Timers (Timer A)
113
Mitsubishi microcomputers
M16C / 62P Group
SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER
development
Preliminary Specifications Rev.1.0
Specifications in this manual are tentative and subject to change.
Item
Specification
Count source
External signals input to TAi
IN
pin (i=0 to 4) (effective edge can be selected
in program)
Timer B2 overflows or underflows,
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
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.
1/ (FFFF
16
- n + 1) for up-count
1/ (n + 1) for down-count n : set value of TAi register 0000
16
to FFFF
16
Set TAiS bit of TABSR register to “1” (= start counting)
Set TAiS bit to “0” (= stop counting)
Interrupt request generation timing
Timer overflow or underflow
TAi
IN
pin function
I/O port or count source input
TAi
OUT
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 TAi
OUT
pin is inverted . When not counting, the pin outputs a low.
Count operation
Divided ratio
Count start condition
Count stop condition
2. Event Counter Mode
In event counter mode, the timer counts pulses from an external device or overflows and underflows of
other timers. Timers A2, A3 and A4 can count two-phase external signals. Table 1.14.2 lists specifica-
tions in event counter mode (when not processing two-phase pulse signal). Table 1.14.3 lists specifica-
tions in event counter mode (when processing two-phase pulse signal with the timers A2, A3 and A4).
Figure 1.14.8 shows TAiMR register in event counter mode (when not processing two-phase pulse sig-
nal). Figure 1.14.9 shows TA2MR to TA4MR registers in event counter mode (when processing two-
phase pulse signal with the timers A2, A3 and A4).
Table 1.14.2. Specifications in Event Counter Mode (when not processing two-phase pulse signal)