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CHAPTER 6 16-BIT TIMER/EVENT COUNTER 0
Preliminary User’s Manual U16035EJ1V0UM
(2) Measurement of two pulse widths with free-running counter
When the 16-bit timer counter 0 (TM0) is operated in free-running mode (see register settings in
Figure 6-14
),
it is possible to simultaneously measure the pulse widths of the two signals input to the TI00/TO0/P70 pin and
the TI01/P71 pin.
When the edge specified by bits 4 and 5 (ES00 and ES01) of prescaler mode register 0 (PRM0) is input to the
TI00/TO0/P70 pin, the value of TM0 is taken into 16-bit timer capture/compare register 01 (CR01) and an interrupt
request signal (INTTM01) is set.
Also, when the edge specified by bits 6 and 7 (ES10 and ES11) of PRM0 is input to the TI01/P71 pin, the value
of TM0 is taken into 16-bit timer capture/compare register 00 (CR00) and an interrupt request signal (INTTM00)
is set.
Any of three edge can be selected—rising, falling, or both edges—as the valid edges for the TI00/TO0/P70 pin
and the TI01/P71 pin specified by means of bits 4 and 5 (ES00 and ES01) and bits 6 and 7 (ES10 and ES11)
of PRM0, respectively.
For valid edge detection of TI00/TO0/P70 and TI01/P71 pins, sampling is performed at the interval selected by
means of the prescaler mode register 0 (PRM0), and a capture operation is only performed when a valid level
is detected twice, thus eliminating noise with a short pulse width.
Figure 6-14. Control Register Settings for Measurement of Two Pulse Widths with Free-Running Counter
(a) 16-bit timer mode control register 0 (TMC0)
0
0
0
0
TMC03
0
TMC02
1
TMC01
0/1
OVF0
0
TMC0
Free-running mode
(b) Capture/compare control register 0 (CRC0)
0
0
0
0
0
CRC02
1
CRC01
0
CRC00
1
CRC0
CR00 as capture register
Captures valid edge of TI01/P71 pin to CR00
CR01 as capture register
Remark
0/1: Setting 0 or 1 allows another function to be used simultaneously with pulse width measurement.
For details, see
Figure 6-2
.
