S3C80A5B
INTERRUPT STRUCTURE
5-3
S3C80A5B INTERRUPT STRUCTURE
The S3P80A5B microcontroller supports two kinds interrupt structure
— Vectored
Interrupt
— Non vectored interrupt (Reset interrupt): INTR
The S3C80A5B microcontroller supports thirteen interrupt sources. Nine of the interrupt sources have a
corresponding interrupt vector address; the remaining four interrupt sources share the same vector address. Five
interrupt levels are recognized by the CPU in this device-specific interrupt structure, as shown in Figure 5-2.
When multiple interrupt levels are active, the interrupt priority register (IPR) determines the order in which
contending interrupts are to be serviced. If multiple interrupts occur within the same interrupt level, the interrupt
with the lowest vector address is usually processed first. (The relative priorities of multiple interrupts within a
single level are fixed in hardware.)
When the CPU grants an interrupt request, interrupt processing starts: All other interrupts are disabled and the
program counter value and state flags are pushed to stack. The starting address of the service routine is fetched
from the appropriate vector address (plus the next 8-bit value to concatenate the full 16-bit address) and the
service routine is executed. The S3C80A5B microcontroller supports non vectored interrupt - Interrupt with
Reset(INTR) - to occur interrupt with system reset. The Interrupt with Reset(INTR) has nothing to do with interrupt
levels, vectors and the registers that are related to interrupt setting.
It occurs only according to the “P0” during
“ STOP ” regardless any other things.
Namely, only when a falling/rising edge occurs at any pin of Port 0 during
STOP status, this INTR and a system reset occurs even though SYM.0 is “0”(Disable interrupt). But it dose not
occurs while the oscillation - “IDLE” or “OPERATING” status- even though a falling/rising edge occurs at port 0.
Following is the sequence that occurs Interrupt with Reset(INTR).
1. The oscillation status is “freeze” : STOP mode
2. A falling/rising edge is detected to any pin of Port 0.
3. INTR occurs and it makes system reset.
4. STOP mode is released by this system reset.
NOTE
Because H/W reset occurs whenever INTR occurs. A user should aware of the each ports, system
register, control register etc.”