M16C6K9 Datasheet, PDF (95/292 Pages) Renesas Technology Corp – SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER

M16C/6K9 Group
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.FB-8)
Fig.FB-19 shows the timer Bi mode register in pulse period/pulse width measurement mode. Fig.FB-20
shows the operation timing when measuring a pulse period. Fig.FB-21 shows the operation timing when
measuring a pulse width.
Table.FB-8 Timer specifications in pulse period/pulse width measurement mode
Item
Specification
Count source
f1, f8, f32, fC32
Count operation
•Up count
•At measurement pulse's effective edge, after the count value is transferred
to reload register, it is cleared to "000016" and then continues counting.
Count start condition
Count start flag is set (= 1)
Count stop condition
Count start flag is reset (= 0)
Interrupt request generation timing •When measurement pulse's effective edge is input (Note 1)
•When an overflow occurs. (Simultaneously, the timer Bi overflow flag becomes
“1”. The timer Bi overflow flag becomes “0” when the count start flag is “1”
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 register’s 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: After count starts, the value read out from the timer Bi register is indeterminate until the second
effective edge is input .
Timer Bi mode register
b7 b6 b5 b4 b3 b2 b1 b0
10
Symbol
TBiMR(i=0 to 5)
Address
039B16 to 039D16
035B16 to 035D16
When reset
00XX00002
00XX00002
Bit symbol
TMOD0
TMOD1
Bit name
Operation mode
selection bits
MR0
Measurement mode
selection bits
MR1
Function
b1 b0
1 0 : Pulse period / pulse width
measurement mode
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 : Inhibited
RW
MR2
MR3
TCK0
TCK1
0 (Fixed to “0” in pulse period/pulse width measurement mode; i = 0, 3)
Nothing is assigned (i = 1, 2, 4, 5).
In an attempt to write to this bit, write “0”. The value, if read, turns out to be
indeterminate.
Timer Bi overflow
flag ( Note 1)
Count source
selection bits
0 : Timer did not overflow
1 : Timer has overflowed
b7 b6
0 0 : f1
0 1 : f8
1 0 : f32
1 1 : fC32
(Note 2)
(Note 3)
Note 1: The timer Bi overflow flag becomes “0” when the count start flag is “1” and a value is written to the
timer Bi mode register. This flag cannot be set to “1” by software.
Note 2: Timer B0, timer B3.
Note 3: Timer B1, timer B2, timer B4, timer B5.
Fig.FB-19 Timer Bi mode register in pulse period/pulse width measurement mode
Rev.1.00 Jun 06, 2003 page 95 of 290