Renesas 7700 FAMILY, Руководство пользователя

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TIMER A
7751 Group User’s Manual
5–27
5.4 Event counter mode
(2) Two-phase pulse signal processing function (Timers A2 to A4)
For timers A2 to A4, the two-phase pulse signal processing function is selected by setting the two-
phase pulse signal processing select bits (bits 5 to 7 at address 44
16
) to “1.” (Refer to Figure 5.4.5.)
Figure 5.4.6 shows the timer A2, A3, and A4 mode registers when the two-phase pulse signal
processing function is selected.
With timers selecting the two-phase pulse signal processing function, the timer counts two kinds of
pulses of which phases differ by 90 degrees. There are two types of the two-phase pulse signal
processing: normal processing and quadruple processing. In timers A2 and A3, normal processing
is performed; in timer A4, quadruple processing is performed.
For some bits of the port P5 and P6 direction registers correspond to pins used for two-phase pulse
input, set these bits for the input mode.
●
Normal processing
The timer up-counts the rising edges to the TAk
IN
pin when the phase has the relationship that the
TAk
IN
pin’s input signal level goes from “L” to “H” while the TAk
OUT
(k = 2 and 3) pin’s input signal
is “H” level.
The timer down-counts the falling edges to the TAk
IN
pin when the phase has the relationship that
the TAk
IN
pin’s input signal level goes from “H” to “L” while the TAk
OUT
pin’s input signal is “H” level.
(Refer to Figure 5.4.7.)
Fig. 5.4.6 Timer A2, A3, and A4 mode registers when two-phase pulse signal processing function is
selected
1 0 0 0 0 1
Timer A2 mode register (Address 58
16
)
Timer A3 mode register (Address 59
16
)
Timer A4 mode register (Address 5A
16
)
b7 b6 b5 b4 b3 b2 b1 b0
✕
: It may be either “0” or “1.”
✕ ✕
Fig. 5.4.7 Normal processing
TAk
OUT
TAk
IN
(k=2, 3)
“H”
“H”
“L”
Up
count
+1 +1 +1 –1 –1 –1
Down-
count
“L”
Up-
count
Up-
count
Up-
count
Down-
count
Down-
count