ATMEGA8HVD-4MX Atmel, ATMEGA8HVD-4MX Datasheet - Page 46

• Manufacturer Part Number: ATMEGA8HVD-4MX
• Description: MCU AVR 8K FLASH 2.1-8V 4MHZ QFN
• Manufacturer: Atmel
• Series: AVR® ATmegar

Specifications of ATMEGA8HVD-4MX

• Core Processor: AVR
• Core Size: 8-Bit
• Speed: 4MHz
• Peripherals: POR, WDT
• Number Of I /o: 5
• Program Memory Size: 8KB (4K x 16)
• Program Memory Type: FLASH
• Eeprom Size: 256 x 8
• Ram Size: 512 x 8
• Voltage - Supply (vcc/vdd): 2 V ~ 2.4 V
• Data Converters: A/D 1x10b
• Oscillator Type: Internal
• Operating Temperature: -20°C ~ 85°C
• Package / Case: 18-MLF® Exposed Pad (Staggered Leads), DFN
• For Use With: ATSTK600 - DEV KIT FOR AVR/AVR32ATSTK500 - PROGRAMMER AVR STARTER KIT
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Connectivity: -

46
ATmega4HVD/8HVD
1. In the same operation, write a logic one to the Watchdog change enable bit (WDCE)
2. Within the next four clock cycles, write the WDE and Watchdog prescaler bits (WDP)
The following code example shows one assembly and one C function for turning off the
Watchdog Timer. The example assumes that interrupts are controlled (e.g. by disabling inter-
rupts globally) so that no interrupts will occur during the execution of these functions.
Note:
Assembly Code Example
C Code Example
and WDE. A logic one must be written to WDE regardless of the previous value of the
WDE bit.
as desired, but with the WDCE bit cleared. This must be done in one operation.
WDT_off:
void WDT_off(void)
{
}
; Turn off global interrupt
cli
; Reset Watchdog Timer
wdr
; Clear WDRF in MCUSR
in
andi
out
; Write logical one to WDCE and WDE
; Keep old prescaler setting to prevent unintentional timeout
in
ori
out
; Turn off WDT
ldi
out
; Turn on global interrupt
sei
ret
__disable_interrupt();
__watchdog_reset();
/* Clear WDRF in MCUSR */
MCUSR &= ~(1<<WDRF);
/* Write logical one to WDCE and WDE */
/* Keep old prescaler setting to prevent unintentional timeout */
WDTCSR |= (1<<WDCE) | (1<<WDE);
/* Turn off WDT */
WDTCSR = 0x00;
__enable_interrupt();
1. See
r16, MCUSR
r16, (0xff & (0<<WDRF))
MCUSR, r16
r16, WDTCSR
r16, (1<<WDCE) | (1<<WDE)
WDTCSR, r16
r16, (0<<WDE)
WDTCSR, r16
”About Code Examples” on page
(1)
(1)
5.
8052B–AVR–09/08