pic16f877a adc mesure ac voltage

[jouyorin]

hello
i'm using pic16f877a to mesure ac voltage this is my circuit: but it can read only values between 80v to 240 v..however im doing the same circuit with arduio and it works ! i guess the problem is in adc gonfiguration of pic16f877a, but i can't solve it cauz this pic don't hav ANSEL and ANSELH ..i already try to modifie ADCON1 but no result..please can someone help me! thnx in advance.

cofig I/O pic16f877a:
TRISA = 0xFF;
PORTA = 0x00;
TRISB = 0x00;
PORTB = 0x00;
TRISC = 0x80;
PORTC = 0x00;
ADCON1 = 0x80;

 

[wp100]

Hi,

You need to show your full adc and config program code, those few lines insufficient.

 

[jouyorin]

this is my program i didn't understand what i have exactely to modifie:

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Code C - [expand]
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// LCD module connections
sbit LCD_RS at RC1_bit;
sbit LCD_EN at RC2_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_D3 at RB4_bit;
sbit LCD_D2 at RB5_bit;
sbit LCD_D1 at RB6_bit;
sbit LCD_D0 at RB7_bit;
 
sbit LCD_RS_Direction at TRISC1_bit;
sbit LCD_EN_Direction at TRISC2_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;
sbit LCD_D3_Direction at TRISB4_bit;
sbit LCD_D2_Direction at TRISB5_bit;
sbit LCD_D1_Direction at TRISB6_bit;
sbit LCD_D0_Direction at TRISB7_bit;
// End LCD module connections
char display[16]="";float U;
  unsigned int vs;
  unsigned char text0[4] ;
  char uart_rd;
 
int U0 = 0;
//Programme principal :
        Adc_Init() ;
 
void main() {
Uart1_Init (9600);
 {  char UART1_Read(U);
     {
       Delay_ms(100);
        TRISA = 0xFF;
      PORTA = 0x00;
      TRISB = 0x00;
      PORTB = 0x00;
      TRISC = 0x80;
      PORTC = 0x00;
      ADCON1 = 0x80;               // Configure all other AN pins as digital I/O               // Pins RC7 and RC6 are configured as outputs
 
                      // PORTB is configured as an output
       lcd_init();
       lcd_cmd(_lcd_clear);
       lcd_cmd(_LCD_CURSOR_OFF);
     }
 
 
{
         while(1)
         {
            U0 = Adc_Read(0);
            vs=U0*0.0048;    // Lu canal AN0 et enregistrez la valeur dans la variable temp0
            U =vs*80.0519;
            ByteToStr(U, text0);
            floattostr(U,display);
            lcd_out_cp(display);
            lcd_chr(1,14,223); //print at pos(row=1,col=13) "°" =223 =0xdf
            lcd_out_cp("Volt");
 
            UART1_Write_Text("La tension Mch1 est : ");
            UART1_Write_Text(text0); // Envoyé à l'uart
            UART1_Write_Text(" Volt");
 
            Uart1_Write('\r'); //
            delay_ms(500);
          }
          }
}
}

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[justeen]

i want to make a project to measure negative and positive dc voltage (-50v to 50v), you can give me a project suggest! thanks.