Mitsubishi microcomputers
M16C / 61 Group
SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER
Timer A
Table 1.16.3. Timer specifications in event counter mode (when processing two-phase pulse
signal with timers A2, A3, and A4)
Item
Count source
Count operation
Specification
• Two-phase pulse signals input to TAiIN or TAiOUT pin
• Up count or down count can be selected by two-phase pulse signal
• When the timer overflows or underflows, the reload register content is
reloaded and the timer starts over again (Note)
Divide ratio
1/ (FFFF16 - n + 1) for up count
1/ (n + 1) for down count
Count start flag is set (= 1)
Count start flag is reset (= 0)
n : Set value
Count start condition
Count stop condition
Interrupt request generation timing Timer overflows or underflows
TAiIN pin function
TAiOUT pin function
Read from timer
Write to timer
Two-phase pulse input
Two-phase pulse input
Count value can be read out by reading timer A2, A3, or A4 register
• When counting stopped
When a value is written to timer A2, A3, or A4 register, it is written to both
reload register and counter
• When counting in progress
When a value is written to timer A2, A3, or A4 register, it is written to only
reload register. (Transferred to counter at next reload time.)
• Normal processing operation
Select function
The timer counts up rising edges or counts down falling edges on the TAiIN
pin when input signal on the TAiOUT pin is “H”
TAiOUT
TAiIN
(i=2,3)
Up
count
Up
count
Up
Down
Down
count
Down
count
count count
• Multiply-by-4 processing operation
If the phase relationship is such that the TAiIN pin goes “H” when the input
signal on the TAiOUT pin is “H”, the timer counts up rising and falling edges
on the TAiOUT and TAiIN pins. If the phase relationship is such that the
TAiIN pin goes “L” when the input signal on the TAiOUT pin is “H”, the timer
counts down rising and falling edges on the TAiOUT and TAiIN pins.
TAiOUT
Count down all edges
Count down all edges
Count up all edges
TAiIN
(i=3,4)
Count up all edges
Note: This does not apply when the free-run function is selected.
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MITSUBISHI [ Mitsubishi Group ]
