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M306V5ME-XXXSP
M306V5EESP
MITSUBISHI MICROCOMPUTERS
SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER with CLOSED CAPTION DECODER
and ON-SCREEN DISPLAY CONTROLLER
84
Rev. 1.0
Table 2.10.7 Timer specifications in pulse period/pulse width measurement mode
Notes 1: An interrupt request is not generated when the first effective edge is input after the timer has started counting.
2: The value read out from the timer B0 register is indeterminate until the second effective edge is input after the timer.
(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 2.10.7)
Figure 2.10.23 shows the timer B0 mode register in pulse period/pulse width measurement mode. Figure
2.10.24 shows the operation timing when measuring a pulse period. Figure 2.10.25 shows the operation
timing when measuring a pulse width.
Item
Specification
Count source
f1, f8, f32
Count operation
Up count
Counter value “000016” 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 When measurement pulse's effective edge is input (Note 1)
When an overflow occurs. (Simultaneously, the timer Bi overflow flag changes to “1”.
The timer B0 overflow flag changes to “0” when the count start flag is “1” and a value
is written to the timer B0 mode register.)
TB0IN pin function
Measurement pulse input
Read from timer
When timer B0 register is read, it indicates the reload register’s content
(measurement result) (Note 2)
Write to timer
Cannot be written to
Figure 2.10.23 Timer B0 mode register in pulse period/pulse width measurement mode
Timer B0 mode register
SymbolAddressWhen reset
TB0MR039B16
00?X00002
Bit name
Bit symbol
W
R
b7b6b5b4b3b2b1b0
Operation mode
select bit
1 0 : Pulse period / pulse width
measurement mode
b1 b0
TMOD1
TMOD0
MR0
Measurement mode
select bit
MR2
MR1
MR3
TCK1
TCK0
0
1
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
Function
b3 b2
Count source
select bit
Timer Bi overflow
flag ( Note 1)
0 : Timer did not overflow
1 : Timer has overflowed
0 0 : f1
0 1 : f8
1 0 : f32
1 1 : Do not set
b7 b6
Note: The timer B0 overflow flag changes to “0” when the count start flag is “1” and a value is written to the
timer B0 mode register. This flag cannot be set to “1” by software.
0: Fixed to “0” in pulse period/pulse width measurement mode