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M30245 Group
2.2.3 Operation of Timer A (timer mode, gate function selected)
In timer mode, choose functions from those listed in Table 2.2.2. Operations of the circled items are
described below. Figure 2.2.8 shows the operation timing, and Figure 2.2.9 shows the set-up procedure.
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Operation
Note
Count start flag
TAiIN pin
input signal
Timer Ai interrupt
request bit
Figure 2.2.8. Operation timing of timer mode, gate function selected
Rev.2.00 Oct 16, 2006
REJ09B0340-0200
Table 2.2.2. Choosed functions
Item
Count source
O
Internal count source(f
Pulse output function
O
No pulses output
Pulses output
Gate function
No gate function
Performs count only for the period in which the TAi
O
Performs count only for the period in which the TAi
(1) When the count start flag is set to "1" and the TAi
forms a down count on the count source.
(2) When the TAi
pin inputs at "L" level, the counter holds its value and stops.
IN
(3) If an underflow occurs, the content of the reload register is reloaded and the count continues.
At this time, the timer Ai interrupt request bit goes to "1".
(4) Setting the count start flag to "0" causes the counter to hold its value and to stop.
• Make the pulse width of the signal input to the TAi
n = reload register content
FFFF
16
(1) Start count
n
0000
16
Set to "1" by software
"1"
"0"
"H"
"L"
"1"
"0"
page 14 of 354
Set-up
/ f
/ f
/ fc
)
1
8
32
32
IN
pin not less than two cycles of the count source.
IN
(2) Stop count
Cleared to "0" by software
Cleared to "0" when interrupt request is accepted, or cleared by software
pin is at "L" level
IN
pin is at "H" level
IN
pin inputs at "H" level, the counter per-
(3) Underflow
(4) Stop count
Start count again.
Set to "1" by software
2. Timer A
Time
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