M16C62A Datasheet, PDF(85/242 Page) Mitsubishi Electric Semiconductor – SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER

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M16C62A Datasheet, PDF (85/242 Pages) Mitsubishi Electric Semiconductor – SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER

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Timer B

Mitsubishi microcomputers

M16C / 62A Group (80-pin)

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 1.13.8.)

However, this function cannot be used since timer B1 does not have input port. Figure 1.13.19 shows the

timer Bi mode register in pulse period/pulse width measurement mode. Figure 1.13.20 shows the opera-

tion timing when measuring a pulse period. Figure 1.13.21 shows the operation timing when measuring

a pulse width.

Table 1.13.8. 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. Assume that the count start flag condition is â1â and then the

timer Bi overflow flag becomes â1â. If the timer Bi mode register has a write-

access after next count cycle of the timer from the above condition, the timer

Bi overflow flag becomes â0â.)

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

Bit name

TMOD0

TMOD1

Operation mode

select bit

Function

b1 b0

1 0 : Pulse period / pulse width

measurement mode (Note 4)

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

MR3

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)

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. Assume that the count start flag condition is â1â and then the timer Bi

overflow flag becomes â1â. If the timer Bi mode register has a write access after next count cycle of

the timer from the above condition, the timer Bi overflow flag becomes â0â. 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.

Note 4: Do not set this mode in timer B1 mode register because timer B1 dose not have input port.

Figure 1.13.19. Timer Bi mode register in pulse period/pulse width measurement mode

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