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2.2.2 Operation of Timer A (timer mode)
In timer mode, choose functions from those listed in Table 2.2.1. Operations of the circled items are
described below. Figure 2.2.6 shows the operation timing, and Figure 2.2.7 shows the set-up procedure.
Table 2.2.1. Choosed functions
Item
Count source
Pulse output function
Gate function
Operation (1) Setting the count start flag to "1" causes the counter to perform a down count on the count
source.
(2) 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".
(3) Setting the count start flag to "0" causes the counter to hold its value and to stop.
FFFF
n
0000
"1"
Count start flag
"0"
Timer Ai interrupt
"1"
request bit
"0"
Figure 2.2.6. Operation timing of timer mode
Rev.2.00 Oct 16, 2006
REJ09B0340-0200
O
Internal count source (f
O
No pulses output
Pulses output
O
No gate function
Performs count only for the period in which the TAi
Performs count only for the period in which the TAi
n = reload register content
16
(1) Start count
16
Set to "1" by software
Cleared to "0" when interrupt request is accepted, or cleared by software
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Set-up
/ f
/ f
/ fc
)
1
8
32
32
(2) Underflow
Cleared to "0" by
software
pin is at "L" level
IN
pin is at "H" level
IN
(3) Stop count
Start count again
Time
Set to "1" by software
2. Timer A
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