
80C196KB USER’S GUIDE
cuted. This provides software recovery from random
execution during hardware and software failures. Al-
though available for customer use, these interrupts may
be used in Intel development tools or evaluation boards.
NMI
NMI, the external Non-Maskable Interrupt, is the
highest priority interrupt. It vectors indirectly through
location 203EH. For design symmetry, a mask bit ex-
ists in INTÐMASK1 for the NMI. To prevent acci-
dental masking of an NMI, the bit does not function
and will not stop an NMI from occurring. For future
compatibility, the NMI mask bit must be set to zero.
NMI on the 8096 vectored directly to location 0000H,
so for the 80C196KB to be compatible with 8096 soft-
ware, which uses the NMI, location 203EH must be
loaded with 0000H. The NMI interrupt vector and in-
terrupt vector location is used by some Intel develop-
ment tools. For example, the EV80C196KB evaluation
board uses the NMI to process serial communication
interrupts from the host. The NMI interrupt routine
executes monitor commands passed from the host.
The NMI interrupt is sampled during PH1 or
CLKOUT low and is latched internally. If the pin is
held high, multiple interrupts will not occur.
TRAP
Opcode 0F7H, the TRAP instruction, causes an indi-
rect vector through location 2010H. The TRAP in-
struction provides a single instruction interrupt useful
in designing software debuggers. The TRAP instruc-
tion prevents the acknowledgement of interrupts until
after execution of the next instruction.
Unimplemented Opcode
Opcodes which are not implemented on the 80C196KB
will cause an indirect vector through location 2012H.
User code or hardware which may have failed and run
into an unimplemented opcode can software recover
through this interrupt. The DJNZW instruction is not
supported on the 80C196KB but remains a valid op-
code, therefore, no interrupt will occur.
The programmer must initialize the interrupt vector ta-
ble with the starting addresses of the appropriate inter-
rupt service routines. It is suggested that any unused
interrupts be vectored to an error handling routine. In a
debug environment, it may be desirable to have the rou-
tine lock into a jump to self loop which would be easily
traceable with emulation tools. More sophisticated rou-
tines may be appropriate for production code recover-
ies.
270651 – 10
Figure 5-2. 80C196KB Interrupt Structure
Block Diagram
Five registers control the operation of the interrupt sys-
tem: INTÐPEND, INTÐPEND1, INTÐMASK and
INTÐMASK1 and the PSW which contains a global
disable bit. A block diagram of the system is shown in
Figure 5-2. The transition detector looks for 0 to 1 tran-
sitions on any of the sources. External sources have a
maximum transition speed of one edge every state time.
Sampling will be guaranteed if the level on the interrupt
line is held for at least one state time. If the interrupt
line is not held for at least one state time, the interrupt
may not be detected.
28
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Содержание 80C196KB Series
Страница 1: ...November 1990 80C196KB User s Guide Order Number 270651 003 http www agreenleaf cn...
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Страница 60: ...80C196KB USER S GUIDE Figure 11 8 Actual and Ideal Characteristics 270651 38 56 http www agreenleaf cn...
Страница 61: ...80C196KB USER S GUIDE Figure 11 9 Terminal Based Characteristic 270651 39 57 http www agreenleaf cn...
Страница 70: ...80C196KB USER S GUIDE Figure 13 5 Reset Sequence 80C196KB Reset Sequence 270651 45 66 http www agreenleaf cn...
Страница 83: ...80C196KB USER S GUIDE 270651 80 Figure 15 14 AC Timing Diagrams 79 http www agreenleaf cn...
Страница 84: ...80C196KB USER S GUIDE 270651 81 270651 84 Figure 15 14 AC Timing Diagrams Continued 80 http www agreenleaf cn...