Does anyone know on how to initialize ADC on ATMEGA128 ?

[bianchi77]

Hello guys,

Does anyone know on how to initialize ADC on ATMEGA128 ?
Any references will be appreciated,

thank you

 

[tpetar]

ftp://kavcrl.dyndns.org/+MEDIA/experiments/our/kav_most/gener&inter/gen+avr/a2d_atmega128.pdf

MikroC for AVR - ADC Library
**broken link removed**

 

[bianchi77]

I tried to init like this :

void adc_init()
{
	// enable ADC, select ADC clock = F_CPU / 128 (i.e. 125 kHz)

	ADCSRA = (1<<ADEN | 1<<ADPS2 | 1<<ADPS1 | 1<<ADPS0 );

	//Do a conversion to get rid of rubbish

	ADMUX=(1<<REFS0 | ADC_7);                  //Conversion on channel 7, thermistor input
	//Internal VCC Voltage Reference
	ADCSRA |= (1<<ADSC);                      //Start conversion
	loop_until_bit_is_clear(ADCSRA, ADSC);    //Wait for conversion complete
}


uint8_t read_adc(void)
{
	ADMUX=(1<<REFS0) | (1<<ADLAR) | ADC_0;                  // Conversion on channel 0, AVCC reference, 10 bit mode
	ADCSRA |= (1<<ADSC);                     // Start conversion
	loop_until_bit_is_clear (ADCSRA, ADSC);         // Wait for conversion complete
	return(ADCH);
}
.
.
main
{

	char volts[50];
	uint8_t  adc_result=0;
	double adcA=0.0;
 adc_result=read_adc();
			  adcA = (int)(adc_result*5.0)/1024.0;
			  if (adcA != 0)
			   {
				  sprintf(volts,"%0.2f",adcA);
				  lcd_string(volts);
				  _delay_ms(1000);
			   }
			   else
			   {
				     lcd_string("No Result!");
					 _delay_ms(2000); 
			   }
}

I got "?" in my LCD, do I miss something here ?

I connect to ADC like this :


R1 = Trimpot 10 K
R2 = 4K7

Vin connected to PF0 or ADC0 on atmega 128,

anyone has ideas ?

thanks

 

[bianchi77]

My complete code, please correct me if I'm wrong,
How to change custom option on configuration on AVR Studio 6 ?

Thank you

/*
 * ADC_test.c
 *
 * Created: 24/05/2013 2:01:57 PM
 *  Author: Antonius
 */ 
//Mention Clock frequency here
#define _XTAL_FREQ 8000000
#define F_CPU 8000000UL  // 8 MHz

#include <avr/io.h>
#include <util/delay.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>


// structure to allow bit field operations, name conversions: PORTA.0 -> PORT_A.b0  PORTB.7 -> PORT_B.b7
typedef struct{ uint8_t b0:1;
	uint8_t b1:1;
	uint8_t b2:1;
	uint8_t b3:1;
	uint8_t b4:1;
	uint8_t b5:1;
	uint8_t b6:1;
uint8_t b7:1; } bits;

// define all the ports of your microcontroller, add more ports depending on the available mcu ports
#define PORT_D (* (volatile bits *) &PORTD)
#define PIN_D (* (volatile bits *) &PIND)
#define DDR_D (* (volatile bits *) &DDRD)

#define PORT_G (* (volatile bits *) &PORTG)
#define PIN_G (* (volatile bits *) &PING)
#define DDR_G (* (volatile bits *) &DDRG)

#define lcd_data_pin PORTA

#define en PORT_D.b0
#define rs PORT_D.b1
#define rw PORT_D.b2
#define relay1 PORT_D.b3
#define relay2 PORT_D.b4

// //ADC definitions
#define   ADC_0 0
#define   ADC_1 1
#define   ADC_2 2
#define   ADC_3 3
#define   ADC_4 4
#define   ADC_5 5
#define   ADC_6 6
#define   ADC_7 7

#define ADC_VREF_TYPE 0x00

void lcd_init();
void lcd_data(unsigned char data1);
void lcd_cmd(unsigned char cmd);
void lcd_control(unsigned char cmdordata);
void lcd_string(unsigned char *str);
void adc_init(void);
uint16_t read_adc(void);




void adc_init()
{
	// enable ADC, select ADC clock = F_CPU / 128 (i.e. 125 kHz)

	ADCSRA = (1<<ADEN | 1<<ADPS2 | 1<<ADPS1 | 1<<ADPS0 );

	//Do a conversion to get rid of rubbish

	ADMUX=(1<<REFS0 | ADC_0);                  //Conversion on channel 0, thermistor input
	//Internal VCC Voltage Reference
	ADCSRA |= (1<<ADSC);                      //Start conversion
	loop_until_bit_is_clear(ADCSRA, ADSC);    //Wait for conversion complete
}


uint16_t read_adc(void)
{
	ADMUX=(1<<REFS0) | (1<<ADLAR) | ADC_0;                  // Conversion on channel 0, AVCC reference, 10 bit mode
	ADCSRA |= (1<<ADSC);                     // Start conversion
	loop_until_bit_is_clear (ADCSRA, ADSC);         // Wait for conversion complete
	return(ADCH);
}




void lcd_init(){
	
	lcd_cmd(0x30);
	_delay_ms(10);
	lcd_cmd(0x38);
	_delay_ms(10);
	lcd_cmd(0x0F);
	_delay_ms(10);
	lcd_cmd(0x80);
	_delay_ms(10);

}

void lcd_data(unsigned char data1)
{
	
	
	lcd_data_pin = data1;// & 0x0F;
	en=1;
	rs=1;
	rw=0;
	_delay_ms(10);
	en=0;
	
}

void lcd_cmd(unsigned char cmd){
	lcd_data_pin = cmd ;
	
	en=1;
	rs=0;
	rw=0;
	_delay_ms(10);
	en=0;
	
}



void lcd_string(unsigned char *str){
	
	while(*str){
		lcd_data(*str++);
	}
	
}





int main(){
	char volts[50];
	int  adc_result;
	float adcA;
	
	DDR_D.b0 = 1;
	DDR_D.b1 = 1;
	DDR_D.b2 = 1;
	DDR_D.b3 = 1;
	DDR_D.b4 = 1;
	DDRA = 0xFF;
	
	lcd_init();
	adc_init();
	
	while(1){
		
			lcd_cmd(0x80);//put the cursor into the first row
			_delay_ms (10);
			lcd_cmd(0x01);//Clear display
			_delay_ms (10);
			lcd_string("ADC Value");
			lcd_cmd(0xC0);//goto second row
			//lcd_string("Value of PF0");
			_delay_ms(1000);
			//check the adc result begin
			adc_result=read_adc();
			adcA = (int)(adc_result*5.0)/1024.0;
			
			if (adcA != 0)
			{
				 //itoa(adcA,volts,5);
				sprintf(volts,"adc=%.3f",adcA);
				lcd_string(volts);
				_delay_ms(1000);
			}
			else
			{
				lcd_string("No Result!");
				_delay_ms(2000);
			}
			//check the adc result end

		

		
	}//end while
	
	return (0);
}//end main