ATmega128(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
51. Shorter pulses are not guaranteed to generate a reset.
XTAL1
XTAL2
AVCC
Input to the inverting Oscillator amplifier and input to the internal clock operating circuit.
Output from the inverting Oscillator amplifier.
AVCC is the supply voltage pin for Port F and the A/D Converter. It should be externally con-
nected to VCC, even if the ADC is not used. If the ADC is used, it should be connected to VCC
through a low-pass filter.
AREF
PEN
AREF is the analog reference pin for the A/D Converter.
PEN is a programming enable pin for the SPI Serial Programming mode, and is internally pulled
high . By holding this pin low during a Power-on Reset, the device will enter the SPI Serial Pro-
gramming mode. PEN has no function during normal operation.
7
2467P–AVR–08/07
ATMEL [ ATMEL ]
