ATmega8+PT100热敏电阻+AD824S proteus仿真与源程序

ID:274871 · 发表于 2018-1-11 16:59

pt100热敏电阻+AD824S放大并由ATmega8单片机主控的测温系统仿真原理图如下（proteus仿真工程文件可到本帖附件中下载）

ATmega8单片机源程序如下:

/*****************************************************
This program was produced by the
CodeWizardAVR V2.03.4 Standard
Automatic Program Generator
?Copyright 1998-2008 Pavel Haiduc, HP InfoTech s.r.l.
Project :
Version :
Date : 2011-4-16
Author :
Company :
Comments:
Chip type : ATmega8
Program type : Application
Clock frequency : 8.000000 MHz
Memory model : Small
External RAM size : 0
Data Stack size : 256
*****************************************************/
#include <mega8.h>
//#include <delay.h>
#include <stdlib.h>
#include <string.h>
// Alphanumeric LCD Module functions
#asm
.equ __lcd_port=0x18 ;PORTB
#endasm
#include <lcd.h>
#include <delay.h>
#define ADC_VREF_TYPE 0xC0
#define MCPCS PORTD.0
#define MCPSCK PORTD.1
#define MCPDATA PIND.2
#define A 3.9083e-3
#define B -5.775e-7
#define C -4.183e-12
unsigned long read_spi(void);
float CalTem(float PT100R)
{
double fT,fR,fT0;
char i=0;
fR=PT100R;
fT0=(fR/100-1)/A;
if ((fR>=80.31)&&(fR<100)) //-30~0 度
{
for(i=0;i<50;i++)
{
fT=fT0+(fR-100*(1+A*fT0+B*fT0-100*C*fT0*fT0+C*fT0*fT0*fT0))/
(100*(A+2*B*fT0-300*C*fT0*fT0+4*C*fT0*fT0*fT0));
if(fabs(fT-fT0)<0.001) break;
else
fT0=fT;
}
} else if(fR>=100&&fR<=390.481) // 0~850 度
{
for (i=0;i<50;i++)
{
fT=fT0+(fR-100*(1+A*fT0+B*fT0*fT0))/(100*(A+2*B*fT0));
if (fabs(fT-fT0)<0.001) break;
else
fT0=fT;
}
} else fT=-1000.0;
return fT;
};
unsigned long read_mcp(void)
{
long a[]={0,0,0,0,0};
long x=0;
char i=0;
char k=5; // 数组大小 -1
for (i=0;i<5;i++)
{
a[i]=read_spi(); // 连续3次读出数据
delay_us(5);
}
//中值滤波
while (k>0)
{
for (i=0;(i<(k-1));i++) // 从低到高排序
{
if (a[i]>a[i+1])
{
x=a[i+1];
a[i+1]=a[i];
a[i]=x;
};
};
k--;
};
return a[2]; // 舍弃最大数据和最小数据。
}
unsigned long read_spi(void)
{
volatile char i=0;
volatile long int result=0,x=0;
MCPCS=0;// CS 先一个100us 低电平脉冲
delay_us(100);
MCPCS=1;
delay_ms(80); // 高电平等待80ms 等待转换完成
MCPCS=0; // 置 CS 低电平开始发生 sck 脉冲
for (i=0; i<24;i++) // 24 位数据
{
MCPSCK=0; // sck 脉冲下降沿
delay_us(1); // 等5us 等待稳定
//result=result<<1;
x=MCPDATA; // 读出一位
while (MCPDATA!=x) // 抖动处理 2次读出电平相同说明数据稳定
{
delay_us(1);
x=MCPDATA;
};
result<<=1;
result|=x;//(x<<(23-i));
delay_us(5);
MCPSCK=1; // 发送sck 上升沿
delay_us(10);
};
MCPCS=1; // cs=1
return result>>6;
}
// Read the AD conversion result
unsigned int read_adc(unsigned char adc_input)
{
ADMUX=adc_input | (ADC_VREF_TYPE & 0xff);
// Delay needed for the stabilization of the ADC input voltage
delay_us(10);
// Start the AD conversion
ADCSRA|=0x40;
// Wait for the AD conversion to complete
while ((ADCSRA & 0x10)==0);
ADCSRA|=0x10;
return ADCW;
}
// 校准温度计查表没20度一个校准，
// -50 -30 -10 10 30 50 70 90 110 130 150
const float CAL_Tem[]={4.7 ,4.65,4.65,4.6,4.6 ,4.55,4.55,4.50,4.45,4.45,4.45};
const int ADCSTEP[]={ 1 ,96 ,189 ,282, 374,466 ,557 ,648,738,827 ,916};
float CalcuTem(int ADC) // 温度校准计算没有使用
{
int i=0;
float r;
for (i=0; i<10;i++)
{
if ((ADC<ADCSTEP[i+1])&&(ADC>=ADCSTEP[i])) break;
};
r=(ADC-ADCSTEP[i]);
r=r/CAL_Tem[i];
r=r-50;///CAL_Tem[i]-50+i*20+;
r=r+i*20.0;
return r;
}
volatile char stradc[15]="\0";
void main(void)
{
// Declare your local variables here
volatile long int MCPADC=0;
volatile unsigned int adc=0;
volatile float fadc=0;
// Input/Output Ports initialization
// 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
// Func6=In Func5=In Func4=In Func3=In Func2=In Func1=In Func0=In
// 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=int Func1=out Func0=out
// State7=T State6=T State5=T State4=T State3=T State2=T State1=T State0=1
PORTD=0x07;
DDRD=0xFB;
// Timer/Counter 0 initialization
// Clock source: System Clock
// Clock value: Timer 0 Stopped
TCCR0=0x00;
TCNT0=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
MCUCR=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: 125.000 kHz
// ADC Voltage Reference: Int., cap. on AREF
ADMUX=ADC_VREF_TYPE & 0xff;
ADCSRA=0x86;
// LCD module initialization
lcd_init(16);
while (1)
{
MCPADC=0;
……………………
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