ATMEGA32A_1 Datasheet, PDF (5/352 Pages) ATMEL Corporation – 8-bit Microcontroller with 32K Bytes In-System Programmable Flash

ATmega32A
2.2.4
2.2.5
2.2.6
2.2.7
2.2.8
2.2.9
metrical drive characteristics with both high sink and source capability. When pins PA0 to PA7
are used as inputs and are externally pulled low, they will source current if the internal 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 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 ATmega32A as listed on page
59.
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
capability. As inputs, Port C pins that are externally pulled low will source current if the pull-up
resistors are activated. The Port C pins are tri-stated when a reset condition becomes active,
even if the clock is not running. If the JTAG interface is enabled, the pull-up resistors on pins
PC5(TDI), PC3(TMS) and PC2(TCK) will be activated even if a reset occurs.
The TD0 pin is tri-stated unless TAP states that shift out data are entered.
Port C also serves the functions of the JTAG interface and other special features of the
ATmega32A as listed on page 62.
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 ATmega32A as listed on page
64.
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 27-1 on page
299. 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.
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