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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.
Table 2.2.2. Choosed functions
Item
Count source
Pulse output function
Gate function
Operation
(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
(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.
Note
• Make the pulse width of the signal input to the TAi
FFFF
16
n
0000
16
"1"
Count start flag
"0"
"H"
TAiIN pin
input signal
"L"
Timer Ai interrupt
"1"
request bit
"0"
Figure 2.2.8. Operation timing of timer mode, gate function selected
Rev.2.00 Oct 16, 2006
REJ09B0340-0200
O
Internal count source(f
O
No pulses output
Pulses output
No gate function
Performs count only for the period in which the TAi
O
Performs count only for the period in which the TAi
pin inputs at "L" level, the counter holds its value and stops.
IN
n = reload register content
(1) Start count
(2) Stop count
Set to "1" by software
page 14 of 354
Set-up
/ f
/ f
/ fc
)
1
8
32
32
pin inputs at "H" level, the counter per-
IN
pin not less than two cycles of the count source.
IN
(3) Underflow
Cleared to "0" by software
Cleared to "0" when interrupt request is accepted, or cleared by software
2. Timer A
pin is at "L" level
IN
pin is at "H" level
IN
(4) Stop count
Start count again.
Time
Set to "1" by software
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