M16C80 Datasheet, PDF(121/358 Page) Renesas Technology Corp – RENESAS 16-BIT SINGLE-CHIP MICROCOMPUTER M16C FAMILY / M16C/80 SERIES

English

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

M16C80 Datasheet, PDF (121/358 Pages) Renesas Technology Corp – RENESAS 16-BIT SINGLE-CHIP MICROCOMPUTER M16C FAMILY / M16C/80 SERIES

◁

M16C/80 Group

14. Timer B

(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 14.3)

Figure 14.6 shows the timer Bi mode register in pulse period/pulse width measurement mode. Figure

14.7 shows the operation timing when measuring a pulse period. Figure 14.8 shows the operation timing

when measuring a pulse width.

Table 14.3 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

pulse's effective edge and the timer continues counting

Count start condition

Count stop condition

Count start flag is set (= 1)

Count start flag is reset (= 0)

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

â¢ Timer overflow. When an overflow occurs, the timer Bi overflow flag set to â1â

simultaneously. The timer Bi overflow flag cleared to â0â by writing to the

timer mode register at the next count timing or later after the timer Bi overflow

flag was set to "1". At this time, make sure the timer start flag is set to "1".

TBiIN pin function

Measurement pulse input (Set the corresponding function select register A to I/O port.)

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.

Timer Bi mode register

b7 b6 b5 b4 b3 b2 b1 b0

10

Symbol

Address

TBiMR(i = 0 to 5) 035B16 to 035D16

031B16 to 031D16

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 (Set to â0â in pulse period/pulse width measurement mode; i = 0, 3)

(Note 2)

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

When write, set "0". When read, its content is 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: This flag is indeterminate after reset. When the timer Bi start flag = 1, the timer Bi overflow flag is

cleared to "0" by writing to the timer Bi mode register at the next count timing or later after the timer Bi

overflow flag was set to "1". The Timer Bi overflow flag cannot be set to "1" in a program.

Note 2: Timer B0, timer B3.

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

Figure 14.6 Timer Bi mode register in pulse period/pulse width measurement mode

Rev.1.00 Aug. 02, 2005 Page 110 of 329

REJ09B0187-0100

▷