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PIC18f2431 ADC help

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Cantafford

Member
Hey,

I'm trying to get the ADC of PIC18f2431 to work. I will use it after to control a BLDC motor but since that is a more complex project I have decided to break it into parts and get it done step by step.

Right now I need to learn how to use the ADC properly. To test this I have written a simple program that's supposed to read a voltage from 0-5V, take that value and display it on PORTB. All happens in proteus simulator.



Code:
#include <stdio.h>
#include <stdlib.h>
#include "header.h"


void ConfigureADC()
{
  ADCON0 = 0b00100000; // continuous loop mode, single channel mode
  VCFG1 = 0; // VDD and VSS as ref
  VCFG0 = 0;
  ADCON2 = 0b10001000; // right justified, 2TAD, conversion clock: Fosc/2
  ADCON3 = 0b11000000;  // all triggers disabled(check here the first two bits)
  GASEL1 = 0; // select AN0
  GASEL0 = 0;
  ANSEL0 = 0b00000001;
  ADON = 1; // start ADC
}

void main()
{
OSCCON = 0b01111111;
TRISA = 0b11111111;
TRISB = 0b00000000;
LATB = 0;
ConfigureADC();
while(1)
{
  ADON = 1;
  GODONE=1;//Start conversion
  while(GODONE); //wait for the conversion to finish
  ADON=0;  //switch off adc
  LATB = ADRESL;
}

}
And the header file:
Code:
// PIC18F2431 Configuration Bit Settings

// 'C' source line config statements

#include <xc.h>

// #pragma config statements should precede project file includes.
// Use project enums instead of #define for ON and OFF.

// CONFIG1H
#pragma config OSC = XT         // Oscillator Selection bits (XT oscillator)
#pragma config FCMEN = OFF      // Fail-Safe Clock Monitor Enable bit (Fail-Safe Clock Monitor disabled)
#pragma config IESO = ON        // Internal External Oscillator Switchover bit (Internal External Switchover mode enabled)

// CONFIG2L
#pragma config PWRTEN = OFF     // Power-up Timer Enable bit (PWRT disabled)
#pragma config BOREN = OFF      // Brown-out Reset Enable bits (Brown-out Reset disabled)
// BORV = No Setting

// CONFIG2H
#pragma config WDTEN = OFF      // Watchdog Timer Enable bit (WDT disabled (control is placed on the SWDTEN bit))
#pragma config WDPS = 32768     // Watchdog Timer Postscale Select bits (1:32768)
#pragma config WINEN = OFF      // Watchdog Timer Window Enable bit (WDT window disabled)

// CONFIG3L
#pragma config PWMPIN = OFF     // PWM output pins Reset state control (PWM outputs disabled upon Reset (default))
#pragma config LPOL = HIGH      // Low-Side Transistors Polarity (PWM0, 2, 4 and 6 are active-high)
#pragma config HPOL = HIGH      // High-Side Transistors Polarity (PWM1, 3, 5 and 7 are active-high)
#pragma config T1OSCMX = ON     // Timer1 Oscillator MUX (Low-power Timer1 operation when microcontroller is in Sleep mode)

// CONFIG3H
#pragma config MCLRE = OFF      // MCLR Pin Enable bit (Disabled)

// CONFIG4L
#pragma config STVREN = ON      // Stack Full/Underflow Reset Enable bit (Stack full/underflow will cause Reset)
#pragma config LVP = ON         // Low-Voltage ICSP Enable bit (Low-voltage ICSP enabled)

// CONFIG5L
#pragma config CP0 = OFF        // Code Protection bit (Block 0 (000200-000FFFh) not code-protected)
#pragma config CP1 = OFF        // Code Protection bit (Block 1 (001000-001FFF) not code-protected)
#pragma config CP2 = OFF        // Code Protection bit (Block 2 (002000-002FFFh) not code-protected)
#pragma config CP3 = OFF        // Code Protection bit (Block 3 (003000-003FFFh) not code-protected)

// CONFIG5H
#pragma config CPB = OFF        // Boot Block Code Protection bit (Boot Block (000000-0001FFh) not code-protected)
#pragma config CPD = OFF        // Data EEPROM Code Protection bit (Data EEPROM not code-protected)

// CONFIG6L
#pragma config WRT0 = OFF       // Write Protection bit (Block 0 (000200-000FFFh) not write-protected)
#pragma config WRT1 = OFF       // Write Protection bit (Block 1 (001000-001FFF) not write-protected)
#pragma config WRT2 = OFF       // Write Protection bit (Block 2 (002000-002FFFh) not write-protected)
#pragma config WRT3 = OFF       // Write Protection bit (Block 3 (003000-003FFFh) not write-protected)

// CONFIG6H
#pragma config WRTC = OFF       // Configuration Register Write Protection bit (Configuration registers (300000-3000FFh) not write-protected)
#pragma config WRTB = OFF       // Boot Block Write Protection bit (Boot Block (000000-0001FFh) not write-protected)
#pragma config WRTD = OFF       // Data EEPROM Write Protection bit (Data EEPROM not write-protected)

// CONFIG7L
#pragma config EBTR0 = OFF      // Table Read Protection bit (Block 0 (000200-000FFFh) not protected from table reads executed in other blocks)
#pragma config EBTR1 = OFF      // Table Read Protection bit (Block 1 (001000-001FFF) not protected from table reads executed in other blocks)
#pragma config EBTR2 = OFF      // Table Read Protection bit (Block 2 (002000-002FFFh) not protected from table reads executed in other blocks)
#pragma config EBTR3 = OFF      // Table Read Protection bit (Block 3 (003000-003FFFh) not protected from table reads executed in other blocks)

// CONFIG7H
#pragma config EBTRB = OFF      // Boot Block Table Read Protection bit (Boot Block (000000-0001FFh) not protected from table reads executed in other blocks)

#define _XTAL_FREQ 8000000
I must be doing something wrong because the leds do not light up at all. Please help me correct this. Thanks.
 
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