ATMEGA162_1 Datasheet, PDF (54/324 Pages) ATMEL Corporation – 8-bit Microcontroller with 16K Bytes In-System Programmable Flash

1. In the same operation, write a logic one to WDCE and WDE. A logic one must be written
to WDE even though it is set to one before the disable operation starts.
2. Within the next four clock cycles, write a logic 0 to WDE. This disables the Watchdog.
In safety level 2, it is not possible to disable the Watchdog Timer, even with the algorithm
described above. See “Timed Sequences for Changing the Configuration of the Watchdog
Timer” on page 56.
• Bits 2..0 – WDP2, WDP1, WDP0: Watchdog Timer Prescaler 2, 1, and 0
The WDP2, WDP1, and WDP0 bits determine the Watchdog Timer prescaling when the Watch-
dog Timer is enabled. The different prescaling values and their corresponding Timeout Periods
are shown in Table 23.
Table 23. Watchdog Timer Prescale Select
WDP2 WDP1 WDP0
Number of WDT
Oscillator Cycles
0
0
0
16K (16,384)
0
0
1
32K (32,768)
0
1
0
65K (65,536)
0
1
1
128K (131,072)
1
0
0
256K (262,144)
1
0
1
512K (524,288)
1
1
0
1,024K (1,048,576)
1
1
1
2,048K (2,097,152)
Typical Time-out
at V_CC = 3.0V
17 ms
34 ms
69 ms
0.14 s
0.27 s
0.55 s
1.1 s
2.2 s
Typical Time-out
at V_CC = 5.0V
16 ms
33 ms
65 ms
0.13 s
0.26 s
0.52 s
1.0 s
2.1 s
54 ATmega162/V
2513K–AVR–07/09