[PIC] adc conversion using pic 12f675

[Gopi Vh]

help me out i am not able to read the adc value .
i am reading adc value from analog channel 2
here my code is there

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Code C - [expand]
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/* adc conversion*/
   unsigned char adc_value;
unsigned char sensor;
char *text="00000";
const gas_max = 642;
void main()
{
 
 ADCON0 =0x08;
ANSEL =0b00000110;
ADRESH =0;
ADRESL =0;
CMCON = 7;
 GPIO=0;        //clear all pins
TRISIO.B2=1;    //ip
TRISIO.B1=0;        //op
TRISIO.B0=0;        //op
TRISIO.B5 =0;     //op
 
while(1)
{
 
adc_value=adc_read(2);
 adc_value= (((unsigned int)ADRESH<< 8)| (ADRESL));
 sensor =(553 - (adc_value-61));
 delay_ms(200);
if(sensor < gas_max)
{
 
  GPIO.B1=1; //green led;
  delay_ms(20);
}
else
{
 delay_ms(20);
    GPIO.B0 = 1;  //red led
 
    GPIO.B5 = 1;    //buzzer
}
 
 
 
    }
   }

---

 

[ud23]

ANSEL =0b00000100;

If you need one pin as just analog input(BN2) and rest as digital output.

 

[paulfjujo]

hello,

and use an "int " to store and use the 10 bits adc result...

 

[Gopi Vh]

its not yet working
i am using that for gas sensor
i used the above correction but still its not reading the analog ip value from mc

 

[ud23]

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/* adc conversion*/
   unsigned int adc_value;
unsigned int sensor;
char *text="00000";
const gas_max = 642;
void main()
{
 
 ADCON0 =0x08;
ANSEL =0b00000100;
ADRESH =0;
ADRESL =0;
CMCON = 7;
 GPIO=0;        //clear all pins
TRISIO.B2=1;    //ip
TRISIO.B1=0;        //op
TRISIO.B0=0;        //op
TRISIO.B5 =0;     //op
 
while(1)
{
 
adc_value=adc_read(2);
 adc_value= (((unsigned int)ADRESH<< 8)| (ADRESL));
 sensor =(553 - (adc_value-61));
 delay_ms(200);
if(sensor < gas_max)
{
 
  GPIO.B1=1; //green led;
  delay_ms(20);
}
else
{
 delay_ms(20);
    GPIO.B0 = 1;  //red led
 
    GPIO.B5 = 1;    //buzzer
}
 
 
 
    }
   }

---

try this code what is your output read result?

 

[paulfjujo]

hello,

did you test ,before , your program ADC reading, by using a potentiometer ( <= 4,7K) powered by VCC.
Because you can have some probleme with your Gas sensor itself, needs high impedance ADC input to
give a correct signal.