TIMER A
[Precautions for event counter mode]
[Precautions for event counter mode]
1. While counting is in progress, by reading the timer Ai (i = 0 to 9) register, the counter value can be read
out at any timing. However, if the timer Ai register is read at the reload timing shown in Figure 7.4.9,
the value “FFFF16” (at an underflow) or “000016” (at the overflow) is read out. If reading is performed in
the period from when a value is set into the timer Ai register with the counter stopped until the counter
starts counting, the set value is correctly read out.
(1) For countdown
(2) For countup
Reload
Reload
Counter value
(Hex.)
Counter value
(Hex.)
n
2
2
1
1
0
0
n – 1
n
n + 1
FFFE FFFF
FFFD
Read value
(Hex.)
Read value
(Hex.)
n – 1
n + 1
FFFD FFFE FFFF
0000
FFFF
Time
Time
n : reload register’s contents
n : reload register’s contents
Fig. 7.4.9 Reading timer Ai register
2. The TAiOUT pin is used for all functions listed below. Accordingly, only one of these functions can be
selected for each timer.
ꢀ Switching between countup and countdown by TAiOUT pin’s input signal
ꢀ Pulse output function
ꢀ Two-phase pulse signal processing function (Timers A2 to A4, A7 to A9)
7905 Group User’s Manual Rev.1.0
7-28
RENESAS [ RENESAS TECHNOLOGY CORP ]
