Datasheet

49
8018P–AVR–08/10
ATmega169P
Figure 10-3. MCU Start-up, RESET Extended Externally
10.2.2 External Reset
An External Reset is generated by a low level on the RESET
pin. Reset pulses longer than the
minimum pulse width (see ”System and Reset Characteristics” on page 333) 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 counter starts the MCU after the Time-out period – t
TOUT
– has expired.
Figure 10-4. External Reset During Operation
RESET
TIME-OUT
INTERNAL
RESET
t
TOUT
V
POT
V
RST
V
CC
CC