PIC16F877 display the result of ADC on LEDs with C language using MPLAB

Question

I used PIC16F877 and my purpose is to choose CHANNEL 4 to display the analogue input AN4 value on PortD leds. The approximate value is about 1V. I wrote a code and however, no matter how I ran my code, there're not reaction with the GPIO monitor. By the way, do I write ReadADC1() in the while(1){} loop? I tried that, but there's no help. Thanks.

#include <xc.h>
#define LEDs    PORTD   
#include "prologue.c"
unsigned char ReadADC1(void) {
    ADCON0 |= 0b00000010;
    while ( (ADCON0 & 0b00000010) );
    return ADRESH;
}

main ()
{
//  declare variables if any required
    
    TRISA= 0B00100000;   
    ANSEL=0B00010000;
    
    ADCON0 = 0b11010001;
    ADCON1 = 0b10000000; 
    
    LEDs=ReadADC1();

    //*** your code for initialisation if required

    //*** end of your initialisation

    //***  your code for the superloop
    while (1) {

    }
    
    //*** end of the superloop
}

There's no reaction with the GPIO pins monitor. I restarted the IDE many times.

Mike · Accepted Answer · 2022-03-22 11:54:39Z

0

By default all ports are configured as an input. If you want want use a port as an output you had to change the configuration:

TRISD = 0x00;

Another issue: There is no ANSEL register in this controller, you had to do the selection (digital or analog input) with ADCON1register.

edited Mar 22, 2022 at 11:54

answered Mar 22, 2022 at 5:51

Mike

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5 Comments

ke zhang Over a year ago

Hello, ANSEL I used is to select the analogue input. Could you explain the selection with ADCON1 further? Thanks.

Mike Over a year ago

see page 112, ww1.microchip.com/downloads/en/DeviceDoc/30292c.pdf

ke zhang Over a year ago

I've checked that. My code ADCON1 = 0b10000000 has set the analogue input.

Mike Over a year ago

Thats right, You don't need ANSEL

Dan1138 Over a year ago

This question was asked on the Microchip forum here, as the OP never confirmed they were actually using the ancient PIC16F877 controller the thread has gone dormant.

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