Download Experiment 3 - LED Lights Controller

KULLIYYAH OF ENGINEERING
DEPARTMENT OF ELECTRICAL AND COMPUTER ENGINEERING
SEMESTER II 2014/2015
Laboratory Manual
ECE 4102
Computer and Information Engineering
Lab II
EXPERIMENT 3
Microcontroller Programming:
Using PIC16F88 Kit-Lights Control using
LDR
1. Objectives
To program the PIC16F88 microcontroller for the application of lights control
using LDR sensor.
2. Contents
Microcontroller
PIC16F88
Kit
is
designed
for
training
in
Microcontroller
programming. This Kit consists of Programmer and Application Circuit in one
unit. Firstly, the source code program is written according to the desired
algorithm. Then students need to download their own programs into the
microcontroller. After downloading, the designed program can be executed by
microcontroller in Application circuit to test whether the circuit is running as
desired or not.
Figure 1. Application Circuit of PIC16F88 Kit.
In this experiment, students need to write their own program to control the LEDs
lights using the LDR (light dependent resistance) sensor. Thus, we will
understand how the microcontroller is used to read analog data from the sensor.
LDR is an optoelectronic sensor, that response to light intensity. The higher the
light intensity, the lower the resistance of the LDR. This resistance is converted
to voltage by using voltage divider circuit. This voltage signal is then acquired
by the microcontroller.
3. Reading data from sensor
PIC16F88 can be used as IC for data acquisition since it has Analog Digital
Converter Port, available 6 analog inputs on PORT AN0 to AN6.
MikroC has library to operate ADC function:
1. Adc_Read
This is to start analog port reading.
Command: Adc_Read(No. of channel_analog_port);
2. ADCON1
To activate conversion from analog to digital
Command: ADCON1 = 0; activate ADC on all analog ports
4. Instructions of experiment
Complete the laboratory work as follows (work in group of 2 persons):
a) Write your own program to control LED lights using LDR following this
algorithm:
i. Set initial value of PORT that will be used.
ii. Define PORT that will be used as input and output.
iii. Select the analog input port.
iv. Activate ADC in all analiog ports.
v. Read analog data from LDR
b) Download the program and show to the instructor your testing result.
c) Submit the lab report including the program (source code), due one week
after laboratory. In your report, explain what the program actually does
and describe the scenario.
/* Name of Program: ADC
Connection: LED B0-M, B1-K, B2-H, B3-M, B4-K, B5-H
B6_SW1, B7-SW2
A1-Buzzer
A0=LDR
*/
unsigned short input_a0;
void main()
{
PORTB = 0;
//initial PORTB=0
PORTA = 0;
//initial PORTA=0
//SET PORT B as INPUT or OUTPUT
TRISB.F0 = 0;
TRISB.F1 = 0;
TRISB.F2 = 0;
TRISB.F3 = 0;
TRISB.F4 = 0;
TRISB.F5 = 0;
//PORT B0 as Output
//PORT B1 as Output
//PORT B2 as Output
//PORT B3 as Output
//PORT B4 as Output
//PORT B5 as Output
TRISB.F6 = 1;
//PORT B6 as input
TRISB.F7 = 1;
//PORT B7 as input
//SET PORT A1 as OUTPUT
TRISA.F1 = 0;
//Analog Selection
ANSEL.F5 = 0;
//Set AN5 as digital
ANSEL.F6 = 0;
//Set AN6 as digital
ANSEL.F0 = 1;
//Set A1 as analog input
ADCON1 = 0; //activate ADC on all analog ports
{
do
{
input_a0 = ADC_Read(0);
PORTB = input_a0;
}
while(1);
}
}
// get analog data from A0
//binary value PORTB = analog data A0
The effect on the light intensity can be seen in LED lights in PORT B0 to B5. For
example: If LEDs are ON in pin RB3, RB2, RB1, RB0.
Binary value is: 00001111
PORTB = RB7 RB6 RB5 RB4 RB3 RB2 RB1 RB0
We can use Qconverter in MikroC: 00001111(binary) is equal to 15 (decimal).
This decimal 15 is equivalent to 15/255 x 5 V= 0.29 V.
(Note: that 1111111 (binary)=255(decimal).
That means the output voltage of LDR sensor is 0.29V.