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PIC18F1230 ADC with C18 not working

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Flyback

Well-Known Member
Hello,

I have a program which reads the voltage on AN0 using ADC on PIC18F1230.

It then should output the 10 bit conversion result on to 10 LEDs on ports A and B.

However, the ADC always just gives me a reading of zero.

here is my code....

//Program to read Voltage on AN0 using ADC.
//Then output the 10 bit binary number on...
//RA2 RA3 RB0 RB1 RB4 RB5 RA6 RA7 RB2 RB3
//LSB................................MSB

//PIC18F1230
//Compiler = Microchip C18 v3.22
//MPLAB v8.10

#include <p18f1230.h>

#pragma config OSC = INTIO2
#pragma config IESO = OFF
#pragma config PWRT = OFF
#pragma config BOR = OFF
#pragma config WDT = OFF
#pragma config MCLRE = OFF
#pragma config DEBUG = OFF
#pragma config CP0 = OFF
#pragma config CP1 = OFF
#pragma config CPB = OFF
#pragma config CPD = OFF
#pragma config WRT0 = OFF
#pragma config WRT1 = OFF
#pragma config WRTB = OFF
#pragma config WRTC = OFF
#pragma config WRTD = OFF

unsigned char m,n,c,ADRESL_1,ADRESH_1;

void main(void) {

//Set up ports
PORTB = 0x00;
PORTA = 0x00;

//----------------------------------------
//Set up OSCTUNE
//Disable PLL
OSCTUNEbits.PLLEN = 0;

//Set up OSCCON
//4MHZ
OSCCONbits.IRCF2 = 1;
OSCCONbits.IRCF1 = 1;
OSCCONbits.IRCF0 = 0;
//Internal oscillator block
OSCCONbits.SCS1 = 1;
OSCCONbits.SCS0 = 0;
//----------------------------------------

//Set up port direction
//AN0 is analog input (0-5V)
TRISA = 0x01;

TRISB = 0x00;

//DISABLE INTERRUPTS
INTCONbits.GIE = 0;
PIE1bits.ADIE = 0;

//----------------------
//Disable PWM
//$$ PWM time base timer disable $$
PTCON1bits.PTEN = 0;
//SET UP pwm control register 0
//PWM disabled...pins GPIO
PWMCON0bits.PWMEN2 = 0;
PWMCON0bits.PWMEN1 = 0;
PWMCON0bits.PWMEN0 = 0;
//----------------------

//----------------------
//Disable the comparator
CMCONbits.CMEN2 = 0;
CMCONbits.CMEN1 = 0;
CMCONbits.CMEN0 = 0;
CVRCONbits.CVREN = 0;
//----------------------

// ------------------------------------------
// SET-UP ADC:-
//Set-Up ADCON0bits

//disable the special event trigger from PWM
ADCON0bits.SEVTEN = 0;
//ADC MODULE IS DISABLED
ADCON0bits.ADON = 0;

//Set-up ADCON1bits
//+ve ref for AD is AVDD
ADCON1bits.VCFG0 = 0;
//RA6
ADCON1bits.PCFG3 = 0;
//RA4
ADCON1bits.PCFG2 = 0;
//RA1
ADCON1bits.PCFG1 = 0;
//AN0
ADCON1bits.PCFG0 = 1;


//Set-up ADCON2bits
//Right justify
ADCON2bits.ADFM = 1;
//20 TAD = AD acquisition time
ADCON2bits.ACQT2 = 1;
ADCON2bits.ACQT1 = 1;
ADCON2bits.ACQT0 = 1;
//AD conversion clk select bits = Fosc/64
ADCON2bits.ADCS2 = 1;
ADCON2bits.ADCS1 = 1;
ADCON2bits.ADCS0 = 0;
//^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
//Channel 0 = AN0
ADCON0bits.CHS1 = 0;
ADCON0bits.CHS0 = 0;
//ADC MODULE IS ENABLED
ADCON0bits.ADON = 1;



// *** THIS IS A LOOP WHERE AD CONVERSIONS ARE DONE. ***
while(1) {
//Acquisition time wait
for(m=0;m<50;m++) {;}

//Start AD Conversion
ADCON0bits.GO = 1;

while (ADCON0bits.GO) {;}

//Clear AD flag
PIR1bits.ADIF = 0;

//Load up temporary Conversion value holders
ADRESL_1 = ADRESL;
ADRESH_1 = ADRESH;

//zero out 6 MSB's
ADRESH_1 = ADRESH_1 & 0x03;

//Output the 10 bit ADC reading on ports A and B
if (ADRESL_1 & 0x01) {LATAbits.LATA2 = 1;} else {LATAbits.LATA2 = 0;}
if (ADRESL_1 & 0x02) {LATAbits.LATA3 = 1;} else {LATAbits.LATA3 = 0;}
if (ADRESL_1 & 0x04) {LATBbits.LATB0 = 1;} else {LATBbits.LATB0 = 0;}
if (ADRESL_1 & 0x08) {LATBbits.LATB1 = 1;} else {LATBbits.LATB1 = 0;}
if (ADRESL_1 & 0x10) {LATBbits.LATB4 = 1;} else {LATBbits.LATB4 = 0;}
if (ADRESL_1 & 0x20) {LATBbits.LATB5 = 1;} else {LATBbits.LATB5 = 0;}
if (ADRESL_1 & 0x40) {LATAbits.LATA6 = 1;} else {LATAbits.LATA6 = 0;}
if (ADRESL_1 & 0x80) {LATAbits.LATA7 = 1;} else {LATAbits.LATA7 = 0;}
if (ADRESH_1 & 0x01) {LATBbits.LATB2 = 1;} else {LATBbits.LATB2 = 0;}
if (ADRESH_1 & 0x02) {LATBbits.LATB3 = 1;} else {LATBbits.LATB3 = 0;}


}
// *** END OF ADC LOOP ****
return;
}
// *** END OF MAIN ***
// end of code

here is the circuit

i'd be very grateful for any help
 

Pommie

Well-Known Member
Most Helpful Member
Your code is hard to follow at this time of night and without formating.

When I want to read the ADC I use this function,
Code:
int ReadADC(unsigned char Channel){
    ADCON0=(Channel<<2) | 1;
    ADCON2=0b10110101;          //Right justify - Fosc/16
    ADCON0bits.GO=1;            //start conversion
    while(ADCON0bits.GO);       //Wait for it to complete
    return ADRES;
}
It requires that you set tris and adcon1 before you call it.

Mike.
 
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