External reset, Watchdog reset, Atmega161(l) – Rainbow Electronics ATmega161L User Manual
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ATmega161(L)
1228C–AVR–08/02
External Reset
An External Reset is generated by a low level on the RESET pin. Reset pulses longer
than 500 ns will generate a Reset, even if the clock is not running. Shorter pulses are
not guaranteed to generate a Reset. When the applied signal reaches the Reset
Threshold Voltage (V
RST
) on its positive edge, the delay timer starts the MCU after the
Time-out period (t
TOUT
) has expired.
Figure 27. External Reset during Operation
Watchdog Reset
When the Watchdog times out, it will generate a short reset pulse of 1 XTAL cycle dura-
tion. On the falling edge of this pulse, the delay timer starts counting the Time-out period
(t
TOUT
). Refer to page 58 for details on operation of the Watchdog.
Figure 28. Watchdog Reset during Operation