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T IME R A
7751 Group User’s Manual
5–22
5.4 Event counter mode
5.4.1 Setting for event counter mode
Figures 5.4.2 and 5.4.3 show an initial setting example for registers relevant to the event counter mode.
Note that when using interrupts, set up to enable the interrupts. For details, refer to
“Chapter 4. INTERRUPTS.”
Fig. 5.4.2 Initial setting example for registers relevant to event counter mode (1)
6
The counter divides the count source frequency by n + 1
when down-counting, or by FFFF
16
– n + 1 when up-
counting.
Continue to
Figure 5.4.3
on next page.
b7
b0
1
0
0
Selecting event counter mode and each function
Timer Ai mode register (i = 0 to 4)
(Addresses 56
16
to 5A
16
)
Pulse output function select bit
0: No pulse output
1: Pulse output
Count polarity select bit
0: Counts at falling edge of external signal.
1: Counts at rising edge of external signal.
Up-down switching factor select bit
0: Contents of up-down register
1: Input signal to TAi
OUT
pin
: It may be either “0” or “1.”
Selection of event counter mode
Setting divide ratio
(b15)
b7
b0
Can be set to
“
0000
16
”
to
“
FFFF
16
”
(n).
(b8)
b7
b0
Timer A0 register (Addresses 47
16
, 46
16
)
Timer A1 register (Addresses 49
16
, 48
16
)
Timer A2 register (Addresses 4B
16
, 4A
16
)
Timer A3 register (Addresses 4D
16
, 4C
16
)
Timer A4 register (Addresses 4F
16
, 4E
16
)
b7
b0
Setting up–down register
Up–down register (Address 44
16
)
Timer A0 up–down bit
Timer A1 up–down bit
Timer A2 up–down bit
Timer A3 up–down bit
Timer A4 up–down bit
Timer A2 two–phase pulse signal processing select bit
Timer A3 two–phase pulse signal processing select bit
Timer A4 two–phase pulse signal processing select bit
Set the corresponding up–down bit when the contents of
the up down register are selected as the up down
switching factor.
Set the corresponding bit to “1” when the two–phase pulse
signal processing function is selected for timers A2 to A4.
0: Down–count
1: Up–count
0: Two–phase pulse signal processing
function disabled
1: Two–phase pulse signal processing
function enabled
–
–