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CHAPTER 9 TIMER/COUNTER FUNCTION (REAL-TIME PULSE UNIT)
(1) Timer 3 (TM3)
TM3 functions as a 16-bit free-running timer or as an event counter for an external signal. Besides being
mainly used for cycle measurement, TM3 can be used as pulse output.
TM3 is read-only in 16-bit units.
Cautions 1. The TM3 register can only be read. If writing is performed to the TM3 register, the
subsequent operation is undefined.
2. If the TM3CAE bit of the TMC30 register is cleared (0), a reset is performed
asynchronously.
3. Continuous reading of TM3 is prohibited. If TM3 is continuously read, the second read
value may differ from the actual value.
15
14 13 12
TM3
TM3 performs the count-up operations of an internal count clock or external count clock. Timer starting and
stopping are controlled by the TM3CE bit of timer control register 30 (TMC30).
The internal or external count clock is selected by the ETI bit of timer control register 31 (TMC31).
(a) Selection of the external count clock
TM3 operates as an event counter.
When the ETI bit of timer control register 31 (TMC31) is set (1), TM3 counts the valid edges of the
external clock input (TI3), synchronized with the internal count clock. The valid edge is specified by valid
edge selection register (SESC).
Caution If the INTP30, TI3, and TCLR3 pins are used as the TI3 and TCLR3, either mask the
INTP30 interrupt or set CC3n in compare mode (n = 0, 1).
Figure 9-83. Timer 3 (TM3)
11 10
9
8
7
6
User's Manual U14492EJ3V0UD
5
4
3
2
1
0
Address
Initial value
FFFFF680H
0000H
379
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