Section 11 16-Bit Free-Running Timer (FRT)
This LSI has an on-chip 16-bit free-running timer (FRT). The FRT operates on the basis of the 16-
bit free-running counter (FRC), and outputs two independent waveforms, and measures the input
pulse width and external clock periods.
11.1
Features
• Selection of four clock sources
One of the three internal clocks (φ/2, φ/8, or φ/32), or an external clock input can be
selected (enabling use as an external event counter).
• Two independent comparators
Two independent waveforms can be output.
• Four independent input capture channels
The rising or falling edge can be selected.
Buffer modes can be specified.
• Counter clearing
The free-running counters can be cleared on compare-match A.
• Seven independent interrupts
Two compare-match interrupts, four input capture interrupts, and one overflow interrupt
can be requested independently.
• Special functions provided by automatic addition function
The contents of OCRAR and OCRAF can be added to the contents of OCRA
automatically, enabling a periodic waveform to be generated without software intervention.
The contents of ICRD can be added automatically to the contents of OCRDM × 2, enabling
input capture operations in this interval to be restricted.
Figure 11.1 shows a block diagram of the FRT.
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Section 11 16-Bit Free-Running Timer (FRT)
Rev. 3.00 Jul. 14, 2005 Page 277 of 986
REJ09B0098-0300