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10.4 TIO (Input/Output-Related 16-Bit Timer)
MULTIJUNCTION TIMERS
10
10-110
32185/32186 Group Hardware Manual
Rev.1.10 REJ09B0235-0110 May 15, 07
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 until when an external capture signal is entered. It is possible to generate an inter-
rupt request upon underflow of the counter or execution of measurement operation and a DMA transfer
request (for only the TIO8 and TIO9) upon underflow of the counter.
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. The counter returns to H’FFFF upon underflow, from which it starts counting down.
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.
Figure 10.4.6 Typical Operation in Measure Free-Run Input Mode
H'FFFF
H'0000
H'7000
H'9000
H'7000
H'9000
DMA transfer request (Note 1)
Count clock
Counter
TIO interrupt request
Enable bit
Measure register
TIN interrupt request
Undefined
value
Undefined
Note 1: Only TIO8 and TIO9 can be generated.
Note: This diagram does not show detailed timing information.
Enabled
(by writing to
the enable bit)
Measure event
(capture) occurs
Measure event
(capture)
TIN interrupt request due to
external event input
TIO interrupt request due
to underflow
TIN interrupt request due to
external event input
DMA transfer request due
to underflow