7480 Datasheet, PDF (22/98 Pages) Bi technologies – 7/8 Diameter 5-Turn Wirewound Precision Potentiometer

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MITSUBISHI MICROCOMPUTERS
7480/7481 GROUP
SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER
q Interrupt
The timer underflow interrupt is the same as the timer event
count mode.
q Explanation of Operation
This operation is the same as the timer event count mode ex-
cept that a timer outputs a pulse from the CNTR0/CNTR1 pin in
which the polarity of output level is inverted at each timer
underflow. When the CNTR0 edge selection bit (b2) or CNTR1
edge selection bit (b3) of EG is “0”, the output of the CNTR0/
CNTR1 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 CNTR0/CNTR1 pin as an
output port.
s Note
While a timer operation stops
The output level of the CNTR0/CNTR1 pin is initialized to the value
set in the CNTR0 edge selection bit or CNTR1 edge selection bit
by writing to the timer.
While a timer operation is enabled
The output level of the CNTR0/CNTR1 pin is inverted by changing
the CNTR0 edge selection bit or CNTR1 edge selection bit.
Figure 20 shows a timing diagram in the pulse output mode.
(3) Pulse Cycle Measurement Mode
q Mode Selection
This mode is selected by setting b2, b1 and b0 of TXM or TYM
to “010”.
q Count Source Selection
The count source is f(XIN)/2, f(XIN)/8 or f(XIN)/16.
q 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.
q 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 CNTR0/CNTR1 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 CNRT0/CNTR1 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
“FFFF16” is set in the timer.
When a timer underflows, a timer X or timer Y interrupt occurs,
and “FFFF16” 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 CNTR0/CNTR1 pin as an input port.
s 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 “FFFF16” 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
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
q Mode Selection
This mode is selected by setting b2, b1 and b0 of TXM or TYM
to “011”.
q Count Source Selection
The count source is f(XIN)/2, f(XIN)/8 or f(XIN)/16.
q 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.
q 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 CNTR0/CNTR1 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 CNTR0/CNTR1 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,
“FFFF16” is set in the timer. When a timer underflows, a timer X
or timer Y interrupt occurs, and “FFFF16” 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
CNTR0/CNTR1 pin as an input port.
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