ATMEGA8HVD-4MX Atmel, ATMEGA8HVD-4MX Datasheet - Page 47

• 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: -

8052B–AVR–09/08
Note: If the Watchdog is accidentally enabled, for example by a runaway pointer or Black-out
condition, the device will be reset and the Watchdog Timer will stay enabled. If the code is not
set up to handle the Watchdog, this might lead to an eternal loop of timeout resets. To avoid
this situation, the application software should always clear the Watchdog System Reset Flag
(WDRF) and the WDE control bit in the initialisation routine, even if the Watchdog is not in use.
The following code example shows one assembly and one C function for changing the timeout
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 timeout when switching to a shorter timeout period.
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
in
ori
out
; --
; Set new prescaler(timeout) value = 64K cycles (~0.5 s)
ldi
out
; --
; Turn on global interrupt
sei
ret
__disable_interrupt();
__watchdog_reset();
/* Start timed
WDTCSR |= (1<<WDCE) | (1<<WDE);
/* Set new prescaler(timeout) value = 64K cycles (~0.5 s) */
WDTCSR
__enable_interrupt();
1. See
r16, WDTCSR
r16, (1<<WDCE) | (1<<WDE)
WDTCSR, r16
Got four cycles to set the new values from here -
r16, (1<<WDE) | (1<<WDP2) | (1<<WDP0)
WDTCSR, r16
Finished setting new values, used 2 cycles -
”About Code Examples” on page
= (1<<WDE) | (1<<WDP2) | (1<<WDP0);
(1)
(1)
equence */
5.
ATmega4HVD/8HVD
47