M I K R O E L E K T R O N I K A S O F T W A R E A N D H A R D W A R E S O L U T I O N S F O R T H E E M B E D D E D W O R L D
EasyAVR
USB
4
EasyAVR4 User
’
s Manual
MikroElektronika
Development
tools
1
18
8
page
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IITT
CC
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EE
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On Fig. 20 the J1 jumper is set
to pull-up, therefore when the
button is not pressed, pull-up
resistor pulls the microcon-
troller’s PA3 pin to +5V.
A button press causes the port
pin to be connected to ground
(J6 is in the lower position).
Thus, only when the button is
pressed the microcontroller
will sense a logical zero; other-
wise the pin state will always
be logical one.
On Fig. 21 the J6 jumper is set
to pull-down, therefore when
the button is not pressed, pull-
down resistor pulls the micro-
controller’s PA3 pin to 0V.
A button press causes the port
pin to be connected to +5V (J6
is in the higher position).
Thus, only when the button is
pressed the microcontroller
will sense a logical one; other-
wise the pin state will always
be logical zero.
A
TMEGA
PB1
PB2
PB3
PB4
PB5
PB6
PB7
RST
VCC
PC7
AVCC
PA7
PA6
PA5
PA4
PA3
PA2
PA0
PA1
GND
XT2
PB0
AREF
AGND
PA3
PORTA
pull-up
0V while pressed
vcc
J1
1
ON
8
7
6
5
4
3
2
SW1
vcc
J6
VCC
A
TMEGA
PB1
PB2
PB3
PB4
PB5
PB6
PB7
RST
VCC
PC7
AVCC
PA7
PA6
PA5
PA4
PA3
PA2
PA0
PA1
GND
XT2
PB0
AREF
AGND
PA3
PORTA
pull-down
5V while pressed
vcc
vcc
J1
1
ON
8
7
6
5
4
3
2
SW1
J6
VCC
Figure 20.
Figure 21.
Button with pull-up resistor
Button with pull-down resistor
