Rainbow Electronics ATmega32L - Manual (Page 5)

5
ATmega32(L)
2503C–AVR–10/02
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 ATmega32 as listed
on page 55.
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 acti-
vated 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
ATmega32 as listed on page 58.
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 ATmega32 as listed
on page 60.
RESET Reset Input. A low level on this pin for longer than the minimum pulse length will gener-
ate a reset, even if the clock is not running. The minimum pulse length is given in Table
15 on page 35. 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.
AVCC AVCC is the supply voltage pin for Port A and the A/D Converter. It should be externally
connected to V
CC
, even if the ADC is not used. If the ADC is used, it should be con-
nected to V
CC
through a low-pass filter.
AREF AREF is the analog reference pin for the A/D Converter.
About Code
Examples
This documentation contains simple code examples that briefly show how to use various
parts of the device. These code examples assume that the part specific header file is
included before compilation. Be aware that not all C Compiler vendors include bit defini-
tions in the header files and interrupt handling in C is compiler dependent. Please
confirm with the C Compiler documentation for more details.