[PIC] Woking with internal ADC of PIC16f877a

[IKPE80]

Can any one help me on this. I am working on voltmeter using the adc of pic6f877a with lcd , my code works perfect on proteus but when i implement it, it won't respond fine. At times it display, at times it don't. Pls i need help.

 

[amayilsamy]

Check the delay for display LCD, the delay might be low or high in your code. In proteus delay not a problem. What you seen in the display.

 

[ud23]

Can any one help me on this. I am working on voltmeter using the adc of pic6f877a with lcd , my code works perfect on proteus but when i implement it, it won't respond fine. At times it display, at times it don't. Pls i need help.

No one can help you better with out your code and hardware connection.Post the code and circuit.

 

[IKPE80]

No one can help you better with out your code and hardware connection.Post the code and circuit.

I am using mickroC compiler so my code and the proteus design are below

                              // LCD module connections
sbit LCD_RS at RB4_bit;
sbit LCD_EN at RB5_bit;
sbit LCD_D4 at RB0_bit;
sbit LCD_D5 at RB1_bit;
sbit LCD_D6 at RB2_bit;
sbit LCD_D7 at RB3_bit;

sbit LCD_RS_Direction at TRISB4_bit;
sbit LCD_EN_Direction at TRISB5_bit;
sbit LCD_D4_Direction at TRISB0_bit;
sbit LCD_D5_Direction at TRISB1_bit;
sbit LCD_D6_Direction at TRISB2_bit;
sbit LCD_D7_Direction at TRISB3_bit;
// End LCD module connections
//char look(int a);
void main()
{

  int v;
  char volt[5];
  ADC_INIT();
  Lcd_Init();
  Lcd_Cmd(_LCD_CLEAR);
  Lcd_Cmd(_LCD_CURSOR_OFF);

  do
  {
       v = ADC_Read(2);
       v = v*0.2246;

       IntToStr(v,volt);
       LTrim(volt);
       Lcd_Out(1,1,"Voltage = ");
       Lcd_Out(1,11,volt);
       Lcd_Out(1,16,"V");
  } while(1);

}

 

[IKPE80]

Check the delay for display LCD, the delay might be low or high in your code. In proteus delay not a problem. What you seen in the display.

Pls I am using MickroC compiler how do i check the LCD delay of their library because I am using their own library not my own function for LCD.

 

[ud23]

if you have same connections in real hardware as you posted in the simulation then you need some pot at pin 3 for contrast and VCC for pin 2in the real hardware.

What is your real hardware output you getting?

 

[milan.rajik]

Fixed code.

---

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sbit LCD_RS at RB4_bit;
sbit LCD_EN at RB5_bit;
sbit LCD_D4 at RB0_bit;
sbit LCD_D5 at RB1_bit;
sbit LCD_D6 at RB2_bit;
sbit LCD_D7 at RB3_bit;
 
sbit LCD_RS_Direction at TRISB4_bit;
sbit LCD_EN_Direction at TRISB5_bit;
sbit LCD_D4_Direction at TRISB0_bit;
sbit LCD_D5_Direction at TRISB1_bit;
sbit LCD_D6_Direction at TRISB2_bit;
sbit LCD_D7_Direction at TRISB3_bit;
 
int v;
char volt[17];
 
void main() {
 
  CMCON = 0x07;
  ADCON0 = 0x40;
  ADCON1 = 0b10000010;
  CVRCON = 0x00;
 
  TRISA = 0x02;
  PORTA = 0x00;
 
  Lcd_Init();
  Lcd_Cmd(_LCD_CURSOR_OFF);
  Lcd_Cmd(_LCD_CLEAR);
  Lcd_Out(1,1,"Voltage = "); 
 
  do {
       v = ADC_Read(2) * 0.2246;       
       IntToStr(v, volt);
       LTrim(volt);       
       Lcd_Out(1,11,volt);
       Lcd_Out(1,16,"V");
  } while(1);
}

---

 

[IKPE80]

Fixed code.

---

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sbit LCD_RS at RB4_bit;
sbit LCD_EN at RB5_bit;
sbit LCD_D4 at RB0_bit;
sbit LCD_D5 at RB1_bit;
sbit LCD_D6 at RB2_bit;
sbit LCD_D7 at RB3_bit;
 
sbit LCD_RS_Direction at TRISB4_bit;
sbit LCD_EN_Direction at TRISB5_bit;
sbit LCD_D4_Direction at TRISB0_bit;
sbit LCD_D5_Direction at TRISB1_bit;
sbit LCD_D6_Direction at TRISB2_bit;
sbit LCD_D7_Direction at TRISB3_bit;
 
int v;
char volt[17];
 
void main() {
 
  CMCON = 0x07;
  ADCON0 = 0x40;
  ADCON1 = 0b10000010;
  CVRCON = 0x00;
 
  TRISA = 0x02;
  PORTA = 0x00;
 
  Lcd_Init();
  Lcd_Cmd(_LCD_CURSOR_OFF);
  Lcd_Cmd(_LCD_CLEAR);
  Lcd_Out(1,1,"Voltage = "); 
 
  do {
       v = ADC_Read(2) * 0.2246;       
       IntToStr(v, volt);
       LTrim(volt);       
       Lcd_Out(1,11,volt);
       Lcd_Out(1,16,"V");
  } while(1);
}

---

Thanks, the fixed code worked, but i have to change the TRISA = 0x02 to TRISA = 0xff. Please what does CMCON and CVRCON mean?

 

[milan.rajik]

CMCON = Comparator Control
CVRCON = Comparator Voltage Reference Control

 

[IKPE80]

CMCON = Comparator Control
CVRCON = Comparator Voltage Reference Control

Thank you very much.