UPD78F9500MA-CAC-A Datasheet, PDF (108/342 Pages) Renesas Technology Corp – 8-Bit Single-Chip Microcontrollers

CHAPTER 6 16-BIT TIMER/EVENT COUNTER 00 (μPD78F920x ONLY)
6.4.3 Pulse width measurement operations
It is possible to measure the pulse width of the signals input to the TI000 pin and TI010 pin using 16-bit timer
counter 00 (TM00).
There are two measurement methods: measuring with TM00 used in free-running mode, and measuring by
restarting the timer in synchronization with the edge of the signal input to the TI000 pin.
When an interrupt occurs, necessary pulse width is calculable by reading the valied value of the capture register.
The capture operation is not performed until the signal pulse width is sampled in the count clock cycle selected by
prescaler mode register 00 (PRM00) and the valid level of the TI000 or TI010 pin is detected twice, thus eliminating
noise with a short pulse width ( see Figure 6-18 ).
Figure 6-18. CR010 Capture Operation with Rising Edge Specified
Count clock
TM00
N−3
N−2
N−1
N
N+1
TI000
Rising edge detection
CR010
N
INTTM010
Setting
The basic operation setting procedure is as follows.
<1> Set the CRC00 register (see Figures 6-19, 6-22, 6-24, and 6-26 for the set value).
<2> Set the count clock by using the PRM00 register.
<3> Set the TMC00 register to start the operation (see Figures 6-19, 6-22, 6-24, and 6-26 for the set value).
Caution To use two capture registers, set the TI000 and TI010 pins.
Remarks 1. For the setting of the TI000 (or TI010) pin, see 6.3 (5) Port mode register 2 (PM2) and port mode
control register 2 (PMC2).
2. For how to enable the INTTM000 (or INTTM010) interrupt, see CHAPTER 10 INTERRUPT
FUNCTIONS.
(1) Pulse width measurement with free-running counter and one capture register
Specify both the rising and falling edges as the valid edges of the TI000 pin, by using bits 4 and 5 (ES000 and
ES010) of PRM00.
When 16-bit timer counter 00 (TM00) is operated in free-running mode, and the valid edge specified by
PRM00 is input, the value of TM00 is taken into 16-bit timer capture/compare register 010 (CR010) and an
external interrupt request signal (INTTM010) is set.
Sampling is performed using the count clock selected by 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.
Caution The measurable pulse width in this operation example is up to 1 cycle of the timer counter.
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User’s Manual U18172EJ3V0UD