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2490R–AVR–02/2013
ATmega64(L)
RESET Reset input. A low level on this pin for longer than the minimum pulse length will generate a
reset, even if the clock is not running. The minimum pulse length is given in Table 19 on page
52. Shorter pulses are not guaranteed to generate a reset.
XTAL1 Input to the inverting Oscillator amplifier and input to the internal clock operating circuit.
XTAL2 Output from the inverting Oscillator amplifier.
AVCC AVCC is the supply voltage pin for Port F and the A/D Converter. It should be externally con-
nected to V
CC
, even if the ADC is not used. If the ADC is used, it should be connected to V
CC
through a low-pass filter.
AREF AREF is the analog reference pin for the A/D Converter.
PEN This is a programming enable pin for the SPI Serial Programming mode. By holding this pin low
during a Power-on Reset, the device will enter the SPI Serial Programming mode. PEN is inter-
nally pulled high. The pullup is shown in Figure 22 on page 52 and its value is given in Section
“DC Characteristics” on page 325. PEN
has no function during normal operation.
