HD64F2149YV datasheet(373/1075 Pages) RENESAS

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Section 12 8-Bit Timers

Rev. 3.00 Jan 18, 2006 page 345 of 1044

REJ09B0280-0300

Section 12 8-Bit Timers

12.1

Overview

The H8S/2169 or H8S/2149 includes 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/2169 or H8S/2149 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.

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).

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