WATCHDOG TIMER
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.
b7
b0
Particular function select register 2 (Address 6416
)
Bit
Function
At reset
R/W
Disables the watchdog timer.
When values of “7916” and “5016” succeedingly in this order, the watchdog timer will
7 to 0
—
Undefined
stop its operation.
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.
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.”)
7906 Group User’s Manual Rev.2.0
14-4
RENESAS [ RENESAS TECHNOLOGY CORP ]
