CHAPTER 6 16-BIT TIMER/EVENT COUNTER 00
Preliminary User’s Manual U16898EJ1V0UD
101
(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 ES010) 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 using the count clock cycle selected by prescaler mode register 00 (PRM00), and a
capture operation is only performed when a valid level of the TI000 pin is detected twice, thus eliminating
noise with a short pulse width.
Figure 6-23. 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)
ES110
0/1
ES100
0/1
ES010
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.
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