Datasheet

M16C/6S Group Timer A

R01DS0201EJ0502 Rev.5.02 page 83 of 203

Dec 25, 2012

Item Specification

Count source • External signals input to TAiIN pin (i=0 to 4) (effective edge can be selected

in program)

timer Aj (j=i-1, except j=4 if i=0) overflows or underflows,

timer Ak (k=i+1, except k=0 if i=4) overflows or underflows

Count operation • Up-count or down-count can be selected by external signal or program

• When the timer overflows or underflows, it reloads the reload register con-

tents and continues counting. When operating in free-running mode, the

timer continues counting without reloading.

Divided ratio 1/ (FFFF16 - n + 1) for up-count

1/ (n + 1) for down-count n : set value of TAi register 000016 to FFFF16

Count start condition Set TAiS bit of TABSR register to “1” (= start counting)

Count stop condition Set TAiS bit to “0” (= stop counting)

Interrupt request generation timing

Timer overflow or underflow

TAiIN pin function I/O port or count source input i≠2, 3

TAiOUT pin function I/O port, pulse output, or up/down-count select input

Read from timer Count value can be read by reading TAi register

Write to timer

• When not counting and until the 1st count source is input after counting start

Value written to TAi register is written to both reload register and counter

• When counting (after 1st count source input)

Value written to TAi register is written to only reload register

(Transferred to counter when reloaded next)

Select function • Free-run count function

Even when the timer overflows or underflows, the reload register content is

not reloaded to it

• Pulse output function

Whenever the timer underflows or underflows, the output polarity of TAiOUT

pin is inverted . When not counting, the pin outputs a low.

2. Event Counter Mode

In event counter mode, the timer counts pulses from an external device or overflows and underflows of

other timers. Timer A4 can count two-phase external signals. Table 1.12.2 lists specifications in event

counter mode (when not processing two-phase pulse signal). Table 1.12.3 lists specifications in event

counter mode (when processing two-phase pulse signal with the timer A4). Figure 1.12.7 shows TAiMR

TA4MR registers in event counter mode (when processing two-phase pulse signal with the timer A4).

Table 1.12.2. Specifications in Event Counter Mode (when not processing two-phase pulse signal)