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M30245 Group
2.2.4 Operation of Timer A (timer mode, pulse output function selected)
In timer mode, choose functions from those listed in Table 2.2.3. Operations of the circled items are
described below. Figure 2.2.10 shows the operation timing, and Figures 2.2.11 shows the set-up proce-
dure.
Table 2.2.3. 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". Also, the output polarity of the
TAi
OUT
(3) Setting the count start flag to "0" causes the counter to hold its value and to stop. Also, the
TAi
OUT
FFFF
16
n
0000
16
"1"
Count start flag
"0"
Pulse output from
"H"
TAi
pin
OUT
"L"
Timer Ai interrupt
"1"
request bit
"0"
Figure 2.2.10. Operation timing of timer mode, pulse output function selected
Rev.2.00 Oct 16, 2006
REJ09B0340-0200
O
Internal count source(f
No pulses output
O
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
pin reverses.
pin outputs an "L" level.
n = reload register content
(2) Underflow
(1) Start count
Cleared to "0" by
software
Set to "1" by software
Cleared to "0" when interrupt request is accepted, or cleared by software
page 16 of 354
Set-up
/ f
/ f
/ fc
)
1
8
32
32
(3) Stop count
Start count again
Set to "1" by software
2. Timer A
pin is at "L" level
IN
pin is at "H" level
IN
Time
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