Section 9 8-Bit Timers
9.1
Overview
The H8/3337 Series and H8/3397 Series include an 8-bit timer module with two channels
(numbered 0 and 1). 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-
match events. One of the many applications of the 8-bit timer module is to generate a rectangular-
wave output with an arbitrary duty cycle.
9.1.1
Features
The features of the 8-bit timer module are listed below.
•
Selection of seven clock sources
The counters can be driven by one of six internal clock signals or an external clock input
(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 generate output waveforms with an arbitrary duty cycle, or PWM
waveforms.
•
Three independent interrupts
Compare-match A and B and overflow interrupts can be requested independently.
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