TIMER A
7.4 Event counter mode
7.4.4 Selectable functions
The following describes the selectable pulse output, and two-phase pulse signal processing functions.
(1) Pulse output function
The pulse output function is selected by setting the pulse output function select bit (bit 2 at addresses
5616 to 5A16, D616 to DA16) to “1.” When this function is selected, the TAiOUT pin is forcibly set for the
pulse output pin regardless of the corresponding bits of the port P6, port P2, and port P4 direction
registers. The TAiOUT pin outputs a pulse of which polarity is inverted each time a counter underflow
or overflow occurs. (Refer to Figure 7.3.5).
When the count start bit (addresses 4016, 4116) is “0” (count stopped), the TAiOUT pin outputs “L” level.
(2) Two-phase pulse signal processing function (Timers Aj)
For timer Aj (j = 2 to 4, 7 to 9), the two-phase pulse signal processing function is selected by setting
the timer Aj two-phase pulse signal processing select bits (bits 5 to 7 at addresses 4416 and C416
)
to “1.” (See Figure 7.4.5.) Figure 7.4.6 shows the timer Aj mode register when the two-phase pulse
signal processing function is selected.
For timers with two-phase pulse signal processing function selected, 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 timer Am (m = 2, 3, 7, 8), normal
processing is performed; in timer An (n = 4, 9), quadruple processing is performed.
For the port P6, port P2, and P4 direction registers’ bits corresponding to the pins used for two-phase
pulse input, be sure to set these bits for the input mode.
b7 b6 b5 b4 b3 b2 b1 b0
Timer A2 mode register (Address 5816
Timer A3 mode register (Address 5916
Timer A4 mode register (Address 5A16
)
)
)
0
1
0
0
0
1
ꢀ ꢀ
Timer A7 mode register (Address D816
Timer A8 mode register (Address D916
Timer A9 mode register (Address 5D16
)
)
)
X
: It may be either “0” or “1.”
Fig. 7.4.6 Timer Aj (j = 2 to 4, 7 to 9) mode register when two-phase pulse signal processing function
is selected
7905 Group User’s Manual Rev.1.0
7-26
RENESAS [ RENESAS TECHNOLOGY CORP ]
