Program exits endless loop (PIC microcontroller)?

Question

I wrote a program for the PIC 16f690 microcontroller after noticing my programs seemed to be exiting an endless loop.

There are LEDs on pins 3,4,5 of PORTC.

#include <xc.h>
#define _XTAL_FREQ 4000000

void main(void) {

    TRISC = 0x00;
    PORTC = 0b00111000;

    while (1)
    {
        __delay_ms(1000);
        PORTC = 0x00;
    }
}

As far as I understand, the LEDS should be on for ~1sec, and then be off forever. Instead they keep blinking every second.

I wrote this in MPLABX and programmed using PICkit3 and C8 compiler.

If you don't want them to blink, try doing that without loop and feed us back — chouaib, Jul 30 '14 at 23:48

score 6 · Accepted Answer · answered Jul 30 '14 at 23:54

6

You are likely being bitten by the watchdog. Disable the watchdog for your tests or clear it before it reset the MCU.

answered Jul 30 '14 at 23:54

ouah

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I wanted to say thanks, since that fixed my problem, but this comment section doesn't want me to. I'm new to SO, so for future reference should I avoid making a comment that says, "this worked" and just click the checkmark? – user3893595 Jul 31 '14 at 00:42
@user3893595 You are welcome! My opinion is it's up to you. I let you read http://meta.stackexchange.com/questions/126180/is-it-acceptable-to-write-a-thank-you-in-a-comment and http://meta.stackexchange.com/questions/145551/acknowledging-thank-you-comments – ouah Jul 31 '14 at 00:47

score 0 · Answer 2 · edited Jul 17 '17 at 07:22

I had the same issue but in place of leds, I was using serial communications. while(1) was not really a loop forever and execute the stuff between brackets.

As soon as I disabled the watchdog, only the stuff inside the brackets was called after the first iteration.

#pragma config WDTE = OFF        // Watchdog Timer Enable (WDT enabled)

I was also observing trash after every uart packet and that went away with the watchdog disabled.

FYI pic 16f1708.

This caused some erratic behavior since the uart initialization functions, IO setup, and oscillator divider were called every loop iteration.

Program exits endless loop (PIC microcontroller)?

2 Answers2