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M30245 Group
2.2.9 Operation of Timer A (one-shot timer mode)
In one-shot timer mode, choose functions from those listed in Table 2.2.9. Operations of the circled items
are described below. Figure 2.2.20 shows the operation timing, and Figures 2.2.21 shows the set-up
procedure.
Table 2.2.9. Choosed functions
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Operation
Count start flag
Write signal to
one-shot start flag
One-shot pulse output
from TAi
pin
OUT
Timer Ai interrupt
request bit
Figure 2.2.20. Operation timing of one-shot mode
Rev.2.00 Oct 16, 2006
REJ09B0340-0200
Item
Count source
O
Internal count source (f
Pulse output function
No pulses output
O
Pulses output
Count start condition
External trigger input (falling edge of input signal to the TAi
External trigger input (rising edge of input signal to the TAi
Timer overflow (TAj/TAk overflow)
O
Writing "1" to the one-shot start flag
Note: j = i – 1, but j = 4 when i = 0; k = i + 1, but k = 0 when i = 4.
(1) Setting the one-shot start flag to "1" with the count start flag set to "1" causes the counter to
perform a down count on the count source. At this time, the TAi
(2) The instant the value of the counter becomes "0000
and the counter reloads the content of the reload register and stops counting. At this time, the
timer Ai interrupt request bit goes to "1".
(3) If a trigger occurs while a count is in progress, the counter reloads the value in the reload
register again and continues counting. The reload timing is in step with the next count source
input after the trigger.
(4) Setting the count start flag to "0" causes the counter to stop and to reload the content of the
reload register. Also, the TAi
request bit goes to "1".
n = reload register content
FFFF
16
(1) Start count
n
0001
16
Set to "1" by software
"1"
"0"
1 / f
"H"
"L"
"1"
"0"
page 26 of 354
/ f
/ f
/ fc
1
8
32
pin outputs an "L" level. At this time, the timer Ai interrupt
OUT
(2) Stop count
(3) Start count
Reload
X (n)
i
Cleared to "0" when interrupt request is accepted, or cleared by software
Set-up
)
32
pin)
IN
pin)
IN
pin outputs an "H" level.
OUT
", the TAi
pin outputs an "L" level,
16
OUT
Start count
Reload
Cleared to "0" by software
1 / f
X (n+1)
i
2. Timer A
(4) Stop count
Reload
Time
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