Datasheet

Alternate Functions of Port C on page 103
3.2.5. Port D (PD7..PD0)
Port D is an 8-bit bi-directional I/O port with internal pull-up resistors (selected for each bit). The Port D
output buffers have symmetrical drive characteristics with both high sink and source capability. As inputs,
Port D pins that are externally pulled low will source current if the pull-up resistors are activated. The Port
D pins are tri-stated when a reset condition becomes active, even if the clock is not running.
Port D also serves the functions of various special features of the Atmel ATmega16M1/32M1/64M1 as
listed in Alternate Functions of Port D. Refer to Alternate Functions of Port D for details.
Related Links
Alternate Functions of Port D on page 107
3.2.6. Port E (PE2..0) RESET/ XTAL1/XTAL2
Port E is an 3-bit bi-directional I/O port with internal pull-up resistors (selected for each bit). The Port E
output buffers have symmetrical drive characteristics with both high sink and source capability. As inputs,
Port E pins that are externally pulled low will source current if the pull-up resistors are activated. The Port
E pins are tri-stated when a reset condition becomes active, even if the clock is not running.
If the RSTDISBL Fuse is programmed, PE0 is used as an I/O pin. Note that the electrical characteristics
of PE0 differ from those of the other pins of Port E.
If the RSTDISBL Fuse is unprogrammed, PE0 is used as a 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 System and reset characteristics. Shorter pulses are not guaranteed to generate a
Reset.
Depending on the clock selection fuse settings, PE1 can be used as input to the inverting Oscillator
amplifier and input to the internal clock operating circuit.
Depending on the clock selection fuse settings, PE2 can be used as output from the inverting Oscillator
amplifier.
The various special features of Port E are elaborated in Alternate Functions of Port E.
Related Links
CPU Clock – clkCPU on page 47
I/O Clock – clkI/O on page 48
Flash Clock – clkFLASH on page 48
Asynchronous Timer Clock – clkASY on page 48
ADC Clock – clkADC on page 48
Alternate Functions of Port E on page 110
3.2.7. AV
CC
AV
CC
is the supply voltage pin for the A/D Converter, D/A Converter, Current source. It should be
externally connected to V
CC
, even if the ADC, DAC are not used. If the ADC is used, it should be
connected to V
CC
through a low-pass filter.
3.2.8. AREF
This is the analog reference pin for the A/D Converter.
Atmel ATmega16M1/32M1/64M1 [DATASHEET]
Atmel-8209F-ATmega16M1/32M1/64M1_Datasheet_Complete-10/2016
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