MC-78F0712-KIT Renesas Electronics America, MC-78F0712-KIT Datasheet - Page 177

• Manufacturer Part Number: MC-78F0712-KIT
• Description: KIT REF SYSTEM 78K0 UPD78F0712
• Manufacturer: Renesas Electronics America

Specifications of MC-78F0712-KIT

• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

9.4
9.4.1
the watchdog timer mode register (WDTM) = 1, 1, 1). The watchdog timer operation cannot be stopped.
The operation clock of watchdog timer is fixed to the internal low-speed oscillation clock.
After reset is released, operation is started at the maximum cycle (bits 2, 1, and 0 (WDCS2, WDCS1, WDCS0) of
The following shows the watchdog timer operation after reset release.
1.
2.
3.
Notes 1.
Caution In this mode, operation of the watchdog timer absolutely cannot be stopped even during STOP
Operation of Watchdog Timer
The status after reset release is as follows.
The following should be set in the watchdog timer mode register (WDTM) by an 8-bit memory manipulation
instruction
After the above procedures are executed, writing ACH to WDTE clears the count to 0, enabling recounting.
Watchdog timer operation when “Internal low-speed oscillator cannot be stopped” is selected by
option byte
Operation clock: Internal low-speed oscillation clock
Cycle: f
Counting starts
Cycle: Set using bits 2 to 0 (WDCS2 to WDCS0)
2.
instruction execution. For 8-bit timer 51 (TM51), a division of the internal low-speed oscillation
clock can be selected as the count source, so clear the watchdog timer using the interrupt
request of TM51 before the watchdog timer overflows after STOP instruction execution. If this
processing is not performed, an internal reset signal is generated when the watchdog timer
overflows after STOP instruction execution.
The operation clock (internal low-speed oscillation clock) cannot be changed. If any value is written to
bits 3 and 4 (WDCS3, WDCS4) of WDTM, it is ignored.
As soon as WDTM is written, the counter of the watchdog timer is cleared.
Notes 1, 2
RL
/2
18
.
(1.09 seconds: At operation with f
CHAPTER 9 WATCHDOG TIMER
User’s Manual U17890EJ2V0UD
RL
= 240 kHz (TYP.))
175