HD6432138SW datasheet(359/1061 Pages) RENESAS

359 / 1061 page

Section 12 8-Bit Timers

Rev. 4.00 Jun 06, 2006 page 305 of 1004

REJ09B0301-0400

Section 12 8-Bit Timers

12.1

Overview

The H8S/2138 Group and H8S/2134 Group include an 8-bit timer module with two channels

(TMR0 and TMR1). Each channel has an 8-bit counter (TCNT) and two time constant registers

(TCORA and TCORB) that are constantly compared with the TCNT value to detect compare-

matches. The 8-bit timer module can be used as a multifunction timer in a variety of applications,

such as generation of a rectangular-wave output with an arbitrary duty cycle.

The H8S/2138 Group also has two similar 8-bit timer channels (TMRX and TMRY). These

channels can be used in a connected configuration using the timer connection function. TMRX

and TMRY have greater input/output and interrupt function related restrictions than TMR0 and

TMR1.

TMRX has a built-in H8S/2138, but does not have a built-in H8S/2134.

12.1.1

Features

• Selection of clock sources

 TMR0, TMR1: The counter input clock can be selected from six internal clocks and an

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

 TMRX, TMRY: The counter input clock can be selected from three internal clocks and an

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

• Selection of three ways to clear the counters

 The counters can be cleared on compare-match A or B, or by an external reset signal.

• Timer output controlled by two compare-match signals

 The timer output signal in each channel is controlled by two independent compare-match

signals, enabling the timer to be used for various applications, such as the generation of

pulse output or PWM output with an arbitrary duty cycle.

(Note: TMRY does not have a timer output pin.)

• Cascading of the two channels (TMR0, TMR1)

 Operation as a 16-bit timer can be performed using channel 0 as the upper half and channel

1 as the lower half (16-bit count mode).

 Channel 1 can be used to count channel 0 compare-match occurrences (compare-match

count mode).

HD6432138SW Datasheet(PDF) 359 Page - Renesas Technology Corp