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2.2.7 Operation of timer A (two-phase pulse signal process in event counter mode,
normal mode selected)
In processing two-phase pulse signals in event counter mode, choose functions from those listed in Table
2.2.6. Operations of the circled items are described below. Figure 2.2.16 shows the operation timing, and
Figure 2.2.17 shows the set-up procedure.
Table 2.2.6. Choosed functions
Item
Count operation type
Two-phase pulses
process (Note)
Note: Timer A3 alone can be selected. Timer A2 is solely used for normal processes, and timer A4 is solely used for 4
multiplication processes.
Operation
(1) Setting the count start flag to "1" causes the counter to count effective edges of the count
source.
(2) Even if an underflow occurs, the content of the reload register is not reloaded, but the count
continues. At this time, the timer Ai interrupt request bit goes to "1".
(3) Even if an overflow occurs, the content of the reload register is not reloaded, but the count
continues. At this time, the timer Ai interrupt request bit goes to "1".
Note
• The up count or down count conditions are as follows:
If a rising edge is present at the TAi
an up count is performed.
If a falling edge is present at the TAi
a down count is performed.
• Set TAi
IN
"H"
TAi
OUT
"L"
"H"
TAi
IN
"L"
FFFF
16
0000
16
"1"
Count start flag
"0"
"1"
Timer Ai interrupt
request bit
"0"
Note 1: First set to "Reload type" operation. Once the first counting pulse has occurred, the timer may be changed to "Free-Run type".
Figure 2.2.16. Operation timing of two-phase pulse signal process in event counter mode, normal mode selected
Rev.2.00 Oct 16, 2006
REJ09B0340-0200
Reload type
O
Free run type
O
Normal processing
4-multiplication processing
pin and TAi
pin's port direction register to "0".
OUT
(1) Start count
(Note)
Set to "1" by software
page 22 of 354
Set-up
pin when the input signal level to the TAi
IN
pin when the input signal level to the TAi
IN
(2) Underflow
Cleared to "0" when interrupt request is accepted, or cleared by software
2. Timer A
pin is "H",
OUT
pin is "H",
OUT
(3)
Overflow
Time
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