M16C30L Datasheet, PDF(92/166 Page) Renesas Technology Corp – SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER

English

English German Russian Spanish Italian Polish Chinese Japanese Korean French Portuguese	Language :

M16C30L Datasheet, PDF (92/166 Pages) Renesas Technology Corp – SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER

◁

Timer B

Mitsubishi microcomputers

M16C / 30L 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

Count operation

f1, f8, f32, fC32

â¢ Up count

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

Count start condition

pulse's effective edge and the timer continues counting

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

Read from timer

Measurement pulse input

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

Symbol

TBiMR(i=1, 2)

Address

039C16, 039D16

When reset

00XX00002

Bit symbol

Bit name

TMOD0

TMOD1

Operation mode

select bit

Function

b1 b0

1 0 : Pulse period / pulse width

measurement mode

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.

Nothing is assigned.

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

indeterminate.

MR3

Timer Bi overflow

flag (Note)

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: 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.

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

▷