7906 datasheet(173/531 Pages) RENESAS

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7906 Group User’s Manual Rev.2.0

8-22

TIMER B

8.5 Pulse period/Pulse width measurement mode

8.5.1 Setting for pulse period/pulse width measurement mode

Figure 8.5.2 shows an initial setting example for registers relevant to the pulse period/pulse width measurement

mode.

Note that when using interrupts, set up to enable the interrupts. For details, refer to “CHAPTER 6.

INTERRUPTS.”

Fig. 8.5.2 Initial setting example for registers relevant to pulse period/pulse width measurement mode

Count starts.

Measurement mode select bits

Selecting pulse period/pulse width measurement mode and each function

Timer Bi mode register (i = 0 to 2)

(Addresses 5B16 to 5D16) (Note 1)

Setting count start bit to “1”

Count start register 0

(Address 4016)

Timer B0 count start bit

Timer B1 count start bit

Timer B2 count start bit

b3 b2

Setting interrupt priority level

Timer Bi interrupt control register (i = 0 to 2)

(Addresses 7A16 to 7C16)

Interrupt priority level select bits

When using interrupts, set these bits to one of levels 1 to 7.

When disabling interrupts, set these bits to level 0.

Count source select bits

b7b6

Timer Bi overflow flag (Note 2)

0: No overflow

1: Overflowed

0 0 : Pulse period measurement (Interval between falling edges

of measurement pulse)

0 1 : Pulse period measurement (Interval between rising edges

of measurement pulse)

1 0 : Pulse width measurement

1 1 : Do not select.

0 0 : f2

0 1 : f16

1 0 : f64

1 1 : f512

Notes 1: When using timer B2, be sure to clear the timer B2 clock source select bit (See Figure 8.4.2.) to “0.”

2: The timer Bi overflow flag is a read-only bit. This bit is undefined after reset. When a value is written to the timer Bi mode register

with the count start bit = “1,” this bit will be cleared to “0.”

3: By using bits 0 to 2 of the port P2 pin function control register (address AE16), be sure to set the pin allocation. (See Figure 8.2.5.)

Selection of pulse period/pulse width measurement mode

Count-type select bit

0: Counter clear type

1: Free-run type

Setting port P2 direction register

Port P2 direction register (Address 816)

Clear the coressponding bit to “0.”

Pin TB0IN

Pin TB1IN

Pin TB2IN

When a pin is allocated to a port P2 pin (Note 3)

Setting port P5 direction register

Port P5 direction register (Address D16)

Clear the coressponding bit to “0.”

Pin TB0IN

Pin TB1IN

Pin TB2IN

When a pin is allocated to a port P5 pin (Note 3)

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