AT90CAN128
resistors are activated. The Port F pins are tri-stated when a reset condition becomes
active, even if the clock is not running.
Port F also serves the functions of the JTAG interface. If the JTAG interface is enabled,
the pull-up resistors on pins PF7(TDI), PF5(TMS), and PF4(TCK) will be activated even
if a reset occurs.
Port G (PG4..PG0)
Port G is a 5-bit I/O port with internal pull-up resistors (selected for each bit). The Port G
output buffers have symmetrical drive characteristics with both high sink and source
capability. As inputs, Port G pins that are externally pulled low will source current if the
pull-up resistors are activated. The Port G pins are tri-stated when a reset condition
becomes active, even if the clock is not running.
Port G also serves the functions of various special features of the AT90CAN128 as
listed on page 83.
RESET
Reset input. A low level on this pin for longer than the minimum pulse length will gener-
ate a reset. The minimum pulse length is given in caracteristics. Shorter pulses are not
guaranteed to generate a reset. The I/O ports of the AVR are immediately reset to their
initial state even if the clock is not running. The clock is needed to reset the rest of the
AT90CAN128.
XTAL1
XTAL2
AVCC
Input to the inverting Oscillator amplifier and input to the internal clock operating circuit.
Output from the inverting Oscillator amplifier.
AVCC is the supply voltage pin for the A/D Converter on Port F. It should be externally
connected to VCC, even if the ADC is not used. If the ADC is used, it should be con-
nected to VCC through a low-pass filter.
AREF
This 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.
7
4250E–CAN–12/04
ATMEL [ ATMEL ]
