M16C62_M Datasheet, PDF(113/615 Page) Renesas Technology Corp – 16-BIT SINGLE-CHIP MICROCOMPUTER M16C FAMILY / M16C/60 SERIES

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M16C62_M Datasheet, PDF (113/615 Pages) Renesas Technology Corp – 16-BIT SINGLE-CHIP MICROCOMPUTER M16C FAMILY / M16C/60 SERIES

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Timer B

Mitsubishi microcomputers

M16C / 62A Group

SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER

(3) Pulse period/pulse width measurement mode

In this mode, the timer measures the pulse period or pulse width of an external signal. (See Table 1.14.8.)

Figure 1.14.19 shows the timer Bi mode register in pulse period/pulse width measurement mode. Figure

1.14.20 shows the operation timing when measuring a pulse period. Figure 1.14.21 shows the operation

timing when measuring a pulse width.

Table 1.14.8. Timer specifications in pulse period/pulse width measurement mode

Item

Specification

Count source

f1, f8, f32, fC32

Count operation

â¢ Up count

â¢ Counter value â000016â is transferred to reload register at measurement

pulse's effective edge and the timer continues counting

Count start condition

Count start flag is set (= 1)

Count stop condition

Count start flag is reset (= 0)

Interrupt request generation timing â¢ When measurement pulse's effective edge is input (Note 1)

â¢ When an overflow occurs. (Simultaneously, the timer Bi overflow flag

changes to â1â. The timer Bi overflow flag changes to â0â when the count

start flag is â1â and a value is written to the timer Bi mode register.)

TBiIN pin function

Measurement pulse input

Read from timer

When timer Bi register is read, it indicates the reload registerâs content

(measurement result) (Note 2)

Write to timer

Cannot be written to

Note 1: An interrupt request is not generated when the first effective edge is input after the timer has started counting.

Note 2: The value read out from the timer Bi register is indeterminate until the second effective edge is input

after the timer has started counting.

Timer Bi mode register

b7 b6 b5 b4 b3 b2 b1 b0

10

Symbol

Address

TBiMR(i=0 to 5) 039B16 to 039D16

035B16 to 035D16

When reset

00XX00002

00XX00002

Bit symbol

TMOD0

TMOD1

Bit name

Operation mode

select bit

Function

b1 b0

1 0 : Pulse period / pulse width

measurement mode

RW

MR0

MR1

Measurement mode

select bit

b3 b2

0 0 : Pulse period measurement (Interval between

measurement pulse's falling edge to falling edge)

0 1 : Pulse period measurement (Interval between

measurement pulse's rising edge to rising edge)

1 0 : Pulse width measurement (Interval between

measurement pulse's falling edge to rising edge,

and between rising edge to falling edge)

1 1 : Must not be set.

MR2

0 (Must always be â0â in pulse period/pulse width measurement mode; i = 0, 3)

(Note 2)

Nothing is assigned (i = 1, 2, 4, 5).

In an attempt to write to this bit, write â0â. The value, if read, turns out to be

indeterminate.

(Note 3)

MR3

Timer Bi overflow

flag ( Note 1)

0 : Timer did not overflow

1 : Timer has overflowed

TCK0

TCK1

Count source

select bit

b7 b6

0 0 : f1

0 1 : f8

1 0 : f32

1 1 : fC32

Note 1: It is indeterminate when reset. The timer Bi overflow flag changes to â0â when the count start flag is â1â

and a value is written to the timer Bi mode register. This flag cannot be set to â1â by software.

Note 2: Timer B0, timer B3.

Note 3: Timer B1, timer B2, timer B4, timer B5.

Figure 1.14.19. Timer Bi mode register in pulse period/pulse width measurement mode

1-94

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