參數(shù)資料
型號: M37481M8T-297FP
廠商: Mitsubishi Electric Corporation
英文描述: SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER
中文描述: 單芯片8位CMOS微機
文件頁數(shù): 21/97頁
文件大?。?/td> 1076K
代理商: M37481M8T-297FP
21
MITSUBISHI MICROCOMPUTERS
7480/7481 GROUP
SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER
PRELIMINARY
Notice: This is not a final specification.
Some parametric limits are subject to change.
the timer value provided before the start of measurement.
Figure 21 shows a timing diagram in the pulse cycle measurement
mode.
(4) Pulse Width Measurement Mode
G
Mode Selection
This mode is selected by setting b2, b1 and b0 of TXM or TYM
to “011”.
G
Count Source Selection
The count source is f(X
IN
)/2, f(X
IN
)/8 or f(X
IN
)/16.
G
Interrupt
The underflow interrupt is the same as the timer event count
mode. Set b2 or b3 of IREQ2 to “1” as soon as pulse width
measurement is completed.
G
Explanation of Operation
While a timer operation stops
Select a timer count source. Next, select a pulse width to be
measured. A timer counts a period from a falling edge to a rising
edge of the CNTR
0
/CNTR
1
pin input (“L” period) when b2 or b3
of EG is “1”. A timer counts a period from a rising edge to a fall-
ing edge of the CNTR
0
/CNTR
1
pin input (“H” period) when b2 or
b3 of EG is set to “0”.
While a timer operation is enabled
At setting b0 and b1 of TXYCON to “0”, a timer starts to mea-
sure a pulse width, and starts to count down from the count
value provided before measurement. When the active edge is
detected at measurement completion, 1’s complement of the
timer value is set in the timer latch. When the active edge is de-
tected at measurement completion or measurement start,
“FFFF
16
” is set in the timer. When a timer underflows, a timer X
or timer Y interrupt occurs, and “FFFF
16
” is set in the timer.
A measurement value is held until the next measurement is
completed. In this mode, set the port in common with the
CNTR
0
/CNTR
1
pin as an input port.
G
Interrupt
The timer underflow interrupt is the same as the timer event
count mode.
G
Explanation of Operation
This operation is the same as the timer event count mode ex-
cept that a timer outputs a pulse from the CNTR
0
/CNTR
1
pin in
which the polarity of output level is inverted at each timer
underflow. When the CNTR
0
edge selection bit (b2) or CNTR
1
edge selection bit (b3) of EG is “0”, the output of the CNTR
0
/
CNTR
1
pin is started with an “H” level output. When b2 or b3 of
EG is “1”, the output of this pin is started with an “L” level. In this
mode, set the port in common with the CNTR
0
/CNTR
1
pin as an
output port.
I
Note
While a timer operation stops
The output level of the CNTR
0
/CNTR
1
pin is initialized to the value
set in the CNTR
0
edge selection bit or CNTR
1
edge selection bit
by writing to the timer.
While a timer operation is enabled
The output level of the CNTR
0
/CNTR
1
pin is inverted by changing
the CNTR
0
edge selection bit or CNTR
1
edge selection bit.
Figure 20 shows a timing diagram in the pulse output mode.
(3) Pulse Cycle Measurement Mode
G
Mode Selection
This mode is selected by setting b2, b1 and b0 of TXM or TYM
to “010”.
G
Count Source Selection
The count source is f(X
IN
)/2, f(XI
N
)/8 or f(X
IN
)/16.
G
Interrupt
The underflow interrupt is the same as the timer event count
mode. Set b2 or b3 of IREQ2 to “1” as soon as the pulse cycle
measurement is completed.
G
Explanation of Operation
While a timer operation stops
Select a timer count source. Next, select a pulse cycle to be
measured. When b2 or b3 of EG is “0”, a timer counts a period
from a falling edge to a falling edge of the CNTR
0
/CNTR
1
pin in-
put.
When b2 or b3 of EG is “1”, a timer counts a period from a ris-
ing edge to a rising edge of the CNRT
0
/CNTR
1
pin input.
While a timer operation is enabled
At setting b0 and b1 of TXYCON to “0”, a timer starts to mea-
sure the pulse cycle, and starts to count down from the count
value provided before measurement. When an active edge is
detected at measurement completion or measurement start, 1's
complement of the timer value is set to the timer latch and
“FFFF
16
” is set in the timer.
When a timer underflows, a timer X or timer Y interrupt occurs,
and “FFFF
16
” is set in the timer. A measurement value is held
until the next measurement is completed. In this mode, set the
port in common with the CNTR
0
/CNTR
1
pin as an input port.
I
Note
The timer value cannot be read in this mode. A timer value can be
set while a timer operation stops (no measurement).
Since the timer latch of this mode becomes read only, do not per-
form a write operation during measurement.
The timer is set to “FFFF
16
” only when the timer underflows or the
active edge of pulse cycle measurement is detected.
Accordingly, the timer value at a start of measurement depends on
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