Digital voltmeter with PIC16F876A

john120 · Aug 20, 2013

Hello there,can some body help me to know where the error is I am design a 0-30V digital voltmeter but I am always getting 0V on the seven segment display.

Here are the code and the proteus circuit.

PHP:

#include "16f876a.h"
#DEVICE ADC=10
#fuses XT,NOWDT,NOLVP,NODEBUG,NOCPD
#use delay(clock=4M)
#include<STDLIB.H>
#use standard_io(A)
#use standard_io(B)
#define PORTB
#DEFINE PORTC
#define PORTA

byte const digit[10]={0xC0,0xF9,0xA4,0xB0,0x99,0x92,0x82,0xF8,0x80,0x90};
 char display[3];
 unsigned int volt1,volt2;
int value;


void main()
{
set_tris_a(0xff);
set_tris_b(0x00);
set_tris_c(0x00);  

   while(TRUE){
   //setup_comparator(NC_NC_NC_NC);
   Setup_adc(ADC_CLOCK_DIV_8);
   setup_adc_ports(AN0);
   set_adc_channel(0);
   setup_vref(FALSE);
      delay_us(10);    
        read_adc(ADC_START_ONLY);
      delay_us(100);
      value=read_adc();
      volt2=(value*500)/1023;

       delay_ms(1);

      volt2=volt1;                
      output_low(PIN_b2);
      display[0]=volt1/10;      
      output_c(digit[display[0]]);
      output_high(PIN_b4);
    output_high(PIN_b5);
      delay_ms(10);

       output_low(PIN_b4);
      display[1]=volt1%10;      
      output_c(digit[display[1]]);
      output_high(PIN_b2);
     output_high(PIN_b5);
      delay_ms(10);

 	  output_low(PIN_b5);
      display[1]=volt1%10;      
      output_c(digit[display[1]]);
      output_high(PIN_b2);
	  output_high(PIN_b4);
      delay_ms(10);

}
}

Thanks.

Venkadesh_M · Aug 20, 2013

you put

Code C - [expand]
1
volt2 = volt1

instead of

Code C - [expand]
1
volt1 = volt2

and also

Code C - [expand]
1
output_c(digit[display[volt1]]);

mathespbe · Aug 20, 2013

john120 said:

Hello there,can some body help me to know where the error is I am design a 0-30V digital voltmeter but I am always getting 0V on the seven segment display.

Here are the code and the proteus circuit.

PHP:

#include "16f876a.h"
#DEVICE ADC=10
#fuses XT,NOWDT,NOLVP,NODEBUG,NOCPD
#use delay(clock=4M)
#include<STDLIB.H>
#use standard_io(A)
#use standard_io(B)
#define PORTB
#DEFINE PORTC
#define PORTA

byte const digit[10]={0xC0,0xF9,0xA4,0xB0,0x99,0x92,0x82,0xF8,0x80,0x90};
 char display[3];
 unsigned int volt1,volt2;
int value;


void main()
{
set_tris_a(0xff);
set_tris_b(0x00);
set_tris_c(0x00);  

   while(TRUE){
   //setup_comparator(NC_NC_NC_NC);
   Setup_adc(ADC_CLOCK_DIV_8);
   setup_adc_ports(AN0);
   set_adc_channel(0);
   setup_vref(FALSE);
      delay_us(10);    
        read_adc(ADC_START_ONLY);
      delay_us(100);
      value=read_adc();
      volt2=(value*500)/1023;

       delay_ms(1);

      volt2=volt1;                
      output_low(PIN_b2);
      display[0]=(volt1/10) ;      
      output_c(digit[display[0]]);
      output_high(PIN_b4);
    output_high(PIN_b5);
      delay_ms(10);

       output_low(PIN_b4);
      display[1]=(volt1%10) ;      
      output_c(digit[display[1]]);
      output_high(PIN_b2);
     output_high(PIN_b5);
      delay_ms(10);

 	  output_low(PIN_b5);
      display[1]=volt1%10;      
      output_c(digit[display[1]]);
      output_high(PIN_b2);
	  output_high(PIN_b4);
      delay_ms(10);

}
}

Thanks.

try this code...

Code:

#include "16f876a.h"
#DEVICE ADC=10
#fuses XT,NOWDT,NOLVP,NODEBUG,NOCPD
#use delay(clock=4M)
#include<STDLIB.H>
#use standard_io(A)
#use standard_io(B)
#define PORTB
#DEFINE PORTC
#define PORTA

byte const digit[10]={0xC0,0xF9,0xA4,0xB0,0x99,0x92,0x82,0xF8,0x80,0x90};
 char display[3];
 unsigned int volt1,volt2;
int value;


void main()
{
set_tris_a(0xff);
set_tris_b(0x00);
set_tris_c(0x00);  

   while(TRUE){
   //setup_comparator(NC_NC_NC_NC);
   Setup_adc(ADC_CLOCK_DIV_8);
   setup_adc_ports(AN0);
   set_adc_channel(0);
   setup_vref(FALSE);
      delay_us(10);    
        read_adc(ADC_START_ONLY);
      delay_us(100);
      value=read_adc();
      volt2=(value*500)/1023;

       delay_ms(1);

      volt1=volt2;                
      output_low(PIN_b2);
      display[0]=(volt1/10) + 30;      
      output_c(digit[display[0]]);
      output_high(PIN_b4);
    output_high(PIN_b5);
      delay_ms(10);

       output_low(PIN_b4);
      display[1]=(volt1%10) + 30;      
      output_c(digit[display[1]]);
      output_high(PIN_b2);
     output_high(PIN_b5);
      delay_ms(10);

 	  output_low(PIN_b5);
      display[1]=volt1%10;      
      output_c(digit[display[1]]);
      output_high(PIN_b2);
	  output_high(PIN_b4);
      delay_ms(10);

}
}

john120 · Aug 20, 2013

mathespbe said:

try this code...

Code:

#include "16f876a.h"
#DEVICE ADC=10
#fuses XT,NOWDT,NOLVP,NODEBUG,NOCPD
#use delay(clock=4M)
#include<STDLIB.H>
#use standard_io(A)
#use standard_io(B)
#define PORTB
#DEFINE PORTC
#define PORTA

byte const digit[10]={0xC0,0xF9,0xA4,0xB0,0x99,0x92,0x82,0xF8,0x80,0x90};
 char display[3];
 unsigned int volt1,volt2;
int value;


void main()
{
set_tris_a(0xff);
set_tris_b(0x00);
set_tris_c(0x00);  

   while(TRUE){
   //setup_comparator(NC_NC_NC_NC);
   Setup_adc(ADC_CLOCK_DIV_8);
   setup_adc_ports(AN0);
   set_adc_channel(0);
   setup_vref(FALSE);
      delay_us(10);    
        read_adc(ADC_START_ONLY);
      delay_us(100);
      value=read_adc();
      volt2=(value*500)/1023;

       delay_ms(1);

      volt1=volt2;                
      output_low(PIN_b2);
      display[0]=(volt1/10) + 30;      
      output_c(digit[display[0]]);
      output_high(PIN_b4);
    output_high(PIN_b5);
      delay_ms(10);

       output_low(PIN_b4);
      display[1]=(volt1%10) + 30;      
      output_c(digit[display[1]]);
      output_high(PIN_b2);
     output_high(PIN_b5);
      delay_ms(10);

 	  output_low(PIN_b5);
      display[1]=volt1%10;      
      output_c(digit[display[1]]);
      output_high(PIN_b2);
	  output_high(PIN_b4);
      delay_ms(10);

}
}

Hello,why may I use that +30 in this expression:display[1]=(volt1%10) + 30; ?

mathespbe · Aug 20, 2013

john120 said:
Hello,why may I use that +30 in this expression:display[1]=(volt1%10) + 30; ?

to convert the corresponding ASCII value...

it's actually
display[1]=(volt1%10) + 0x30;
Is it working or not?

Venkadesh_M · Aug 20, 2013

look at the changes

Code C - [expand]
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#include "16f876a.h"
#DEVICE ADC=10
#fuses XT,NOWDT,NOLVP,NODEBUG,NOCPD
#use delay(clock=4M)
#include<STDLIB.H>
#use standard_io(A)
#use standard_io(B)
#define PORTB
#DEFINE PORTC
#define PORTA
 
byte const digit[10]={0xC0,0xF9,0xA4,0xB0,0x99,0x92,0x82,0xF8,0x80,0x90};
 char display[3];
 unsigned int volt1,volt2;
int value;
 
 
void main()
{
set_tris_a(0xff);
set_tris_b(0x00);
set_tris_c(0x00);  
 
   while(TRUE){
   //setup_comparator(NC_NC_NC_NC);
   Setup_adc(ADC_CLOCK_DIV_8);
   setup_adc_ports(AN0);
   set_adc_channel(0);
   setup_vref(FALSE);
      delay_us(10);    
        read_adc(ADC_START_ONLY);
      delay_us(100);
      value=read_adc();
      volt2=(value*500)/1023;
 
       delay_ms(1);
 
      volt1=volt2               
      output_low(PIN_b2);
      display[0]=(volt1%10) ;   
      volt1 = volt1 / 10;   
      output_c(digit[display[0]]);
      output_high(PIN_b4);
    output_high(PIN_b5);
      delay_ms(10);
 
       output_low(PIN_b4);
      display[1]=(volt1%10) ;      
      volt1 = volt1 / 10;   
      output_c(digit[display[1]]);
      output_high(PIN_b2);
     output_high(PIN_b5);
      delay_ms(10);
 
       output_low(PIN_b5);
      display[1]=volt1%10;      
      output_c(digit[display[1]]);
      output_high(PIN_b2);
      output_high(PIN_b4);
      delay_ms(10);
 
}
}

john120 · Aug 20, 2013

mathespbe said:
to convert the corresponding ASCII value...

it's actually
display[1]=(volt1%10) + 0x30;
Is it working or not?

this is not working at all!!

Venkadesh_M · Aug 20, 2013

john120 said:
this is not working at all!!

He said that for LCD, here is no lcd just 7 segment display.. try my program too.....

john120 · Aug 20, 2013

Venkadesh_M said:
He said that for LCD, here is no lcd just 7 segment display.. try my program too.....

The codes are not running.
All of them are not running with 7segment display.

mathespbe · Aug 20, 2013

Frst check the ADC values.. whether it ADC is configured properly or not... Just debug it on proteus and chech the variable values properly...

Venkadesh_M · Aug 20, 2013

john120 said:
The codes are not running.
All of them are not running with 7segment display.

Then it is problem with reading from ADC check on it..

john120 · Aug 20, 2013

Venkadesh_M said:
Then it is problem with reading from ADC check on it..

Hello there,me I already checked you help me to check.

Thanks

jayanth.devarayanadurga · Aug 20, 2013

Zip and post your CCS C code. I will fix it. If you have Proteus file then attach it also.

sahu · Aug 20, 2013

john120 said:

Hello there,can some body help me to know where the error is I am design a 0-30V digital voltmeter but I am always getting 0V on the seven segment display.

Here are the code and the proteus circuit.

PHP:

#include "16f876a.h"
#DEVICE ADC=10
#fuses XT,NOWDT,NOLVP,NODEBUG,NOCPD
#use delay(clock=4M)
#include<STDLIB.H>
#use standard_io(A)
#use standard_io(B)
#define PORTB
#DEFINE PORTC
#define PORTA

byte const digit[10]={0xC0,0xF9,0xA4,0xB0,0x99,0x92,0x82,0xF8,0x80,0x90};
 char display[3];
 unsigned int volt1,volt2;
int value;


void main()
{
set_tris_a(0xff);
set_tris_b(0x00);
set_tris_c(0x00);  

   while(TRUE){
   //setup_comparator(NC_NC_NC_NC);
   Setup_adc(ADC_CLOCK_DIV_8);
   setup_adc_ports(AN0);
   set_adc_channel(0);
   setup_vref(FALSE);
      delay_us(10);    
        read_adc(ADC_START_ONLY);
      delay_us(100);
      value=read_adc();
      volt2=(value*500)/1023;

       delay_ms(1);

      volt2=volt1;                
      output_low(PIN_b2);
      display[0]=volt1/10;      
      output_c(digit[display[0]]);
      output_high(PIN_b4);
    output_high(PIN_b5);
      delay_ms(10);

       output_low(PIN_b4);
      display[1]=volt1%10;      
      output_c(digit[display[1]]);
      output_high(PIN_b2);
     output_high(PIN_b5);
      delay_ms(10);

 	  output_low(PIN_b5);
      display[1]=volt1%10;      
      output_c(digit[display[1]]);
      output_high(PIN_b2);
	  output_high(PIN_b4);
      delay_ms(10);

}
}

Thanks.

Can u post the screenshot image of your schematic asproteus circuit ?

john120 · Aug 21, 2013

sahu said:
Can u post the screenshot image of your schematic asproteus circuit ?

see the schematic here attached and the codes in ccs c

PHP:

#include "16f876a.h"
#DEVICE ADC=10
#fuses XT,NOWDT,NOLVP,NODEBUG,NOCPD
#use delay(clock=4M)
#include<STDLIB.H>
#use standard_io(A)
#use standard_io(B)
#define PORTB
#DEFINE PORTC
#define PORTA
 
byte const digit[10]={0xC0,0xF9,0xA4,0xB0,0x99,0x92,0x82,0xF8,0x80,0x90};
 char display[3];
 unsigned int volt1,volt2;
int value;
 
 
void main()
{
set_tris_a(0xff);
set_tris_b(0x00);
set_tris_c(0x00);  
Setup_adc(ADC_CLOCK_DIV_8);
   setup_adc_ports(AN0);
   set_adc_channel(0);
   setup_vref(FALSE);
 
   while(TRUE){
   //setup_comparator(NC_NC_NC_NC);
   
      delay_us(10);    
        read_adc(ADC_START_ONLY);
      delay_us(100);
      value=read_adc();
      volt2=(value*500)/1023;
 
       delay_ms(1);
 
      volt1=volt2;              
      output_low(PIN_b2);
      display[0]=(volt1%10) ;   
      volt1 = volt1 / 10;   
      output_c(digit[display[0]]);
      output_high(PIN_b4);
    output_high(PIN_b5);
      delay_ms(10);
 
       output_low(PIN_b4);
      display[1]=(volt1%10) ;      
      volt1 = volt1 / 10;   
      output_c(digit[display[1]]);
      output_high(PIN_b2);
     output_high(PIN_b5);
      delay_ms(10);
 
       output_low(PIN_b5);
      display[2]=volt1%100;      
      output_c(digit[display[2]]);
      output_high(PIN_b2);
      output_high(PIN_b4);
      delay_ms(10);
 
}
}

sahu · Aug 27, 2013

john120 said:

see the schematic here attached and the codes in ccs c

PHP:

#include "16f876a.h"
#DEVICE ADC=10
#fuses XT,NOWDT,NOLVP,NODEBUG,NOCPD
#use delay(clock=4M)
#include<STDLIB.H>
#use standard_io(A)
#use standard_io(B)
#define PORTB
#DEFINE PORTC
#define PORTA
 
byte const digit[10]={0xC0,0xF9,0xA4,0xB0,0x99,0x92,0x82,0xF8,0x80,0x90};
 char display[3];
 unsigned int volt1,volt2;
int value;
 
 
void main()
{
set_tris_a(0xff);
set_tris_b(0x00);
set_tris_c(0x00);  
Setup_adc(ADC_CLOCK_DIV_8);
   setup_adc_ports(AN0);
   set_adc_channel(0);
   setup_vref(FALSE);
 
   while(TRUE){
   //setup_comparator(NC_NC_NC_NC);
   
      delay_us(10);    
        read_adc(ADC_START_ONLY);
      delay_us(100);
      value=read_adc();
      volt2=(value*500)/1023;
 
       delay_ms(1);
 
      volt1=volt2;              
      output_low(PIN_b2);
      display[0]=(volt1%10) ;   
      volt1 = volt1 / 10;   
      output_c(digit[display[0]]);
      output_high(PIN_b4);
    output_high(PIN_b5);
      delay_ms(10);
 
       output_low(PIN_b4);
      display[1]=(volt1%10) ;      
      volt1 = volt1 / 10;   
      output_c(digit[display[1]]);
      output_high(PIN_b2);
     output_high(PIN_b5);
      delay_ms(10);
 
       output_low(PIN_b5);
      display[2]=volt1%100;      
      output_c(digit[display[2]]);
      output_high(PIN_b2);
      output_high(PIN_b4);
      delay_ms(10);
 
}
}

dear i say screenshot image of your schematic.
becoz i have not proteus.so i can't open it

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