return from interrupt by executing the instruction RTI
•
location (0xFF80–0xFFF9).
I bit maskable interrupt requests can be interrupted by an interrupt request with a higher priority.
requests)
If the I bit in the CCR is set, all I bit maskable interrupts are masked from waking-up the MCU.
Initialization/Application Information
Initialization
Interrupt Nesting
Wake Up from Stop or Wait Mode
CPU Wake Up from Stop or Wait Mode
MC9S12HY/HA-Family Reference Manual, Rev. 1.04
Freescale Semiconductor