7733 datasheet(138/940 Pages) RENESAS

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TIMER A

7733 Group User’s Manual

6–27

6.4.3 Selectable functions

The free-run count, pulse output, and two-phase pulse signal processing functions are described below.

(1) Free-run count function (Timers A2 to A4)

For timers A2 to A4, when the count type selection bit (bit 6 at addresses 5816 to 5A16) is set to “1,”

the free-run count function is selected. When the free-run count function is selected, although a timer

A2/A3/A4 interrupt request is generated at an overflow or underflow, the reload register’s contents is

not reloaded into the counter.

Figure 6.4.7 shows an operation example when the free-run count function is selected.

6.4 Event counter mode

Fig. 6.4.7 Operation example when free-run count function is selected (without pulse output function

and two-phase pulse signal processing function)

FFFF16

000016

Time

Count start

flag

Timer A2/A3/A4

interrupt request

bit

“1”

n = Reload register’s contents

Cleared to “0” when an interrupt request is accepted; otherwise, cleared by software

Set to “1” by software

Counting is started.

Up-down flag “1”

“0”

g The above is applied when the up-down flag’s contents is selected as the up-down switching factor

(i.e., up-down switching factor selection bit = “0”).

Set to “1” by software

After an underflow, counter starts counting from FFFF16.

After an overflow, counter starts counting from 000016.

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