M16C80 Datasheet, PDF (110/358 Pages) Renesas Technology Corp – RENESAS 16-BIT SINGLE-CHIP MICROCOMPUTER M16C FAMILY / M16C/80 SERIES

M16C/80 Group
13. Timer A
Table 13.3 Timer specifications in event counter mode
(when processing two-phase pulse signal with timers A2, A3, and A4)
Item
Specification
Count source
• Two-phase pulse signals input to TAiIN or TAiOUT pins (i=2 to 4)
Count operation
• 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
n : Set value
Count start condition
Count start flag is set (= 1)
Count stop condition
Count start flag is reset (= 0)
Interrupt request generation timing Timer overflows or underflows
TAiIN pin function
Two-phase pulse input (Set the corresponding function select registers A to I/
O port, and port direction register to "0")
TAiOUT pin function
Two-phase pulse input (Set the corresponding function select registers A to I/
O port, and port direction register to "0")
Read from timer
Count value can be read out by reading timer A2, A3, or A4 register
Write to timer
• When not counting
Value written to timer Ai register is written to both reload register and counter
• When counting
Value written to timer Ai register is written to only reload register
(Transferred to counter at next reload time)
Select function (Note 2) • Normal processing operation (TimerA2 and timer A3)
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
count count
Down
count
Down
count
• Multiply-by-4 processing operation (TimerA3 and timer A4)
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 up all edges
TAiIN
(i=3,4)
Count down all edges
Count up all edges Count down all edges
Note 1: This does not apply when the free-run function is selected.
Note 2: Timer A3 is selectable. Timer A2 is fixed to normal processing operation and timer A4 is fixed to
multiply-by-4 operation.
Rev.1.00 Aug. 02, 2005 ^{Page 99} of 329
REJ09B0187-0100