MC68HC705P9 Datasheet, PDF (103/160 Pages) Motorola, Inc – HCMOS Microcontroller Unit

Freescale Semiconductor, Inc.
Timer
Operation
9.4.1 Pin Functions
The timer uses two pins.
9.4.1.1 PD7/TCAP
PD7/TCAP is the input capture pin. When an active edge occurs on
PD7/TCAP, the timer transfers the current counter value to the input
capture registers. PD7/TCAP is also an I/O port pin.
9.4.1.2 TCMP
TCMP is the output-only output compare pin. When the counter value
matches the value written in the output compare registers, the timer
transfers the output level bit, OLVL, to the TCMP pin.
9.4.2 Input Capture
The input capture function is a means to record the time at which an
external event occurs. When the input capture circuitry detects an active
edge on the PD7/TCAP pin, it latches the contents of the timer registers
into the input capture registers. The polarity of the active edge is
programmable.
Latching values into the input capture registers at successive edges of
the same polarity measures the period of the input signal on the
PD7/TCAP pin. Latching the counter values at successive edges of
opposite polarity measures the pulse width of the signal. Figure 9-3
shows the logic of the input capture function.
MC68HC705P9 — Rev. 4.0
MOTOROLA
Timer
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Technical Data
103