Pada ic atmega 8535 mempunyai pin untuk conversi analog to digital yaitu terletak pada pinA0 - pinA7.
rumus ADC [ (Vin + 1024)/Vreff --> 10 bit atau (Vin + 256)/Vreff --> 8 bit].
Sebagai simulasi kita gunakan program Proteus.
Langkah - langkah :
1. Buka program cvavr lalu ikuti langkah berikut
2. Buka aplikasi proteus, lalu susun rangkaian seperti dibawah ini.
IC atmega 8535, Led, dan POT-HG ( var-res)
3. Program
/*****************************************************
This program was produced by the
CodeWizardAVR V1.25.3 Standard
Automatic Program Generator
© Copyright 1998-2007 Pavel Haiduc, HP InfoTech s.r.l.
http://www.hpinfotech.com
Project :
Version :
Date : 3/24/2013
Author : F4CG
Company : F4CG
Comments:
Chip type : ATmega8535
Program type : Application
Clock frequency : 4.000000 MHz
Memory model : Small
External SRAM size : 0
Data Stack size : 128
*****************************************************/
#include <mega8535.h>
#include <delay.h>
#define ADC_VREF_TYPE 0x60
int reff = 150 ;
// Read the 8 most significant bits
// of the AD conversion result
unsigned char read_adc(unsigned char adc_input)
{
ADMUX=adc_input | (ADC_VREF_TYPE & 0xff);
// Start the AD conversion
ADCSRA|=0x40;
// Wait for the AD conversion to complete
while ((ADCSRA & 0x10)==0);
ADCSRA|=0x10;
return ADCH;
}
// Declare your global variables here
void main(void)
{
// Declare your local variables here
// Input/Output Ports initialization
// Port A initialization
// Func7=In Func6=In Func5=In Func4=In Func3=In Func2=In Func1=In Func0=In
// State7=T State6=T State5=T State4=T State3=T State2=T State1=T State0=T
PORTA=0x00;
DDRA=0x00;
// Port B initialization
// Func7=In Func6=In Func5=In Func4=In Func3=In Func2=In Func1=In Func0=In
// State7=T State6=T State5=T State4=T State3=T State2=T State1=T State0=T
PORTB=0x00;
DDRB=0x00;
// Port C initialization
// Func7=In Func6=In Func5=In Func4=In Func3=In Func2=In Func1=In Func0=In
// State7=T State6=T State5=T State4=T State3=T State2=T State1=T State0=T
PORTC=0x00;
DDRC=0x00;
// Port D initialization
// Func7=Out Func6=Out Func5=Out Func4=Out Func3=Out Func2=Out Func1=Out Func0=Out
// State7=0 State6=0 State5=0 State4=0 State3=0 State2=0 State1=0 State0=0
PORTD=0x00;
DDRD=0xFF;
// Timer/Counter 0 initialization
// Clock source: System Clock
// Clock value: Timer 0 Stopped
// Mode: Normal top=FFh
// OC0 output: Disconnected
TCCR0=0x00;
TCNT0=0x00;
OCR0=0x00;
// Timer/Counter 1 initialization
// Clock source: System Clock
// Clock value: Timer 1 Stopped
// Mode: Normal top=FFFFh
// OC1A output: Discon.
// OC1B output: Discon.
// Noise Canceler: Off
// Input Capture on Falling Edge
// Timer 1 Overflow Interrupt: Off
// Input Capture Interrupt: Off
// Compare A Match Interrupt: Off
// Compare B Match Interrupt: Off
TCCR1A=0x00;
TCCR1B=0x00;
TCNT1H=0x00;
TCNT1L=0x00;
ICR1H=0x00;
ICR1L=0x00;
OCR1AH=0x00;
OCR1AL=0x00;
OCR1BH=0x00;
OCR1BL=0x00;
// Timer/Counter 2 initialization
// Clock source: System Clock
// Clock value: Timer 2 Stopped
// Mode: Normal top=FFh
// OC2 output: Disconnected
ASSR=0x00;
TCCR2=0x00;
TCNT2=0x00;
OCR2=0x00;
// External Interrupt(s) initialization
// INT0: Off
// INT1: Off
// INT2: Off
MCUCR=0x00;
MCUCSR=0x00;
// Timer(s)/Counter(s) Interrupt(s) initialization
TIMSK=0x00;
// Analog Comparator initialization
// Analog Comparator: Off
// Analog Comparator Input Capture by Timer/Counter 1: Off
ACSR=0x80;
SFIOR=0x00;
// ADC initialization
// ADC Clock frequency: 1000.000 kHz
// ADC Voltage Reference: AVCC pin
// ADC High Speed Mode: Off
// ADC Auto Trigger Source: None
// Only the 8 most significant bits of
// the AD conversion result are used
ADMUX=ADC_VREF_TYPE & 0xff;
ADCSRA=0x82;
SFIOR&=0xEF;
while (1)
{
if ((read_adc(0)< reff)&&(read_adc(1)< reff)&&(read_adc(2)< reff)&&(read_adc(3)< reff)){PORTD = 0b000000000;}
if ((read_adc(0)>= reff)&&(read_adc(1)< reff)&&(read_adc(2)< reff)&&(read_adc(3)< reff)){PORTD = 0b000000001;}
if ((read_adc(0)< reff)&&(read_adc(1)>= reff)&&(read_adc(2)< reff)&&(read_adc(3)< reff)){PORTD = 0b000000010;}
if ((read_adc(0)< reff)&&(read_adc(1)< reff)&&(read_adc(2)>= reff)&&(read_adc(3)< reff)){PORTD = 0b000000100;}
if ((read_adc(0)< reff)&&(read_adc(1)< reff)&&(read_adc(2)< reff)&&(read_adc(3)>= reff)){PORTD = 0b000001000;}
if ((read_adc(0)< reff)&&(read_adc(1)>= reff)&&(read_adc(2)>= reff)&&(read_adc(3)< reff)){PORTD = 0b000000110;}
if ((read_adc(0)>= reff)&&(read_adc(1)>= reff)&&(read_adc(2)< reff)&&(read_adc(3)< reff)){PORTD = 0b000000011;}
if ((read_adc(0)< reff)&&(read_adc(1)< reff)&&(read_adc(2)>= reff)&&(read_adc(3)>= reff)){PORTD = 0b000001100;}
if ((read_adc(0)< reff)&&(read_adc(1)>= reff)&&(read_adc(2)>= reff)&&(read_adc(3)>= reff)){PORTD = 0b000001110;}
if ((read_adc(0)>= reff)&&(read_adc(1)>= reff)&&(read_adc(2)>= reff)&&(read_adc(3)< reff)){PORTD = 0b000000111;}
// Place your code here
};
}
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