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7470/7471/7477/7478 GROUP USER’S MANUAL

2-22

APPLICATION

2.3 Timers

7470

7471

7477

7478

2.3.3 Notes on use

2 When using a 16-bit counter by using two timers, take the following points into consideration

according to “1.12.5 Notes on use (2).”

qThe timing at which the timer value and the read value change, when two 8-bit timers are

connected in series, is shown in Figure 2.3.12, taking the case where timer 1 and timer 2 are

connected as an example (When Timer 1 and Timer 2 are connected and the set value of the

Timer 1 is 216 and the set value of the Timer 2 is 116).

The count source of timer 2 is the overflow signal of timer 1. In this case, the read value of timer

2 changes at the fall of the count source. When Timer 1 and Timer 2 are read continuously as

a 16-bit counter, the count source of timer 2 changes at the falling edge of the count source of

timer 1, so the A section can not be distinguished from the B section. Likewise, the C section

cannot be distinguished from the D section.

Fig. 2.3.12 Timing at which timer value and read value change in the case where two timers are

connected in series

2 For other notes on use, refer to “1.12 timers.”

,,,,

0FF

Writing to timer 1

Writing to timer 2

Timer 1 count source

Timer 1 value

Timer 1 read value

Timer 1 interrupt request

Timer 2 count source

Timer 2 value

Timer 2 read value

Timer 2 interrupt request

7477 Datasheet(PDF) 257 Page - Renesas Technology Corp