HD404449 Datasheet, PDF (18/123 Pages) Hitachi Semiconductor – HD404449 SERIES

HD404449 Series
An interrupt request occurs when the IF is set to 1 and the IM is set to 0. If the IE is 1 at that point, the
interrupt is processed. A priority programmable logic array (PLA) generates the vector address assigned to
that interrupt source.
The interrupt processing sequence is shown in figure 10 and an interrupt processing flowchart is shown in
figure 11. After an interrupt is acknowledged, the previous instruction is completed in the first cycle. The
IE is reset in the second cycle, the carry, status, and program counter values are pushed onto the stack
during the second and third cycles, and the program jumps to the vector address to execute the instruction
in the third cycle.
Program the JMPL instruction at each vector address, to branch the program to the start address of the
interrupt program, and reset the IF by a software instruction within the interrupt program.
Table 2 Vector Addresses and Interrupt Priorities
Reset/Interrupt
Priority
Vector Address
RESET, STOPC*
—
$0000
INT₀
1
INT₁
2
Timer A
3
$0002
$0004
$0006
Timer B, INT₂
4
Timer C, INT₃
5
Timer D, A/D
6
$0008
$000A
$000C
Serial 1, Serial 2
7
$000E
Note: * The STOPC interrupt request is valid only in stop mode
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