Datasheet
22
AVRPLC16 v6
MikroElektronika
page
13.0. Input/output ports
Along the right side of the development system, there are four 10-pin connectors linked to the microcontroller I/O ports.
The microcontroller pins used for programming are not directly connected to the appropriate 10-pin connector, but via
the multiplexer. DIP switches SW1-SW4 enable each connector pin to be connected to one pull-up/pull-down resistor. It
depends on the position of jumpers J6-J9 whether the port pins are to be connected to pull-up or pull-down resistors.
Figure 13-4: Port PORTA connection schematic
)LJXUH J2 in pull-down
position
)LJXUH J2 in pull-up
position
)LJXUHI/O ports
Pull-up/pull-down resistors enable you to set the
logic level on all microcontroller input pins when
they are in idle state. The logic level depends on
the position of pull-up/pull-down jumpers. When
this jumper is placed in the pull-up position, the
input pins will be supplied with the 5V power
supply voltage. In other words, these pins will
be driven high (1). When this jumper is placed
in the pull-down position, the input pins will be
supplied with 0V, i.e. they will be fed with a logic
zero (0).
In order to feed some of the input pins with
desired logic level, it is necessary to enable
connection between that pin and resistor using
the appropriate DIP switch.
In Figure 13-4, the PORTA pins are driven low
(0). It means that jumper J6 is placed in the pull-
down position, whereas switches on the DIP
switch SW2 are set to the ON position.