Fujitsu FR81S User Manual
CHAPTER 18: WATCHDOG TIMER
4. Registers
FUJITSU SEMICONDUCTOR LIMITED
CHAPTER : WATCHDOG TIMER
FUJITSU SEMICONDUCTOR CONFIDENTIAL
9
4.1. Watchdog Control Register 0 : WDTCR0 (WatchDog
Timer Configuration Register 0)
The bit configuration of the watchdog control register 0 is shown.
This register configures each of the settings of the watchdog timer 0.
Writing to this register is invalid after the watchdog timer 0 is activated.
WDTCR0 : Address 003C
H
(Access: Byte, Half-word, Word)
bit7
bit6
bit5
bit4
bit3
bit2
bit1
bit0
Reserved RSTP
Reserved
WT[3:0]
Initial value
0
0
0
0
0
0
0
0
Attribute R0,W0
R/W
R0,W0
R0,W0
R/W
R/W
R/W
R/W
[bit7] Reserved: (Reserved bit)
Be sure to write "0" to this bit. The read value is "0".
[bit6] RSTP (Reset by SToP) : Stop mode detection reset enable
This bit configures whether a reset signal is generated or not when a transition to watch mode or stop mode
is detected while the watchdog timer 0 is operating. When this bit is enabled, the watchdog timer reset 0
occurs when the CPU switches to watch mode or stop mode. When this bit is not enabled, the watchdog
timer 0 is paused when the CPU switches to watch mode or stop mode, and the count stops until the CPU
recovers from watch mode or stop mode.
RSTP
Stop mode detection
0
Not detected (initial value)
1
Generates a reset signal when detected
Writing to this bit after the watchdog timer 0 is activated is invalid.
[bit5, bit4] Reserved: (Reserved bits)
Be sure to write "0" to these bits. The read value is "0".
[bit3 to bit0] WT[3:0] (Watchdog Timer interval) : Watchdog timer cycle selection
These bits configure the number of cycles of timer interval starting from when the watchdog timer 0 was
last cleared to when a watchdog reset 0 is issued. Details are shown as follows.
WT[3:0]
The Watchdog Timer 0 cycle
0000
PCLK (Peripheral Clock) × 2
9
cycles
0001
PCLK × 2
10
cycles
0010
PCLK × 2
11
cycles
0011
PCLK × 2
12
cycles
0100
PCLK × 2
13
cycles
0101
PCLK × 2
14
cycles
0110
PCLK × 2
15
cycles
0111
PCLK × 2
16
cycles
1000
PCLK × 2
17
cycles
MB91520 Series
MN705-00010-1v0-E
618