AIM: Sense
key and activate following devices.
Sense key from P0.0
|
Activate LED and
Relay connected at P0.3 and P0.6 resp.
|
Sense key from P0.1
|
Activate LED and
Relay connected at P0.4 and P0.7 resp.
|
Sense key from P0.2
|
Activate Buzzer
connected at P0.5.
|
THEORY:
Sensing a key connected directly to a
pin is simple. We need to read the port to which the key is connected and then
test the bit corresponding to the pin connected to the key.
For sensing a key and activating LED
based on the key state, we need to,
1. Set
the pin functions as I/O. For this we used PINSEL0 register.
2. Set
the directions of P0.0, P0.1 and P0.2 as input since, the keys are connected to
these pins.
3. Set
the directions of pins P0.3, P0.4, P0.5, P0.6 and P0.7 as output since, these
are connected to LED, Buzzer and Relay respectively.
PROCEDURE:
For
creating project, we need to take following steps.
1) Create new project
2) Algorithm
3) Simulation of Algorithm
These
three steps are involved in procedure.
1) Create new project
1. Select
a new project and give particular name to that project. e.g key_sensing
2. Select
chip NXP (founded by Philips) LPC2148.
3. For
assembly language don’t add startup file.
4. Select
a new editor file, write logic in that file and save it by using .c extension in embedded c language.
2) Algorithm
Algorithm
consists of following steps.
Key sensing:
1. Select
pin function
2. Set
the direction of the port
3. Make
particular pin high by using IOSET.
4. Clear
pins by using IOCLR.
3) Simulation of Algorithms
It
consists of following steps.
1.
After writing program just build it.
2. If
there are any errors, they will be due to some mistake in typing the program.
To locate the error, double click on the first error. Check for the
error and remove it. Repeat this till all errors are gone.
3. Now
it’s time to debug. Click on the
debug tab and debug program and observe contents of the variables in embedded c
programming.
OBSERVATIONS:
1. Observe
pins P0.0, P0.1 and P0.2 connected to key & working as a input
2. Observe
pins P0.3 and P0.4 connected to LEDs.
3. Observe
pin P0.5 connected to Buzzer.
4. Observe
pins P0.6 and P0.7 connected to relays.
Sense
key and activate devices.
In
Embedded c:
#include
<LPC214X.H>
int
main(void)
{
PINSEL0=00;
IODIR0=0x000000F8;
while(1)
{
if(IOPIN0 & 0x00000001)
{
IOCLR0 = 0x00000048;
}
else
{
IOSET0 = 0x00000048;
}
if(IOPIN0 & 0x00000002)
{
IOCLR0 = 0x00000090;
}
else
{
IOSET0 = 0x00000090;
}
if(IOPIN0 & 0x00000004)
{
IOCLR0 = 0x00000020;
}
else
{
IOSET0 = 0x00000020;
}
}
}
Port Pin output:
Proteus
design:
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