ATMEGA168PA-PU Atmel, ATMEGA168PA-PU Datasheet - Page 54

• Manufacturer Part Number: ATMEGA168PA-PU
• Description: MCU, 8BIT, AVR, 16K FLASH, 28PDIP
• Manufacturer: Atmel

Specifications of ATMEGA168PA-PU

• Controller Family/series: Atmega
• No. Of I/o's: 23
• Eeprom Memory Size: 512Byte
• Ram Memory Size: 1KB
• Cpu Speed: 20MHz
• No.: RoHS Compliant
• Core Size: 8bit
• Program Memory Size: 16KB
• Oscillator Type: External, Internal
• Rohs Compliant: Yes

8271C–AVR–08/10
The following code example shows one assembly and one C function for changing the time-out
value of the Watchdog Timer.
Note:
Note: The Watchdog Timer should be reset before any change of the WDP bits, since a change
in the WDP bits can result in a time-out when switching to a shorter time-out period.
ATmega48A/48PA/88A/88PA/168A/168PA/328/328
Assembly Code Example
C Code Example
WDT_Prescaler_Change:
void WDT_Prescaler_Change(void)
{
}
; Turn off global interrupt
cli
; Reset Watchdog Timer
wdr
; Start timed sequence
lds r16, WDTCSR
ori
sts WDTCSR, r16
; --
; Set new prescaler(time-out) value = 64K cycles (~0.5 s)
ldi
sts WDTCSR, r16
; --
; Turn on global interrupt
sei
ret
__disable_interrupt();
__watchdog_reset();
/* Start timed
WDTCSR |= (1<<WDCE) | (1<<WDE);
/* Set new prescaler(time-out) value = 64K cycles (~0.5 s) */
WDTCSR
__enable_interrupt();
1.
See ”About Code Examples” on page 7.
r16, (1<<WDCE) | (1<<WDE)
Got four cycles to set the new values from here -
r16, (1<<WDE) | (1<<WDP2) | (1<<WDP0)
Finished setting new values, used 2 cycles -
= (1<<WDE) | (1<<WDP2) | (1<<WDP0);
(1)
(1)
sequence */
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