Renesas H8/38024 Series, Hardware Manual

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Rev. 6.00, 08/04, page 301 of 628
9.7 Asynchronous Event Counter (AEC)
9.7.1 Overview
The asynchronous event counter is incremented by external event clock or internal clock input.
Features
Features of the asynchronous event counter are given below.
•
Can count asynchronous events
Can count external events input asynchronously without regard to the operation of base clocks
φ
and
φ
SUB
.
The counter has a 16-bit configuration, enabling it to count up to 65536 (2
16
) events.
•
Can also be used as two independent 8-bit event counter channels.
•
Can be used as single-channel independent 16-bit event counter.
•
Event/clock input is enabled only when IRQAEC is high or event counter PWM output
(IECPWM) is high.
•
Both edge sensing can be used for IRQAEC or event counter PWM output (IECPWM)
interrupts. When the asynchronous counter is not used, independent interrupt function use is
possible.
•
When an event counter PWM is used, event clock input enabling/disabling can be performed
automatically in a fixed cycle.
•
External event input or a prescaler output clock can be selected by software for the ECH and
ECL clock sources.
φ
/2,
φ
/4, or
φ
/8 can be selected as the prescaler output clock.
•
Both edge counting is possible for AEVL and AEVH.
•
Counter resetting and halting of the count-up function controllable by software
•
Automatic interrupt generation on detection of event counter overflow
•
Use of module standby mode enables this module to be placed in standby mode independently
when not used.