DSPIC30F4012 Microchip Technology Inc., DSPIC30F4012 Datasheet - Page 41

• Manufacturer Part Number: DSPIC30F4012
• Description: Dspic30f4011/4012 Enhanced Flash 16-bit Digital Signal Controller
• Manufacturer: Microchip Technology Inc.

5.0
The dsPIC30F4011/4012 has 30 interrupt sources and
4 processor exceptions (traps), which must be
arbitrated based on a priority scheme.
The CPU is responsible for reading the Interrupt
Vector Table (IVT) and transferring the address con-
tained in the interrupt vector to the program counter.
The interrupt vector is transferred from the program
data bus into the program counter via a 24-bit wide
multiplexer on the input of the program counter.
The Interrupt Vector Table (IVT) and Alternate
Interrupt Vector Table (AIVT) are placed near the
beginning of program memory (0x000004). The IVT
and AIVT are shown in Figure 5-1.
The interrupt controller is responsible for pre-
processing the interrupts and processor exceptions,
prior to their being presented to the processor core.
The peripheral interrupts and traps are enabled,
prioritized and controlled using centralized Special
Function Registers:
• IFS0<15:0>, IFS1<15:0>, IFS2<15:0>
• IEC0<15:0>, IEC1<15:0>, IEC2<15:0>
• IPC0<15:0>... IPC11<7:0>
• IPL<3:0>
• INTCON1<15:0>, INTCON2<15:0>
© 2007 Microchip Technology Inc.
Note: This data sheet summarizes features of this group
of dsPIC30F devices and is not intended to be a complete
reference source. For more information on the CPU,
peripherals, register descriptions and general device
functionality, refer to the “dsPIC30F Family Reference
Manual” (DS70046). For more information on the device
instruction set and programming, refer to the “dsPIC30F/
33F Programmer’s Reference Manual” (DS70157).
All interrupt request flags are maintained in these
three registers. The flags are set by their respec-
tive peripherals or external signals, and they are
cleared via software.
All interrupt enable control bits are maintained in
these three registers. These control bits are used
to individually enable interrupts from the
peripherals or external signals.
The user-assignable priority level associated with
each of these interrupts is held centrally in these
twelve registers.
The current CPU priority level is explicitly stored
in the IPL bits. IPL<3> is present in the CORCON
register, whereas IPL<2:0> are present in the
STATUS register (SR) in the processor core.
Global interrupt control functions are derived from
these two registers. INTCON1 contains the con-
trol and status flags for the processor exceptions.
The INTCON2 register controls the external
interrupt request signal behavior and the use of
the AIVT.
INTERRUPTS
All interrupt sources can be user-assigned to one of
seven priority levels, 1 through 7, via the IPCx
registers. Each interrupt source is associated with an
interrupt vector, as shown in Table 5-1. Levels 7 and 1
represent the highest and lowest maskable priorities,
respectively.
If the NSTDIS bit (INTCON1<15>) is set, nesting of
interrupts is prevented. Thus, if an interrupt is currently
being serviced, processing of a new interrupt is pre-
vented, even if the new interrupt is of higher priority
than the one currently being serviced.
Certain interrupts have specialized control bits for fea-
tures like edge or level triggered interrupts, interrupt-
on-change, etc. Control of these features remains
within the peripheral module which generates the
interrupt.
The DISI instruction can be used to disable the
processing of interrupts of priorities 6 and lower for a
certain number of instructions, during which the DISI bit
(INTCON2<14>) remains set.
When an interrupt is serviced, the PC is loaded with the
address stored in the vector location in program memory
that corresponds to the interrupt. There are 63 different
vectors within the IVT (refer to Figure 5-2). These vec-
tors are contained in locations 0x000004 through
0x0000FE of program memory (refer to Figure 5-2).
These locations contain 24-bit addresses, and in order
to preserve robustness, an address error trap will take
place should the PC attempt to fetch any of these words
during normal execution. This prevents execution of
random data as a result of accidentally decrementing a
PC into vector space, accidentally mapping a data space
address into vector space or the PC rolling over to
0x000000 after reaching the end of implemented
program memory space. Execution of a GOTO instruction
to this vector space will also generate an address error
trap.
Note:
Note:
Note:
dsPIC30F4011/4012
Interrupt flag bits get set when an interrupt
condition occurs, regardless of the state of
its
software should ensure the appropriate
interrupt flag bits are clear prior to
enabling an interrupt.
Assigning a priority level of 0 to an
interrupt source is equivalent to disabling
that interrupt.
The IPL bits become read-only whenever
the NSTDIS bit has been set to ‘1’.
corresponding
enable
DS70135E-page 39
bit.
User