Atmel ATA6264 - Manual (Page 47)

47
4929B–AUTO–01/07
ATA6264 [Preliminary]
16. Watchdog Function
To verify the proper function of the microcontroller, watchdog logic is included. As the ATA6264
is powered up, the RESQ2 signal stays low until the first valid watchdog trigger is detected.
Features:
• Watchdog trigger has to be done via the serial interface
• In case of a watchdog-trigger mismatch, the ATA6264 is set into its default state (latches,
MISO status, etc.) and RESQ is set to low.
• Watchdog has to be triggered cyclically (prescaler for repetition time is set via serial interface
command). Default: 16-ms repetition time
Figure 16-1. Watchdog Trigger Functional Principle
Re-configure prescaler during
1 st and 2nd trigger watchdog
command
Serial
interface
communication
chip
internal
trigger
window
VCORE
4.8V
5.0V
16 ms
16 ms WD cyc* WD cyc*
4 ms 4 ms
RESQ
t
t
t
t
an
y diff
erent
SPI CMD
re-configure
prescaler
T
rg Wdg
CMD
T
rg Wdg
CMD
T
rg Wdg
CMD
* Watchdog cycle, see pages 48 and 49