7906 datasheet(337/531 Pages) RENESAS

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WATCHDOG TIMER

7906 Group User’s Manual Rev.2.0

14-4

14.1 Block description

14.1.3 Particular function select register 2

When not using the watchdog timer, this register can be used to disable the watchdog timer. Figure 14.1.4

shows the structure of the particular function select register 2.

Fig. 14.1.4 Structure of particular function select register 2

In addition, even when the watchdog timer is disabled by this register, the watchdog timer can be active

only at the stop mode termination if the external clock input select bit (bit 1 at address 6216) = “0.” (Refer

to section “15.3 Stop mode.”)

Undefined

7 to 0

Bit

Function

At reset

R/W

Disables the watchdog timer.

When values of “7916” and “5016” succeedingly in this order, the watchdog timer will

stop its operation.

—

Particular function select register 2 (Address 6416)

Note: After reset, this register can be set only once. Writing to this register requires the following procedure:

• Write values of “7916” and “5016” to this register succeedingly in this order.

• For the above writing, be sure to use the MOVMB (MOVM when m = 1) instruction or the STAB (STA when m = 1).

Note that the following: if an interrupt occurs between writing of “7916” and next writing of “5016,” the watchdog timer does not

stop its operation.

If any of the following has been performed after reset, writing to this register is disabled from that time:

• If this register is read out.

• If writing to this register is performed by the procedure other than the above procedure.

7906 Datasheet(PDF) 337 Page - Renesas Technology Corp