Tóm tắt : Qua bài này các bạn có thể sử dụng được ADC của AVR

Giới thiệu :

Phần cứng các bạn cần 1 con biến trở nối vào portA.0

Mạch ATmega16 như bài đầu .

Các chế độ sẽ chọn :

sử dụng chế độ ngắt ADC, tự động scan giá trị analog của port A

Ví dụ : Dùng PORTA.0 nhận giá trị từ biến trở hiển thị lên LCD theo ADC 8bit (từ 0->5V thành 0 ->255)

Chú ý :

trong chương trình có sử dụng hàm lcd_putnum(value); hiển thị chữ số

/*****************************************************

This program was produced by the

CodeWizardAVR V1.24.8d Professional

Automatic Program Generator

© Copyright 1998-2006 Pavel Haiduc, HP InfoTech s.r.l.

http://www.hpinfotech.com

Project :

Version :

Date : 1/9/2008

Author : LENGOCTUAN

Company : VAGAM

Comments:

Comments:

Chip type : ATmega16

Program type : Application

Clock frequency : 8.000000 MHz

Memory model : Small

External SRAM size : 0

Data Stack size : 256

*****************************************************/

#include

// Alphanumeric LCD Module functions

#asm

.equ __lcd_port=0x15 ;PORTC

#endasm

#include

#define FIRST_ADC_INPUT 0

#define LAST_ADC_INPUT 7

unsigned char adc_data[LAST_ADC_INPUT-FIRST_ADC_INPUT+1];

#define ADC_VREF_TYPE 0x20

// ADC interrupt service routine

// with auto input scanning

interrupt [ADC_INT] void adc_isr(void)

{

register static unsigned char input_index=0;

// Read the 8 most significant bits

// of the AD conversion result

adc_data[input_index]=ADCH;

// Select next ADC input

if (++input_index > (LAST_ADC_INPUT-FIRST_ADC_INPUT))

input_index=0;

ADMUX=(FIRST_ADC_INPUT|ADC_VREF_TYPE)+input_index;

// Start the AD conversion

ADCSRA|=0x40;

}

// Declare your global variables here

void lcd_putnum(unsigned int d)

{

unsigned char donvi, chuc, tram;

donvi=d%10;

d=d/10;

chuc=d%10;

d=d/10;

tram=d%10;

d=d/10;

if(tram>0)

{

lcd_putchar(48+tram);

lcd_putchar(48+chuc);

lcd_putchar(48+donvi);

}

else if(chuc>0)

{

lcd_putchar(48+chuc);

lcd_putchar(48+donvi);

lcd_putsf(" ");

}

else {

lcd_putchar(48+donvi);

lcd_putsf(" ");

lcd_putsf(" ");

}

}

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=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

PORTD=0x00;

DDRD=0x00;

// 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: AREF pin

// ADC Auto Trigger Source: None

// Only the 8 most significant bits of

// the AD conversion result are used

ADMUX=FIRST_ADC_INPUT|ADC_VREF_TYPE;

ADCSRA=0xCB;

// LCD module initialization

lcd_init(16);

// Global enable interrupts

#asm("sei")

lcd_gotoxy(0,0);

lcd_putsf("ADC");

while (1)

{

// Place your code here

lcd_gotoxy(4,1);

lcd_putnum(adc_data[0]);

};

}