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CHAPTER 6 16-BIT TIMER/EVENT COUNTER 00
Preliminary User’s Manual U16846EJ1V0UD
126
(3) Pulse width measurement with free-running counter and two capture registers
When 16-bit timer counter 00 (TM00) is operated in free-running mode, it is possible to measure the pulse width
of the signal input to the TI000 pin.
When the rising or falling edge specified by bits 4 and 5 (ES000 and ES001) of prescaler mode register 00
(PRM00) is input to the TI000 pin, the value of TM00 is taken into 16-bit timer capture/compare register 010
(CR010) and an interrupt request signal (INTTM010) is set.
Also, when the inverse edge to that of the capture operation is input into CR010, the value of TM00 is taken into
16-bit timer capture/compare register 000 (CR000).
Sampling is performed at the interval selected by prescaler mode register 00 (PRM00), and a capture operation is
only performed when the valid level of the TI000 pin is detected twice, thus eliminating noise with a short pulse
width.
Figure 6-22. Control Register Settings for Pulse Width Measurement with Free-Running Counter and
Two Capture Registers (with Rising Edge Specified)
(a) 16-bit timer mode control register 00 (TMC00)
7
0
6
0
5
0
4
0
TMC003
0
TMC002
1
TMC001
0/1
OVF00
0
TMC00
Free-running mode
(b) Capture/compare control register 00 (CRC00)
7
0
6
0
5
0
4
0
3
0
CRC002
1
CRC001
1
CRC000
1
CRC00
CR000 used as capture register
Captures to CR000 at inverse edge
to valid edge of TI000.
CR010 used as capture register
(c) Prescaler mode register 00 (PRM00)
ES101
0/1
ES100
0/1
ES001
0
ES000
1
3
0
2
0
PRM001
0/1
PRM000
0/1
PRM00
Selects count clock (setting “11” is prohibited).
Specifies rising edge for pulse width detection.
Setting invalid (setting “10” is prohibited.)
Remark 0/1: Setting 0 or 1 allows another function to be used simultaneously with pulse width measurement.
See the description of the respective control registers for details.