mc68hc916y3 Freescale Semiconductor, Inc, mc68hc916y3 Datasheet - Page 99

• Manufacturer Part Number: mc68hc916y3
• Description: Mc68hc16y3 16 Bit Microcontroller
• Manufacturer: Freescale Semiconductor, Inc

4.13 Exceptions
4.13.1 Exception Vectors
MC68HC16Y3/916Y3
USER’S MANUAL
Total execution time is calculated using the expression:
Where:
(CL
(CL
(CL
(CL
Refer to the CPU16 Reference Manual (CPU16RM/AD) for more information on this
topic.
An exception is an event that preempts normal instruction processing. Exception
processing makes the transition from normal instruction execution to execution of a
routine that deals with the exception.
Each exception has an assigned vector that points to an associated handler routine.
Exception processing includes all operations required to transfer control to a handler
routine, but does not include execution of the handler routine itself. Keep the distinc-
tion between exception processing and execution of an exception handler in mind
while reading this section.
An exception vector is the address of a routine that handles an exception. Exception
vectors are contained in a data structure called the exception vector table, which is
located in the first 512 bytes of bank 0. Refer to Table 4-5 for the exception vector
table.
All vectors except the reset vector consist of one word and reside in data space. The
reset vector consists of four words that reside in program space. Refer to SECTION 5
SINGLE-CHIP INTEGRATION MODULE 2 for information concerning address space
types and the function code outputs. There are 52 predefined or reserved vectors, and
200 user-defined vectors.
Each vector is assigned an 8-bit number. Vector numbers for some exceptions are
generated by external devices; others are supplied by the processor. There is a direct
mapping of vector number to vector table address. The processor left shifts the vector
number one place (multiplies by two) to convert it to an address.
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) = Clock periods used for internal operation
) = Total clock periods per instruction
) = Clock periods used for program access
) = Clock periods used for operand access
Freescale Semiconductor, Inc.
For More Information On This Product,
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Go to: www.freescale.com
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MOTOROLA
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