Operation - NEC UPD703116 User Manual

9.4.5 Operation

(1) Count operation
Timer 3 can function as a 16-bit free-running timer or as an external signal event counter. The setting for the
type of operation is specified by timer control register 3n (TMC3n) (n = 0, 1).
When it operates as a free-running timer, if the CC30 or CC31 register and the TM3 count value match, an
interrupt signal is generated and the timer output signal (TO3) can be set or reset. Also, a capture operation
that holds the TM3 count value in the CC30 or CC31 register is performed, synchronized with the valid edge
that was detected from the external interrupt request input pin as an external trigger. The capture value is
held until the next capture trigger is generated.
Caution If the INTP30/TI3/TCLR3 pin is used as TI3 or TCLR3, either mask the INTP30 interrupt or set
the CC3n register to compare mode (n = 0, 1).
Count clock
TM3 0000H 0001H
∆
Count start
TM3CE ← 1
CHAPTER 9 TIMER/COUNTER FUNCTION
Figure 9-90. Basic Operation of Timer 3
0002H 0003H FBFEH FBFFH
User's Manual U14492EJ5V0UD
0000H 0001H 0002H
∆ ∆
Count disabled Count start
TM3CE ← 0 TM3CE ← 1
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