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3.2.2
Exception Sources and Vector Table
The factors causing exception handling can be classified as in figure 3-3.
For details of exception handling, the vector numbers of each source, and the vector addresses,
see the applicable hardware manual.
Exception source
Reset
Interrupt
External interrupt
Internal interrupt
(interrupt raised by on-chip peripheral module)
Figure 3-3. Classification of Exception Sources
3.2.3
Outline of Exception Handling Operation
A reset has the highest priority of all exception handling. After the
5(6 pin goes to low level
putting the CPU in reset state, the
5(6 pin is then put at high level, and reset exception handling
is started at the point when the reset conditions are met. For details on reset conditions refer to
the applicable hardware manual. When reset exception handling is started, the CPU gets a start
address from the exception handling vector table, and starts executing the exception handling
routine from that address. During execution of this routine and immediately after, all interrupts
including NMI are masked.
When interrupt exception handling is started, the CPU refers to the stack pointer (R7) and pushes
the PC and CCR contents to the stack. The CCR I bit is then set to 1, a start address is acquired
from the exception handling vector table, and the interrupt exception handling routine is
executed from this address. The stack state in this case is as shown in figure 3-4.
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