MC68HC705MC4MP datasheet(79/180 Pages) FREESCALE

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General Release Specification

16-Bit Timer

General Release Specification — MC68HC705MC4

Section 9. 16-Bit Timer

9.1 Contents

9.2

Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .79

9.3

Timer. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .80

9.4

Output Compare . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .84

9.5

Input Capture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .87

9.6

Timer Control Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .90

9.7

Timer Status Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .92

9.8

Timer Operation during Wait/Halt Modes . . . . . . . . . . . . . . . . .93

9.2 Introduction

The MC68HC705MC4 MCU contains a single 16-bit programmable

timer with two input capture functions or one input capture function and

an output compare function. The 16-bit timer is driven by the output of a

fixed divide-by-four prescaler operating from the internal clock. The

16-bit timer may be used for many applications including input waveform

measurement while simultaneously generating an output waveform.

Pulse widths can vary from microseconds to seconds depending on the

oscillator frequency selected. The 16-bit timer is also capable of

generating periodic interrupts. See Figure 9-1.

Because the timer has a 16-bit architecture, each function is represented

by two registers. Each register pair contains the high and low byte of that

function. Generally, accessing the low byte of a specific timer function

allows full control of that function; however, an access of the high byte

inhibits that specific timer function until the low byte is also accessed.

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