Two-Phase Pulse Signal Process In Event Counter Mode With Multiply-By-4 Mode Selected - Renesas M16C Series User Manual

M30240 Group
2.2.2.7 2-phase pulse signal process in event counter mode with Multiply-by-4 mode selected
In processing 2-phase pulse signals in event counter mode, select functions from those listed in Table
2.7 . An example using the indicated options is described below. Figure 2.19 shows the operation timing
and Figure 2.20 shows the set-up procedure.
Table 2.7: Timer A 2-phase pulse signal process in event counter mode, multiply by 4 functions
Item
Count operation type
O
Note: Only Timer A3 can select between normal and 4-multiplication processing.
Timer A2 is used only for normal processes.
Timer A4 is used only 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 con-
tinues. At this time, the interrupt request bit goes to "1".
(3) Even if an overflow occurs, the content of the reload register is not reloaded, but the count contin-
ues. At this time, the interrupt request bit goes to "1".
Note: The up count or down count conditions are shown in Table 2.8 .
Table 2.8: Up count or Down count conditions
Input signal to the
TAiOUT pin
"H" level
"L" level
Up count
Rising
Falling
Count start flag
Timer Ai interrupt
request bit
Figure 2.19: Operation timing of 2-phase pulse signal process in event counter mode, multiply by 4
Rev.1.00 Sep 24, 2003 Page 159 of 360
Set-up
Reload type
Free-run type
Input signal to
the TAiIN pin
Rising
Falling
"L" level
"H" level
(1) Start count
"H"
TAi
OUT
"L"
"H"
TAi
IN
"L"
FFFF
16
0000
16
Set to "1" by software
"1"
"0"
Cleared to "0" when interrupt request is accepted, or cleared by software
"1"
"0"
Item
Processing 2-phase
pulses (Note)
O
Input signal to the
TAiOUT pin
"H" level
"L" level
Down count
Rising
Falling
(2) Underflow
(3) Overflow
Timer A
Set-up
Normal processing
4-multiplication processing
Input signal to the
TAiIN pin
Falling
Rising
"H" level
"L" level
Time