Problem with LM35 (tempreture sensor) and Atmega32

Bluestar88 · Dec 7, 2014

I wanna measure the temperature of room. For this order I used a LM35 and Atmega32. But my circuit doesn't work correctly.It displays 499.5 C on it's LCD...Please help me...My code is here...

Code:

/****************************************************************
    Title                   : Thermometer with LM35
    Micro Contoroler        : ATMega32
    Clock frequency         : 1.000000 MHz
    Compiler                : Code Vision AVR
****************************************************************/

#include <mega32.h>
#include <delay.h>
#include <stdio.h>
#include <stdlib.h>
#include <delay.h>

// Alphanumeric LCD Module functions
#asm
   .equ __lcd_port=0x12 ;PORTD
#endasm
#include <lcd.h>

typedef unsigned char byte;
flash byte char0[8]={
    0b10000111,
    0b10000101,
    0b10000111,
    0b10000000,
    0b10000000,
    0b10000000,
    0b10000000,
    0b10000000
};

void Configuration_LCD(void);
void define_char(byte flash *pc,byte);
void Configuration_ADC(void);
void Display_LCD_Start(void);
float Read_adc(unsigned char);
float Convert(float);
void Display_LCD_1(float);
void Display_LCD_2(unsigned int);

float Input_mV=0;
float Temp=0;

void main(void){
    Configuration_ADC();
    Configuration_LCD();
    define_char(char0,0); 
    Display_LCD_Start();
    while (1){
        Input_mV=Read_adc(0);
        Temp=Convert(Input_mV);
        Display_LCD_1(Temp);
        Display_LCD_2(Input_mV);
        delay_ms(300);                                        
    };
}

//********************************************************
void Configuration_LCD(void){
    lcd_init(16); lcd_clear();   
}

//********************************************************
void define_char(byte flash *pc,byte char_code){
    byte i,a;
    a=(char_code<<3) | 0x40;
    for (i=0; i<8; i++) lcd_write_byte(a++,*pc++);
}

//********************************************************
void Configuration_ADC(void){
    // 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: AVCC pin
    ADMUX=0x40 & 0xff;
    ADCSRA=0x83;
}

//********************************************************
void Display_LCD_Start(void){
    lcd_clear(); 
    lcd_gotoxy(0,0); lcd_putsf("LM35");
    lcd_gotoxy(0,1); lcd_putsf("Test");
    delay_ms(2000); lcd_clear(); delay_ms(200);
}

//********************************************************
float Read_adc(unsigned char adc_input){
    float x=0;
    ADMUX=adc_input | (0x40 & 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;
    x=ADCW; x= x*4.8828125;
    return x;
}

//********************************************************
float Convert(float x){
     x=x/10;
     return x;
}

//********************************************************
void Display_LCD_1(float x){
    char buffer[16];
    lcd_gotoxy(0,0); 
    lcd_putsf("Temp: ");
    ftoa(x,1,buffer); lcd_puts(buffer); 
    lcd_putsf(" ");
    lcd_putchar(0);
    lcd_putsf("C");   
}

//********************************************************
void Display_LCD_2(unsigned int x){
    char buffer[16];
    lcd_gotoxy(0,1); 
    lcd_putsf("Input: ");
    ftoa(x,1,buffer); lcd_puts(buffer);
    lcd_putsf(" mV");
}

and my hardware is simple. I connected pin 10, 30 to VCC and 11, 31 to GND. Pin 40 to sensor. and PORT D to LCD....Please help me..I really confused...

- - - Updated - - -

It is such as a case that ADC doesnot work.....Please help me...

- - - Updated - - -

It is such as a case that ADC doesnot work.....Please help me...

milan.rajik · Dec 7, 2014

Read these.

http://www.electroschematics.com/10053/avr-adc/

http://www.ermicro.com/blog/?p=121

- - - Updated - - -

Read these.

http://www.electroschematics.com/10053/avr-adc/

http://www.ermicro.com/blog/?p=121

Bluestar88 · Dec 7, 2014

It seems to be correct, I don't know what's problem...

milan.rajik · Dec 7, 2014

Zip and post the code vision AVR project. I will test it in Proteus and also hardware.

ADC input pin configures as input and analog pin using DDRx ?

Bluestar88 · Dec 7, 2014

Nobody Can help me?

Easyrider83 · Dec 7, 2014

Try simulate your circuit in Proteus. There no way to damage any devices as I know ))

milan.rajik · Dec 7, 2014

When you click Reply button it open a page and in that click Manage Attachments button and attach your Zip file and make the post.

Post the complete CodeVision AVR project files Zipped including the lcd.h file.

Bluestar88 · Dec 9, 2014

My problem was because of atmega32. When I replaced it, My problem solved.

Now, I want to turn on the relay by setting PinB.0 on atmega32 and a 330 ohm resistor and a BC237 transistor. In my code if temp<30, PinB.0=1 then causes to turn on the relay an if temp>30, PinB.0=0 then relay turn off. But I have a problem when tempreature is oscillating between 29.8 to 30.3 relay is turn off and turn off, consecutively. My code is here. Please help me.

Code:

/****************************************************************
    Title                   : Thermometer with LM35
    Last Updated            : 2013/04/19
    Micro Contoroler        : ATMega32
    Clock frequency         : 1.000000 MHz
    Compiler                : Code Vision AVR
****************************************************************/

#include <mega32.h>
#include <delay.h>
#include <stdio.h>
#include <stdlib.h>
#include <delay.h>

// Alphanumeric LCD Module functions
#asm
   .equ __lcd_port=0x12 ;PORTD
#endasm
#include <lcd.h>

typedef unsigned char byte;
flash byte char0[8]={
    0b10000111,
    0b10000101,
    0b10000111,
    0b10000000,
    0b10000000,
    0b10000000,
    0b10000000,
    0b10000000
};

void Configuration_LCD(void);
void define_char(byte flash *pc,byte);
void Configuration_ADC(void);
void Display_LCD_Start(void);
float Read_adc(unsigned char);
float Convert(float);
void Display_LCD_1(float);
void Display_LCD_2(unsigned int);

float Input_mV=0;
float Temp=0;

void main(void){
       //PortA -> Output
    PORTB = 0x00;
    DDRB = 0x0f;
    Configuration_ADC();
    Configuration_LCD();
    define_char(char0,0); 
    Display_LCD_Start();
    while (1){
        Input_mV=Read_adc(0);
        Temp=Convert(Input_mV);
        Display_LCD_1(Temp);
        Display_LCD_2(Input_mV);   
        
[B]         if(Temp>30)
        {
         PORTB.0=1;  
         }
          if (Temp<30)
         {
         PORTB.0=0;   
         } 
         [/B]
        delay_ms(300);                                        
    };
}

//********************************************************
void Configuration_LCD(void){
    lcd_init(16); lcd_clear();   
}

//********************************************************
void define_char(byte flash *pc,byte char_code){
    byte i,a;
    a=(char_code<<3) | 0x40;
    for (i=0; i<8; i++) lcd_write_byte(a++,*pc++);
}

//********************************************************
void Configuration_ADC(void){
    // 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: AVCC pin
    ADMUX=0x40 & 0xff;
    ADCSRA=0x83;
}

//********************************************************
void Display_LCD_Start(void){
    lcd_clear(); 
    lcd_gotoxy(0,0); lcd_putsf("www.CSANCO.COM");
    lcd_gotoxy(0,1); lcd_putsf("LM35");
    delay_ms(2000); lcd_clear(); delay_ms(200);
}

//********************************************************
float Read_adc(unsigned char adc_input){
    float x=0;
    ADMUX=adc_input | (0x40 & 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;
    x=ADCW; x= x*4.8828125;
    return x;
}

//********************************************************
float Convert(float x){
     x=x/10;
     return x;
}

//********************************************************
void Display_LCD_1(float x){
    char buffer[16];
    lcd_gotoxy(0,0); 
    lcd_putsf("Temp: ");
    ftoa(x,1,buffer); lcd_puts(buffer); 
    lcd_putsf(" ");
    lcd_putchar(0);
    lcd_putsf("C");   
}

//********************************************************
void Display_LCD_2(unsigned int x){
    char buffer[16];
    lcd_gotoxy(0,1); 
    lcd_putsf("Input: ");
    ftoa(x,1,buffer); lcd_puts(buffer);
    lcd_putsf(" mV");
}

milan.rajik · Dec 9, 2014

Try this.

Code C - [expand]
1
2
3
4
5
6
7
8
if(Temp >= 30)
        {
         PORTB.0 = 1;  
         }
          if (Temp < 30)
         {
         PORTB.0 = 0;   
         }

paulfjujo · Dec 9, 2014

hello

try to add hystereis behavior
so you get a dead band around 30.0°

Code:

// inital value;
hysteresis=0.1;  // less or more than 0.1 !



if(Temp >= 30+ hysteresis)
        {
         PORTB.0 = 1;  
         hysteresis=-0.1;
         }
          if (Temp < 30 - Hysteresis)
         {
         PORTB.0 = 0;
         hysteresis=+0.1;
         }

Problem with LM35 (tempreture sensor) and Atmega32

Bluestar88

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milan.rajik

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Bluestar88

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milan.rajik

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Bluestar88

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Easyrider83

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Bluestar88

milan.rajik

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milan.rajik

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paulfjujo

Advanced Member level 4

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Code C - [expand]
1 2 3 4 5 6 7 8	if(Temp >= 30) { PORTB.0 = 1; } if (Temp < 30) { PORTB.0 = 0; }

Problem with LM35 (tempreture sensor) and Atmega32

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