M30222 Datasheet, PDF (89/237 Pages) Mitsubishi Electric Semiconductor – SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER

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MITSUBISHI MICROCOMPUTERS
Specifications in this manual are tentative and subject to change
M30222 Group
Rev. G
Timer B
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 1.32).
Figure 1.66 shows the Timer Bi mode register in pulse period/pulse width measurement mode. Figure
1.67 shows the operation timing when measuring a pulse period. Figure 1.68 shows the operation timing
when measuring a pulse width.
Usage Precautions
(1) If changing the measurement mode select bit is set after a count is started, the Timer Bi interrupt request
bit goes to “1”.
(2) When the first effective edge is input after a count is started, an indeterminate value is transferred to the
reload register. At this time, Timer Bi interrupt request is not generated.
Table 1.32. Timer specifications in pulse period/pulse width measurement mode
Item
Count source
Count operation
Count start condition
Count stop condition
Interrupt request
generation timing
TBiIN pin function
Read from timer
Write to timer
Specification
f1, f8, f32, fc32
Count up
Counter value 0000₁₆ is transferred to reload register at measurement pulse s effec-
tive edge and the timer continues counting.
Count start flag is set (=1)
Count start flag is reset (=0)
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 Bi overlfow changes to 0 when the count start flag is 1 and the
value is written to another Timer Bi timer mode register).
Measurement pulse input
When Timer Bi register is read, it indicates the reload register s content (measurement
result) (Note 2)
Cannot write to timer
Note 1: An interrupt requst 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.
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