Datasheet

Table Of Contents

56F8035/56F8025 Data Sheet, Rev. 6

56 Freescale Semiconductor

Part 5 Interrupt Controller (ITCN)

5.1 Introduction

The Interrupt Controller (ITCN) module arbitrates between various interrupt requests (IRQs), to signals

the 56800E core when an interrupt of sufficient priority exists, and to what address to jump in order to

service this interrupt.

5.2 Features

The ITCN module design includes these distinctive features:

• Programmable priority levels for each IRQ

• Two programmable Fast Interrupts

• Notification to SIM module to restart clocks out of Wait and Stop modes

• Ability to drive initial address on the address bus after reset

For further information, see Table 4-2, Interrupt Vector Table Contents.

5.3 Functional Description

The Interrupt Controller is a slave on the IPBus. It contains registers that allow each of the 64 interrupt

sources to be set to one of four priority levels (excluding certain interrupts that are 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, number 0 is the highest priority

and number 63 is the lowest.

5.3.1 Normal Interrupt Handling

Once the INTC 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 Vector Base

Address (VBA) and the vector number to determine the vector address, generating an offset into the vector

table for each interrupt.

5.3.2 Interrupt Nesting

Interrupt exceptions may be nested to allow an IRQ of higher priority than the current exception to be

serviced. The 56800E core controls the masking of interrupt priority levels it will accept by setting the I0

FM_IFROPT_1 $1B Information Option Register 1

$1C Reserved

FM_TSTSIG $1D Test Array Signature Register

Table 4-31 Flash Module Registers Address Map

(FM_BASE = $00 F400) (Continued)