Chapter 19

Programmable Interrupt Timer Modules (PIT0–PIT3)

19.1 Overview

The programmable interrupt timer (PIT) is a 16-bit timer that provides precise interrupts at regular intervals with minimal processor intervention. The timer can either count down from the value written in the modulus register, or it can be a free-running down-counter. This device has four programmable interrupt timers, PIT0–PIT3.

19.2 Block Diagram

System

Clock

Divide by 2

Prescaler

EN

PRE[3:0]

DOZE

HALTED

IPBUS

 

 

 

 

 

 

 

 

 

 

 

 

 

 

16-bit PCNTR

 

 

 

 

 

COUNT = 0

 

 

 

 

 

 

16-bit PIT Counter

 

 

 

 

 

 

Load

Counter

OVW

RLD

16-bit PMR

PIF

PIE

To Interrupt

Controller

IPBUS

Figure 19-1. PIT Block Diagram

MOTOROLA

Chapter 19. Programmable Interrupt Timer Modules (PIT0–PIT3)

19-1

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Motorola MCF5281, MCF5282 user manual Chapter Programmable Interrupt Timer Modules PIT0-PIT3