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 5816, 5A16, DA16) to “1.” When this function is selected, the TAjOUT pin is forcibly set for the
pulse output pin regardless of the corresponding bits of the port P2 and port P6 direction registers.
The TAjOUT 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 TAjOUT pin outputs “L” level.
(2) Two-phase pulse signal processing function (Timers A2, A4, A9)
For timers A2, A4, A9, the two-phase pulse signal processing function is selected by setting the two-
phase pulse signal processing select bits (bits 5 and 7 at address 4416, bit 7 at address C416) to “1.”
(See Figure 7.4.5.) Figure 7.4.6 shows the timer A2/A4/A9 mode registers 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 A2, normal processing is performed;
in timers A4 and A9, quadruple processing is performed.
For the port P2 and P6 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 A4 mode register (Address 5A16
Timer A9 mode register (Address 5D16
)
)
)
0
1
0
0
0
1
ꢀ ꢀ
ꢀꢀ: It may be either “0” or “1.”
Fig. 7.4.6 Timer A2/A4/A9 mode registers when two-phase pulse signal processing function is selected
7906 Group User’s Manual Rev.2.0
7-26
RENESAS [ RENESAS TECHNOLOGY CORP ]
