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
ATmega32 as listed on page 60.
Zitat:
• TDI – Port C, Bit 5
TDI, JTAG Test Data In: Serial input data to be shifted in to the
Instruction Register or Data Register
(scan chains). When the JTAG interface is enabled, this pin can not be
used as an I/O pin.
• TDO – Port C, Bit 4
TDO, JTAG Test Data Out: Serial output data from Instruction Register or
Data Register. When
the JTAG interface is enabled, this pin can not be used as an I/O pin.
The TD0 pin is tri-stated unless TAP states that shifts out data are
entered.
• TMS – Port C, Bit 3
TMS, JTAG Test Mode Select: This pin is used for navigating through the
TAP-controller state
machine. When the JTAG interface is enabled, this pin can not be used as
an I/O pin.
• TCK – Port C, Bit 2
TCK, JTAG Test Clock: JTAG operation is synchronous to TCK. When the
JTAG interface is
enabled, this pin can not be used as an I/O pin.
Mit der AVR Debug Funktion sieht man aber (fälschlich) das alles geht
und die Pins richtig geschaltet werden.
Das stimmt aber nicht.