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10.1 Overview
The H8/532 has an on-chip 16-bit free-running timer (FRT) module with three independent
channels (FRT1, FRT2, and FRT3). All three channels are functionally identical.
Each channel has a 16-bit free-running counter that it uses as a time base. Applications of the
FRT module include rectangular-wave output (up to two independent waveforms per channel),
input pulse width measurement, and measurement of external clock periods.
10.1.1 Features
The features of the free-running timer module are listed below.
• Selection of four clock sources
The free-running counters can be driven by an internal clock source (ø/4, ø/8, or ø/32), or an
external clock input (enabling use as an external event counter).
• Two independent comparators
Each free-running timer channel can generate two independent waveforms.
• Input capture function
The current count can be captured on the rising or falling edge (selectable) of an input signal.
• Four types of interrupts
Compare-match A and B, input capture, and overflow interrupts can be requested
independently.
The compare-match and input capture interrupts can be served by the data transfer controller
(DTC), enabling interrupt-driven data transfer with minimal CPU programming.
• Counter can be cleared under program control
The free-running counters can be cleared on compare-match A.
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Section 10 16-Bit Free-Running Timers
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