problem facing to use ADC conversion in ATMEGA16(xtal 12mhz)

[Nirav Tejani]

Hello Friends,

                 I am totally confused by this problem.I am using ADC1 channel to give analog input with stable voltage input.My problem is that I am getting approximately same converted value for different voltage inputs.And yah i am using single conversion mode..Pls check my code…And let me know my problem,,,,,

CODE:

#include<avr/io.h>
#include<stdlib.h>
#define F_CPU 12000000UL
#include<util/delay.h>
//#include”lcd.c”
#define INVERTER_SW PA0
#define POWER_PIN PD0

// ADC initialisation function //
void ADC_init()
{
 ADMUX=(1<<REFS1)|(REFS0);
ADCSRA=(1<<ADEN)|(1<<ADPS2)|(1<<ADPS1)|(1<<ADPS0);//for prescaler 128
}

//ADC read value function //
uint16_t ADC_read(unsigned char ch)
{
// uint16_t data;
ch=ch&0b00000111; //ch. must be between 0 to 7
ADMUX|=ch; //selecting channel
ADCSRA|=(1<<ADSC); //to start conversion
while(!(ADCSRA && (1<<ADIF)));
//waitnig to complete of conversion
ADCSRA|=(1<<ADIF); //to indicate of end of conversion
/* data=ADCL;
data=data + (ADCH << ;*/
// return (data);
return(ADC);
}

/* <<<<<<<<<<<<<<<<<<<<<<<<<< MAIN >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>> */
int main()
{
DDRD=0x00;
DDRA|=(1<<INVERTER_SW)|(1<<PA3)|(1<<PA2);
// DDRB|=(1<<PB0);
// DDRA=0x7F;
PORTD=0x00;
PORTA=0x00;
// DDRA=0xE0;
// DDRC=0Xff;
ADC_init();
uint16_t value;
// init_LCD();

while(1)
{

//LCD_cmd(0x01);
value=ADC_read(1);
//LCD_cmd(0x80);
//int_lcd(value);
_delay_ms(3000);

if(value<400)
{
PORTA|=(1<<PA3);
}
if(value >630)
{
PORTA|=(1<<INVERTER_SW);

}
if(value>0620)
{
PORTA|=(1<<PA2);
}
_delay_ms(2000);
PORTA&=~(1<<PA3);
PORTA&=~(1<<INVERTER_SW);
PORTA&=~(1<<PA2);

}

}

[Shrikant]

am not quite sure but just check your adc read function.. i feel that you need to clear the channel used previously..

so instead of ch=ch&0b00001111 try using the following

ADMUX&=0XF0; // basically 11110000 .. this is to clear the previous channels

ADMUX|=ch;

 

[AJISH ALFRED]

Hi Nirav,

Make sure that you’ve connected the reference pin of the ADC to 5V.

[Nirav Tejani]

Thanks for your suggetion

 

         Now I am getting proper outputs .The problem is in my hardware.I was not applying proper ground to Adc pin thats the problem.

again thanks for your response.

 

[AJISH ALFRED]

You are welcome. Alll the best for your future projects

[Author]

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