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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
Prescaler
by 2
EN
PRE[3:0]
DOZE
HALTED
MOTOROLA
Chapter 19. Programmable Interrupt Timer Modules (PIT0–PIT3)
IPBUS
16-bit PCNTR
16-bit PIT Counter
OVW
16-bit PMR
IPBUS
Figure 19-1. PIT Block Diagram
COUNT = 0
PIF
Load
Counter
PIE
RLD
To Interrupt
Controller
19-1
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