FXTH870xD
Sensors
34
Freescale Semiconductor, Inc.
Figure 19. Interrupt Stack Frame
5.5.2
Vector Summary
Table 20
provides a summary of all interrupt sources. Higher-priority sources are located toward the bottom of the table (at the
higher vector addresses). All of these vectors are a 2-byte address that the firmware uses as the destination address. This allows
the firmware to intercept all vectors and add additional processing as needed. The additional process latency for each interrupt
will be described in
.
Therefore, the high-order byte of the address for the user’s interrupt service routine is located at the lower address in the vector
address column, and the low-order byte of the address for the interrupt service routine is located at the higher address. When an
interrupt condition occurs, an associated flag bit becomes set. If the associated local interrupt enable is set, an interrupt request
is sent to the CPU. Within the CPU, if the global interrupt mask (I bit in the CCR) is 0, the CPU will finish the current instruction,
stack the PCL, PCH, X, A, and CCR CPU registers, set the I bit, and then fetch the interrupt vector for the highest priority pending
interrupt. Processing then continues in the interrupt service routine.
The triggering of any of these vector fetches will wake the MCU from any of the STOP modes.
CONDITION CODE REGISTER
ACCUMULATOR
INDEX REGISTER* (LOW BYTE X)
PROGRAM COUNTER HIGH
PROGRAM COUNTER LOW
UNSTACKING
ORDER
STACKING
ORDER
SP before
the interrupt
SP after
interrupt stacking
Towards HIGHER Addresses
Towards LOWER Addresses
7
0
1
2
3
4
5
5
4
3
2
1
* High byte (H) of index register is not automatically stacked.
Содержание FXTH870 D Series
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