DSPIC30F3013AT-20IPT View Datasheet(PDF) - Microchip Technology
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DSPIC30F3013AT-20IPT Datasheet PDF : 220 Pages
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Each hard trap that occurs must be acknowledged
before code execution of any type may continue. If a
lower priority hard trap occurs while a higher priority
trap is pending, acknowledged, or is being processed,
a hard trap conflict occurs.
The device is automatically Reset in a hard trap conflict
condition. The TRAPR Status bit (RCON<15>) is set
when the Reset occurs so that the condition may be
detected in software.
FIGURE 8-1:
TRAP VECTORS
IVT
AIVT
Reset - GOTO Instruction
Reset - GOTO Address
Reserved
Oscillator Fail Trap Vector
Address Error Trap Vector
Stack Error Trap Vector
Math Error Trap Vector
Reserved Vector
Reserved Vector
Reserved Vector
Interrupt 0 Vector
Interrupt 1 Vector
—
—
—
Interrupt 52 Vector
Interrupt 53 Vector
Reserved
Reserved
Reserved
Oscillator Fail Trap Vector
Stack Error Trap Vector
Address Error Trap Vector
Math Error Trap Vector
Reserved Vector
Reserved Vector
Reserved Vector
Interrupt 0 Vector
Interrupt 1 Vector
—
—
—
Interrupt 52 Vector
Interrupt 53 Vector
0x000000
0x000002
0x000004
0x000014
0x00007E
0x000080
0x000082
0x000084
0x000094
0x0000FE
8.4 Interrupt Sequence
All interrupt event flags are sampled in the beginning of
each instruction cycle by the IFSx registers. A pending
Interrupt Request (IRQ) is indicated by the flag bit
being equal to a ‘1’ in an IFSx register. The IRQ causes
an interrupt to occur if the corresponding bit in the Inter-
rupt Enable (IECx) register is set. For the remainder of
the instruction cycle, the priorities of all pending inter-
rupt requests are evaluated.
If there is a pending IRQ with a priority level greater
than the current processor priority level in the IPL bits,
the processor is interrupted.
The processor then stacks the current program counter
and the low byte of the processor STATUS register
(SRL), as shown in Figure 8-2. The low byte of the
STATUS register contains the processor priority level at
the time prior to the beginning of the interrupt cycle.
The processor then loads the priority level for this inter-
dsPIC30F3014/4013
rupt into the STATUS register. This action disables all
lower priority interrupts until the completion of the
Interrupt Service Routine.
FIGURE 8-2:
0x0000 15
INTERRUPT STACK FRAME
0
PC<15:0>
SRL IPL3 PC<22:16>
<Free Word>
W15 (before CALL)
W15 (after CALL)
POP : [--W15]
PUSH: [W15++]
Note 1: The user can always lower the priority
level by writing a new value into SR. The
Interrupt Service Routine must clear the
interrupt flag bits in the IFSx register
before lowering the processor interrupt
priority, in order to avoid recursive
interrupts.
2: The IPL3 bit (CORCON<3>) is always
clear when interrupts are being pro-
cessed. It is set only during execution of
traps.
The RETFIE (return from interrupt) instruction unstacks
the program counter and STATUS registers to return
the processor to its state prior to the interrupt
sequence.
8.5 Alternate Vector Table
In program memory, the Interrupt Vector Table (IVT) is
followed by the Alternate Interrupt Vector Table (AIVT),
as shown in Figure 8-1. Access to the alternate vector
table is provided by the ALTIVT bit in the INTCON2 reg-
ister. If the ALTIVT bit is set, all interrupt and exception
processes use the alternate vectors instead of the
default vectors. The alternate vectors are organized in
the same manner as the default vectors. The AIVT sup-
ports emulation and debugging efforts by providing a
means to switch between an application and a support
environment without requiring the interrupt vectors to
be reprogrammed. This feature also enables switching
between applications for evaluation of different
software algorithms at run time.
If the AIVT is not required, the program memory
allocated to the AIVT may be used for other purposes.
AIVT is not a protected section and may be freely
programmed by the user.
© 2007 Microchip Technology Inc.
DS70138E-page 59
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