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CHAPTER 6 16-BIT TIMER/EVENT COUNTER
Preliminary User’s Manual U13420EJ2V0UM00
6.5.3 Pulse width measurement operations
It is possible to measure the pulse width of the signals input to the TI00/TO0/P20 pin and TI01/P21 pin using
16-bit timer/counter 0 (TM0).
There are two measurement methods: measuring with TM0 used in free-running mode, and measuring by restarting
the timer in synchronization with the edge of the signal input to the TI00/TO0/P20 pin.
(1) Pulse width measurement with free-running counter and one capture register
When 16-bit timer/counter 0 (TM0) is operated in free-running mode (see register settings in Figure 6-11), and
the edge specified by prescaler mode register 0 (PRM0) is input to the TI00/TO0/P20 pin, the value of TM0 is
taken into 16-bit timer capture/compare register 01 (CR01) and an external interrupt request signal (INTTM01)
is set.
Any of three edges can be selected—rising, falling, or both edges—specified by means of bits 6 and 7 (ES10
and ES11) of PRM0.
For valid edge detection, sampling is performed at the count clock selected by PRM0, and a capture operation
is only performed when a valid level is detected twice, thus eliminating noise with a short pulse width.
Figure 6-11. Control Register Settings for Pulse Width Measurement with Free-Running Counter
and One Capture Register
(a) 16-bit timer mode control register 0 (TMC0)
(b) Capture/compare control register 0 (CRC0)
Remark
0/1: Setting 0 or 1 allows another function to be used simultaneously with pulse width measurement.
See Figures 6-2 and 6-3.
0
0
0
0
TMC03
0
TMC02
1
TMC01
0/1
OVF0
0
TMC0
Free running mode
0
0
0
0
0
CRC02
1
CRC01
0/1
CRC00
0
CRC0
CR00 as compare register
CR01 as capture register
Содержание mPD780065 Series
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