This is an 8-bit, bi-directional I/O port with internal pull-up resistors, individually selectable for each bit.
The output buffers have symmetrical drive characteristics, with both high sink and source capability. As
inputs, the port pins that are externally pulled low will source current if pull-up resistors are activated. Port
pins are tri-stated when a reset condition becomes active, even if the clock is not running.
5.2.4. Port B (PB[7:0])
This is an 8-bit, bi-directional I/O port with internal pull-up resistors, individually selectable for each bit.
The output buffers have symmetrical drive characteristics, with both high sink and source capability. As
inputs, the port pins that are externally pulled low will source current if pull-up resistors are activated. Port
pins are tri-stated when a reset condition becomes active, even if the clock is not running.
This port also serves the functions of various special features.
5.2.5. Port C (PC[7:0])
This is an 8-bit, bi-directional I/O port with internal pull-up resistors, individually selectable for each bit.
The output buffers have symmetrical drive characteristics, with both high sink and source capability. As
inputs, the port pins that are externally pulled low will source current if pull-up resistors are activated. Port
pins are tri-stated when a reset condition becomes active, even if the clock is not running.
This port also serves the functions of the JTAG interface, along with special features.
5.2.6. Port D (PD[7:0])
This is an 8-bit, bi-directional I/O port with internal pull-up resistors, individually selectable for each bit.
The output buffers have symmetrical drive characteristics, with both high sink and source capability. As
inputs, the port pins that are externally pulled low will source current if pull-up resistors are activated. Port
pins are tri-stated when a reset condition becomes active, even if the clock is not running.
This port also serves the functions of various special features.
5.2.7. 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. Shorter pulses are not guaranteed to generate a reset.
5.2.8. XTAL1
Input to the inverting Oscillator amplifier and input to the internal clock operating circuit.
5.2.9. XTAL2
Output from the inverting Oscillator amplifier.
5.2.10. AVCC
AVCC is the supply voltage pin for Port A and the Analog-to-digital Converter. It should be externally
connected 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.
5.2.11. AREF
This is the analog reference pin for the Analog-to-digital Converter.
Atmel ATmega164P/V [DATASHEET]
Atmel-42742B-ATmega164P/V_Datasheet_Summary-08/2016
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