Operation In Tio Measure Free-Run/ Clear Input Modes - Renesas M32R/ECU Series User Manual

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10.4.9 Operation in TIO Measure Free-Run/ Clear Input Modes

(1) Outline of TIO measure free-run/ clear input modes
In measure free-run/ clear input modes, the timer is used to measure a duration of time from when the
counter starts counting till when an external capture signal is entered. An interrupt request can be generated
by a counter underflow or execution of a measure operation.
After the timer is enabled (by writing to the enable bit in software), the counter starts counting down synchro-
nously with the count clock. When a capture signal is entered from an external device, the counter value at
that point in time is written into a register called the "measure register."
In measure clear input mode, the counter value is initialized to H'FFFF upon capture, from which the counter
starts counting down again. When the counter underflows, it starts counting down from H'FFFF.
In measure free-run input mode, the counter continues counting down even after capture and upon under-
flow, recycles to H'FFFF, from which it starts counting down again.
To stop the counter, disable count by writing to the enable bit in software.
Count clock
Enable bit
H'FFFF
Undefined
value
Counter
H'0000
Measure register
TIN interrupt request
TIO interrupt request
Figure 10.4.6 Typical Operation in Measure Free-Run Input Mode
Enabled
(by writing to
the enable bit)
Undefined
TIN interrupt request due to
Note: • This diagram does not show detailed timing information.
10-114
MULTIJUNCTION TIMERS
10.4 TIO (Input/Output-Related 16-Bit Timer)
Measure event
(capture) occurs
H'7000
H'7000
TIN interrupt request due to
external event input
TIO interrupt request due
to underflow
32180 Group User's Manual (Rev.1.0)
Measure event
(capture)
H'9000
H'9000
external event input