ata6616 ATMEL Corporation, ata6616 Datasheet - Page 80

• Manufacturer Part Number: ata6616
• Description: Microcontroller With Lin Transceiver, 5v Regulator And Watchdog
• Manufacturer: ATMEL Corporation

4.7.3.2
80
ATA6616/ATA6617 [Preliminary]
Clock monitoring
The following code example shows one assembly and one C function for changing the time-out
value of the Watchdog Timer.
The Watchdog Timer can be used to detect a loss of system clock. This configuration is driven
by the dynamic clock switch circuit. Please refer to
60
Assembly Code Example
C Code Example
Notes:
for more information.
WDT_Prescaler_Change:
void WDT_Prescaler_Change(void)
{
}
; Turn off global interrupt
cli
; Reset Watchdog Timer
wdr
; Start timed sequence
lds r16, WDTCR
ori
sts WDTCR, r16
; -- Got four cycles to set the new values from here -
; Set new prescaler(time-out) value = 64K cycles (~0.5 s)
ldi
sts WDTCR, r16
; -- Finished setting new values, used 2 cycles -
; Turn on global interrupt
sei
ret
__disable_interrupt();
__watchdog_reset();
/* Start timed sequence */
WDTCR |= (1<<WDCE) | (1<<WDE);
/* Set new prescaler(time-out) value = 64K cycles (~0.5 s) */
WDTCR
__enable_interrupt();
1. See
2. 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.
r16, (1<<WDCE) | (1<<WDE)
r16, (1<<WDE) | (1<<WDP2) | (1<<WDP0)
= (1<<WDE) | (1<<WDP2) | (1<<WDP0);
Section 4.2.6 “About Code Examples” on page 31
(1)
(1)
DRAFT
Section 4.5.3.8 “Clock Monitoring” on page
9132A–AUTO–10/08