MC56F8346 Freescale Semiconductor, Inc, MC56F8346 Datasheet - Page 80

• Manufacturer Part Number: MC56F8346
• Description: 56f8300 16-bit Digital Signal Controllers
• Manufacturer: Freescale Semiconductor, Inc

5.3 Functional Description
The Interrupt Controller is a slave on the IPBus. It contains registers allowing each of the 82 interrupt
sources to be set to one of four priority levels, excluding certain interrupts of fixed priority. Next, all of
the interrupt requests of a given level are priority encoded to determine the lowest numerical value of the
active interrupt requests for that level. Within a given priority level, zero is the highest priority, while
number 81 is the lowest.
5.3.1
Once the ITCN has determined that an interrupt is to be serviced and which interrupt has the highest
priority, an interrupt vector address is generated. Normal interrupt handling concatenates the VBA and the
vector number to determine the vector address. In this way, an offset is generated into the vector table for
each interrupt.
5.3.2
Interrupt exceptions may be nested to allow an IRQ of higher priority than the current exception to be
serviced. The following tables define the nesting requirements for each priority level.
5.3.3
Fast interrupts are described in the DSP56800E Reference Manual. The interrupt controller recognizes
fast interrupts before the core does.
A fast interrupt is defined (to the ITCN) by:
80
1. Core status register bits indicating current interrupt mask within the core.
Normal Interrupt Handling
Interrupt Nesting
Fast Interrupt Handling
SR[9]
1. See IPIC field definition in
0
0
1
1
IPIC_LEVEL[1:0]
1
00
01
10
11
Table 5-1 Interrupt Mask Bit Definition
Table 5-2 Interrupt Priority Encoding
SR[8]
1
0
1
0
1
1
No Interrupt or SWILP
Priority 0
Priority 1
Priorities 2 or 3
56F8346 Technical Data, Rev. 15
Part
Current Interrupt
Priorities 0, 1, 2, 3
Priorities 1, 2, 3
Priorities 2, 3
Priority 3
Priority Level
5.6.30.2.
Permitted Exceptions
Priority 3
Priorities 0, 1, 2, 3
Priorities 1, 2, 3
Priorities 2, 3
Exception Priority
Required Nested
None
Priority 0
Priorities 0, 1
Priorities 0, 1, 2
Masked Exceptions
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