Datasheet

Section 15 Asynchronous Event Counter (AEC)
Rev. 2.00 Jul. 04, 2007 Page 319 of 692
REJ09B0309-0200
Section 15 Asynchronous Event Counter (AEC)
The asynchronous event counter (AEC) is an event counter that is incremented by external event
clock or internal clock input. Figure 15.1 shows a block diagram of the asynchronous event
counter.
15.1 Features
• Can count asynchronous events
Can count external events input asynchronously without regard to the operation of system
clocks (φ) or subclocks (φ
SUB
).
• Can be used as two-channel independent 8-bit event counter or single-channel independent 16-
bit event counter.
• Event/clock input is enabled when IRQAEC goes high or event counter PWM output
(IECPWM) goes high.
• Falling edge, rising edge, or both edges can be selected as the detected edge for IRQAEC or
event counter PWM output (IECPWM) interrupts. When the asynchronous counter is not used,
they can be used as independent interrupts.
• When an event counter PWM is used, event clock input enabling/disabling can be controlled at
a constant cycle.
• Selection of four clock sources
Three internal clocks (φ/2, φ/4, or φ/8) or external event can be selected.
• Falling edge, rising edge, or both edge counting is possible for the AEVL and AEVH pins.
• Counter resetting and halting of the count-up function can be controlled by software.
• Automatic interrupt generation on detection of an event counter overflow
• Module standby mode enables this module to be placed in standby mode independently when
it is not in use (For details, refer to section 6.4, Module Standby Function).