HD6432138SW datasheet(323/1061 Pages) RENESAS

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Section 11 16-Bit Free-Running Timer

Rev. 4.00 Jun 06, 2006 page 269 of 1004

REJ09B0301-0400

Section 11 16-Bit Free-Running Timer

11.1

Overview

The H8S/2138 Group and H8S/2134 Group have a single-channel on-chip 16-bit free-running

timer (FRT) module that uses a 16-bit free-running counter as a time base. Applications of the

FRT module include rectangular-wave output (up to two independent waveforms), input pulse

width measurement, and measurement of external clock periods.

11.1.1

Features

The features of the free-running timer module are listed below.

• Selection of four clock sources

 The free-running counter can be driven by an internal clock source (φ/2, φ/8, or φ/32), or an

external clock input (enabling use as an external event counter).

• Two independent comparators

 Each comparator can generate an independent waveform.

• Four input capture channels

 The current count can be captured on the rising or falling edge (selectable) of an input

signal.

 The four input capture registers can be used separately, or in a buffer mode.

• Counter can be cleared under program control

 The free-running counters can be cleared on compare-match A.

• Seven independent interrupts

 Two compare-match interrupts, four input capture interrupts, and one overflow interrupt

can be requested independently.

• Special functions provided by automatic addition function

 The contents of OCRAR and OCRAF can be added to the contents of OCRA

automatically, enabling a periodic waveform to be generated without software intervention.

 The contents of ICRD can be added automatically to the contents of OCRDM × 2, enabling

input capture operations in this interval to be restricted.

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