ATMEGA329P-20MN Atmel, ATMEGA329P-20MN Datasheet - Page 51

• Manufacturer Part Number: ATMEGA329P-20MN
• Description: IC MCU AVR 32K 20MHZ 64QFN
• Manufacturer: Atmel
• Series: AVR® ATmegar

Specifications of ATMEGA329P-20MN

• Core Processor: AVR
• Core Size: 8-Bit
• Speed: 20MHz
• Connectivity: SPI, UART/USART, USI
• Peripherals: Brown-out Detect/Reset, LCD, POR, PWM, WDT
• Number Of I /o: 54
• Program Memory Size: 32KB (16K x 16)
• Program Memory Type: FLASH
• Eeprom Size: 1K x 8
• Ram Size: 2K x 8
• Voltage - Supply (vcc/vdd): 2.7 V ~ 5.5 V
• Data Converters: A/D 8x10b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 64-MLF®, 64-QFN
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

8021G–AVR–03/11
• Bit 3 – WDE: Watchdog Enable
When the WDE is written to logic one, the Watchdog Timer is enabled, and if the WDE is written
to logic zero, the Watchdog Timer function is disabled. WDE can only be cleared if the WDCE bit
has logic level one. To disable an enabled Watchdog Timer, the following procedure must be
followed:
1. In the same operation, write a logic one to WDCE and WDE. A logic one must be written
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.
page
• 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 Time-out Periods
are shown in
Table 10-2.
WDP2
to WDE even though it is set to one before the disable operation starts.
0
0
0
0
1
1
1
1
49.
WDP1
Table 10-2 on page
0
0
1
1
0
0
1
1
Watchdog Timer Prescale Select
”Timed Sequences for Changing the Configuration of the Watchdog Timer” on
WDP0
0
1
0
1
0
1
0
1
Oscillator Cycles
Number of WDT
51.
1,024K cycles
2,048K cycles
128K cycles
256K cycles
512K cycles
16K cycles
32K cycles
64K cycles
Typical Time-out at
ATmega329P/3290P
V
CC
17.1ms
34.3ms
68.5ms
0.14s
0.27s
0.55s
1.1s
2.2s
= 3.0V
Typical Time-out at
V
CC
16.3ms
32.5ms
65ms
0.13s
0.26s
0.52
1.0s
2.1s
= 5.0V
51