
CHAPTER 6 16-BIT TIMER/EVENT COUNTERS 00 AND 01
Preliminary User’s Manual U16228EJ1V0UD
167
6.4.3 Pulse width measurement operations
It is possible to measure the pulse width of the signals input to the TI00n pin and TI01n pin using 16-bit timer
counter 0n (TM0n).
There are two measurement methods: measuring with TM0n used in free-running mode, and measuring by
restarting the timer in synchronization with the edge of the signal input to the TI00n pin.
(1) Pulse width measurement with free-running counter and one capture register
When 16-bit timer counter 0n (TM0n) is operated in free-running mode (see register settings in Figure 6-18), and
the edge specified by prescaler mode register 0n (PRM0n) is input to the TI00n pin, the value of TM0n is taken
into 16-bit timer capture/compare register 01n (CR01n) and an external interrupt request signal (INTTM01n) is
set.
Any of three edges
rising, falling, or both edgescan be selected using bits 4 and 5 (ES0n0 and ES0n1) of
PRM0n.
For valid edge detection, sampling is performed using the count clock selected by PRM0n, and a capture
operation is only performed when a valid level is detected twice, thus eliminating noise with a short pulse width.
Figure 6-18. Control Register Settings for Pulse Width Measurement with Free-Running Counter
and One Capture Register
(a) 16-bit timer mode control register 0n (TMC0n)
0000
TMC0n3
0
TMC0n2
1
TMC0n1
0/1
OVF0n
0
TMC0n
Free-running mode
(b) Capture/compare control register 0n (CRC0n)
00000
CRC0n2
1
CRC0n1
0/1
CRC0n0
0
CRC0n
CR00n used as compare register
CR01n used as capture register
Remark
0/1: Setting 0 or 1 allows another function to be used simultaneously with pulse width measurement.
See Figures 6-3 to 6-6.
n = 0:
PD780131, 780132
n = 0, 1:
PD780133, 780134, 78F0134, 780136, 780138, 78F0138