COMSATS UNIVERSITY ISLAMABAD
MICROPROCESSOR SYSTEMS
AND INTERFACING
LAB
REPORT #09
SUBMITTED TO:
SIR KHIYAM IFTIKHAR
SUBMITTED BY: -
|
S/NO |
NAME |
REG NO |
|
1 |
JUNAID AHMAD |
CIIT/FA19-BEE-089/ISB |
|
2 |
IBRAR AHMAD |
CIIT/FA19-BEE-083/ISB |
|
3 |
JARRAR MALIK |
CIIT/FA19-BEE-087/ISB |
DATE:
26-11-2021
Lab # 09 Using
Timers/Counters of AVR MCU for
Waveform Generation
Objectives:
•
To
Introduction to Timers/Counters
•
Delay
and Waveform generation using timers
•
Using
PWM signals to control Servo Motors
•
Software
Tools:
•
Microchip
Studio/AVR Studio
•
Arduino
•
Proteus ISIS
•
AVR DUDESS
Hardware Tools:
|
Name |
Value |
Quantity |
|
Arduino Nano |
- |
1 |
|
Potentiometer |
- |
1 |
|
Servo Motor |
- |
1 |
|
Oscilloscope |
|
1 |
Table
7.1: List of Components
Task 1:
A
servomotor is connected to Timer OC0 pin and a potentiometer is connected to
ADC channel 0. Generate a PWM wave at Timer 0. The duty cycle of generated
waveform should vary according to the input voltage at channel 0 of the ADC
(The duty cycle should vary as you rotate the Potentiometer). By varying the
On-Time of the signal the servo can be rotated to different positions.
IN-LAB TASKS:
TASK 1:
A
servomotor is connected to Timer OC0 pin, and a potentiometer is connected to
ADC channel 0. Generate a PWM wave at Timer 0. The duty cycle of generated
waveform should vary according to the input voltage at channel 0 of the ADC
(The duty cycle should vary as you rotate the Potentiometer). By varying the
On-Time of the signal the servo can be rotated to different positions.
CODE
*
Created: 25/11/2020 9:10:39 PM
* Author : Aegon
*/
#include <inttypes.h>
#include <stdlib.h>
#include <avr/io.h>
#define F_CPU 16000000UL
#include <util/delay.h>
#include <string.h>
#include <math.h>
#define ADC_CHANNEL0 0
#define ADC_VREF 5 // Ref voltage for ADC is 5 Volts
#define ADC_RES 10 // Resoulution of ADC in bits
#define ADC_QLEVELS 1024 // Quantization levels for the ADC
unsigned char
ADC_Initialize(); // Initialize ADC. Mode 1 = Single Conversion, Mode 2 =
Free Running
unsigned int ADC_Read(unsigned char channel); // Reads the result of a
single conversion from the ADC
/******************* Function
Prototypes ***********
**********/
void init_timer0(); // Initialize Timer0 for
Fast PWM mode
void move_motor(int adc_value); // vlaue = 0 to 1023
for90 to 90 degrees angle
#define SERVO_OCR OCR0A
#define MIN_ANGLE_OCR 17.0
#define SERVO_OCR_OFFSET 14.0
// ***********************************************************
// Main program
int main(void)
{ init_timer0(); // timer0 configured for
Fast PWM mode
ADC_Initialize();
int adc_value;
while(1)
{ // Infinite loop; define here the
adc_value = ADC_Read(0);
_delay_ms(20);
// Set motor Position
move_motor(adc_value);
}}
void init_timer0()
{ OCR0A = (unsigned char) SERVO_OCR;
DDRD|=(1<<PD6);//
Configure OC0A for output(PortD.6)
TCCR0A|=0x83;//Initialize
timer0 for Fast PWM Mode, Non inverting,
TCCR0B|=0x05;// Set
Prescaler = 1024
}
/* Function Initializes the ADC for
10
Bit Single Conversion mode*/
unsigned char ADC_Initialize()
{ DIDR0=0x00;
ADMUX|=(1<<REFS0)|(1<<ADLAR);// Left adjust result. Vref = AVCC = 5V
ADCSRA|=(1<<ADEN);
// Enable ADC
ADCSRA|=(1<<ADPS0)|(1<<ADPS1)|(1<<ADPS2);//Select the prescaler for 16 MHz System Clock
return(0); }
/* Function reads the result of a
single conversion from the ADC
channel given as an arg
ument*/
unsigned int ADC_Read(unsigned char channel)
{
unsigned char ADC_lo;
unsigned char ADC_hi;
unsigned int result;
ADMUX &= ~(0x07); // clear previous selction of channel
ADMUX |= channel; // Select the new channel
// Delay needed for the stabilization
of the ADC input voltage
_delay_us(10);
//wait for ADC to finish any ongoing
opeartion
while((ADCSRA & (1<<ADSC)) != 0);
ADCSRA |= (
1 << ADSC); //start conversion
while((ADCSRA & (1<<ADIF)) == 0);
ADCSRA |= (1<<ADIF); // clear the flag by writing 1 to it
//result = (ADCH<<8)|(ADCL
& 0xC0); // Left adjust result
ADC_lo = ADCL;
ADC_hi = ADCH;
result = (ADC_hi<<2)|(ADC_lo
>> 6);
// Right adjust result
return result; }
void move_motor(int adc_value) // vlaue = 0 to 1023
for-90 to 90 degrees angle
{ SERVO_OCR=((float)adc_value/1023)*17+14;
//if we use 8-bit timer then-90 degree (1 ms)
correspond toOCR
//value of approximately 14
}
PROTEUS -SIMULATION:
HARD-WARE:
Critical Analysis / Conclusion:
In this lab experiment we
got to know how to do interfacing of servo motor with Arduino and learned about
different types of mode. There are four different modes of operation of
Timer/Counter0 module are Normal Mode, Clear Timer on Compare Match (CTC) Mode,
Fast PWM Mode, Phase Correct PWM Mode. PWM and its important features, PWM is
pulse width modulation, and it is one of the most important mode of timer’s
mode, The fast Pulse Width Modulation or fast PWM mode (WGM01:0 = 3) provides a
high frequency PWM waveform generation option. The phase correct PWM mode
(WGM01:0 = 1) provides a high-resolution phase correct PWM waveform generation
option
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