M16C62_M Datasheet, PDF (352/615 Pages) Renesas Technology Corp – 16-BIT SINGLE-CHIP MICROCOMPUTER M16C FAMILY / M16C/60 SERIES

Timer A
Mitsubishi microcomputers
M16C / 62A Group
SINGLE-CHIP 16-BIT CMOS MICROCOMPUTER
2.2.14 Precautions for Timer A (event counter mode)
(1) To clear reset, the count start flag is set to “0”. Set a value in the timer Ai register, then set the
flag to “1”.
(2) Reading the timer Ai register while a count is in progress allows reading, with arbitrary timing,
the value of the counter. Reading the timer Ai register with the reload timing shown in Figure
2.2.29 gets “FFFF16” by underflow or “000016” by overflow. Reading the timer Ai register after
setting a value in the timer Ai register with a count halted but before the counter starts count-
ing gets a proper value.
(3) Please note the standards for the differences between the 2 pulses used in the 2-phase pulse
signals input signals to the TAiIN pin and TAiOUT pin (i = 2, 3, 4), as shown in Figure 2.2.30.
(4) When free run type is selected, if count is stopped, set a value in the timer Ai register again.
(1) Down count
Reload
(2) Up count
Reload
Counter value
(Hex.)
2 1 0 n n–1
Read value
(Hex.)
2 1 0 FFFF ^{n – 1}
n = reload register content
Time
Counter value
(Hex.)
FFFD FFFE FFFF n n + 1
Read value
(Hex.)
FFFD FFFE FFFF 0000 n + 1
n = reload register content
Time
Figure 2.2.29. Reading timer Ai register
TA2IN
TA3IN
TA4IN
TA2OUT
TA3OUT
TA4OUT
T1
T2 T3
Figure 2.2.30. Standard of 2-phase pulses
Vcc = 5V, f(XIN) = 16MHz
T1
(Min.)
T2, T3
(Min.)
800ns
200ns
Vcc = 3V, f(XIN) = 10MHz, one-wait
T1
(Min.)
T2, T3
(Min.)
2µs
500ns
2-35