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ManualsBrandsMICROCHIP TECHNOLOGY ManualsMicrocontrollers, Microprocessors & QuartzesEmbedded microcontroller TQFP 44 (10x10) 8-Bit 20 MHz I/O number 32
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7
8272ES–AVR–04/2013
ATmega164A/PA/324A/PA/644A/PA/1284/P
2.2 Comparison between ATmega164A, ATmega164PA, ATmega324A, ATmega324PA,
ATmega644A, ATmega644PA, ATmega1284 and ATmega1284P
2.3 Pin Descriptions11
2.3.1 VCC
Digital supply voltage.
2.3.2 GND
Ground.
2.3.3 Port A (PA7:PA0)
Port A serves as analog inputs to the Analog-to-digital Converter.
Port A also serves as an 8-bit bi-directional I/O port with internal pull-up resistors (selected for
each bit). The Port A output buffers have symmetrical drive characteristics with both high sink
and source capability. As inputs, Port A pins that are externally pulled low will source current if
the pull-up resistors are activated. The Port A pins are tri-stated when a reset condition becomes
active, even if the clock is not running.
Port A also serves the functions of various special features of the Atmel
ATmega164A/164PA/324A/324PA/644A/644PA/1284/1284P as listed on page 80.
2.3.4 Port B (PB7:PB0)
Port B is an 8-bit bi-directional I/O port with internal pull-up resistors (selected for each bit). The
Port B output buffers have symmetrical drive characteristics with both high sink and source
capability. As inputs, Port B pins that are externally pulled low will source current if the pull-up
resistors are activated. The Port B pins are tri-stated when a reset condition becomes active,
even if the clock is not running.
Port B also serves the functions of various special features of the
ATmega164A/164PA/324A/324PA/644A/644PA/1284/1284P as listed on page 82.
2.3.5 Port C (PC7:PC0)
Port C is an 8-bit bi-directional I/O port with internal pull-up resistors (selected for each bit). The
Port C output buffers have symmetrical drive characteristics with both high sink and source
Table 2-1. Differences between ATmega164A, ATmega164PA, ATmega324A, ATmega324PA, ATmega644A,
ATmega644PA, ATmega1284 and ATmega1284P.
Device Flash EEPROM RAM Units
ATmega164A 16K 512 1K
bytes
ATmega164PA 16K 512 1K
ATmega324A 32K 1K 2K
ATmega324PA 32K 1K 2K
ATmega644A 64K 2K 4K
ATmega644PA 64K 2K 4K
ATmega1284 128K 4K 16K
ATmega1284P 128K 4K 16K