Motorola M68HC11EVBD, User Manual

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MONITOR PROGRAM
3-6 M68HC11EVBU/D
Table 3-2. Interrupt Vector Jump Table (continued)
Interrupt Vector Field
Timer Input Capture 3 $E0E2 – $E0E4
Timer Input Capture 2 $E0E5 – $E0E7
Timer Input Capture 1 $E0E8 – $E0EA
Real Time Interrupt $E0EB – $E0ED
IRQ $E0EE – $E0F0
XIRQ $E0F1 – $E0F3
Software Interrupt (SWI) $E0F4 – $E0F6
Illegal Opcode $E0F7 – $E0F9
Computer Operating Properly (COP) $E0FA – $E0FC
Clock Monitor $E0FD – $E0FF
To use vectors specified in Table 3-2, you must insert a jump extended opcode in the three byte
field of the vector required. For an example, for the IRQ vector, the following is performed:
1. Place $7E (JMP) at location $00EE.
2. Place IRQ service routine address at locations $00EF and $00F0.
3. The following is an example where the IRQ service routine starts at $0100:
$00EE 7E 01 00 JMP IRQ SERVICE
During initialization BUFFALO checks the first byte of each set of three locations. If a $7E jump
opcode is not found, BUFFALO will install a jump to a routine called STOPIT. This assures
there will be no uninitialized interrupt vectors which would cause undesirable operation during
power up and power down. If an interrupt is accidentally encountered, the STOPIT routine will
force a STOP instruction sequence to be executed. A user may replace any of the JMP STOPIT
instructions with a JMP to a user written interrupt service routine. If a reset is issued via switch
S1, BUFFALO will not overwrite these user jump instructions so they need not be re-initialized
after every reset.