Renesas 7700 FAMILY User Manual page 110

[Precautions when operating in event counter mode]
1. By reading the timer Ai register, the counter value can be read out at any timing while counting is in
progress. However, when the timer Ai register is read at the reload timing shown in Figure 5.4.9, a value
"FFFF " (at the underflow) or "0000
16
after setting a value to the register while counting is not in progress and before the counter starts
counting, the set value is read out correctly.
(1) For down-count
Counter value
2
(Hex.)
Read value
2
(Hex.)
n = Reload register's contents
Fig. 5.4.9 Reading timer Ai register
2. The TAi pin is used for all functions listed below. Accordingly, only one of these functions can be
OUT
selected for each timer.
•Switching between up-count and down-count by TAi
•Pulse output function
•Two-phase pulse signal processing function for timers A2 to A4
" (at the overflow) is read out. When reading the timer Ai register
16
Reload
n
1 0 n – 1
1 0 FFFF n – 1
Time
7751 Group User's Manual
5.4 Event counter mode
(2) For up-count
Counter value
FFFD FFFE FFFF
(Hex.)
Read value
FFFD FFFE FFFF 0000 n + 1
(Hex.)
n = Reload register's contents
pin's input signal
OUT
TIMER A
Reload
n n + 1
Time
5–29