4.3.4 Internal Interrupts
Eighteen internal interrupts can be requested by the on-chip supporting modules. Each interrupt
source has its own vector number, so the interrupt-handling routine does not have to determine
which interrupt has occurred. All internal interrupts are masked when the I bit in the CCR is set to
“1.” When one of these interrupts is accepted, the I bit is set to 1 to mask further interrupts (except
NMI). The vector numbers are 12 to 35. For the priority order, see table 4-2.
4.3.5 Interrupt Handling
Interrupts are controlled by an interrupt controller that arbitrates between simultaneous interrupt
requests, commands the CPU to start the hardware interrupt exception-handling sequence, and
furnishes the necessary vector number. Figure 4-3 shows a block diagram of the interrupt
controller.
Figure 4-3. Block Diagram of Interrupt Controller
IRQ flag
0
IRQ
0
E
ADF
ADIE
CPU
I (CCR)
NMI interrupt
Interrupt
controller
Priority
decision
IRQ
0
interrupt
Interrupt request
Vector number
ADI
interrupt
*
Note:
*
IRQ edge
0
IRQ
0
E
IRQ flag
0
S Q
IRQ interrupt
0
For edge-sensed
interrupts, these
AND gates change
to the circuit shown below.
67
Summary of Contents for H8/326 Series
Page 67: ...58 ...
Page 121: ...112 ...
Page 274: ... 3 Clock Settling Timing Ø VCC RES STBY tOSC1 tOSC1 Figure 14 8 Clock Setting Timing 265 ...
Page 279: ...270 ...