mikroElektronika EasyARM v6, Руководство пользователя

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20
EasyARM v6
MikroElektronika
page
3.3V
0V
VCC-3.3
J2
P0.14
RN2 8x10K
R27
220
VCC-3.3
J17
J16 P0.14
up
pull
down
LPC2148
P1.27
P0.31
GND P0.
0
P1.31 P0.
1
P0.
2
VCC3 P1.26 GND P0.
3
P0.
4
P1.25 P0.
5
P0.
6
P0.
7
P1.24
VREF XT
AL1
XT
AL2
P1.28 GNDA P0.23 RESET P1.29 P0.20 P0.19 P0.18 P1.30 VCC3
GND VBA
T
P0.21 P1.20
P0.17
P0.16
P0.15
P1.21
VCC3
GND
P0.14
P1.22
P0.13
P0.12
P0.11
P1.23
P0.10
P0.9
P0.8
P0.22
RTXC1
P1.19
RTXC2
GND
VCCA
P1.18
P0.25
D+
D-
P1.17
P0.28
P0.29
P0.30
P1.16
VCC3
Pull-up/pull-down resistors enable you to feed all microcontroller’s input pins the logic level on when they are in idle
state. This level depends on the position of the pull-up/pull-down jumper. The P0.0 pin with the relevant jumper J2 and
P0.0 push button with jumper J17 are used here for the purpose of explaining the performance of pull-up/pull-down
resistors. The principle of their operation is the same for all other microcontroller pins.
In order to enable the PORT0 port pins to
be connected to pull-down resistors, it is
necessary to place jumper J1 in the Down
position first. This enables any PORT0 port
pin to be supplied with a logic zero (0V)
in idle state over jumper J2 and 8x10k
resistor network.
As a result, every time you press the P0.0
push button, the P0.0 pin will be fed with
a logic one (VCC-3.3 voltage), provided
that jumper J17 is placed in the VCC-3.3
position.
VCC-3.3
J2
P0.14
RN2 8x10K
R27
220
VCC-3.3
J17
J16 P0.14
3.3V
0V
up
pull
down
LPC2148
P1.27
P0.31
GND P0.
0
P1.31 P0.
1
P0.
2
VCC3 P1.26 GND P0.
3
P0.
4
P1.25 P0.
5
P0.
6
P0.
7
P1.24
VREF XT
AL1
XT
AL2
P1.28 GNDA P0.23 RESET P1.29 P0.20 P0.19 P0.18 P1.30 VCC3
GND VBA
T
P0.21 P1.20
P0.17
P0.16
P0.15
P1.21
VCC3
GND
P0.14
P1.22
P0.13
P0.12
P0.11
P1.23
P0.10
P0.9
P0.8
P0.22
RTXC1
P1.19
RTXC2
GND
VCCA
P1.18
P0.25
D+
D-
P1.17
P0.28
P0.29
P0.30
P1.16
VCC3
In order to enable port PORT0 pins to be
connected to pull-up resistors and the port
input pins to be supplied with a logic zero
(0), it is necessary to place jumper J2 in
the Up position and jumper J17 in the GND
position. This enables any port PORT0
input pin, when it is in idle state, to be
driven high (3.3V) over the 10k resistor.
As a result, every time you press the P0.0
push button, the P0.0 pin will be fed with a
logic zero (0V)
In case that jumpers J2 and J17 are in the
same positions, pressure on any button will
not cause input pins to change their logic
state.
Figure 14-6 : Jumper J2 in pull-down and jumper J17 in pull-up position
Figure 14-7: Jumper J2 in pull-up and jumper J17 in pull-down position
Figure 14-8: Jumpers J2 and J17 in the same positions