Section 8 16-Bit Free-Running Timer
8.1
Overview
The H8/3337 Series and H8/3397 Series have an 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.
8.1.1
Features
The features of the free-running timer module are listed below.
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Selection of four clock sources
The free-running counter can be driven by an internal clock source (øP/2, øP/8, or øP/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
Compare-match A and B, input capture A to D, and overflow interrupts are requested
independently.
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