c - 我无法让 LED 闪烁 6 次，然后终止 C 中的程序

Question

为什么 exit() 不适用于 PIC16f877？

#include <htc.h>
#include <pic16f877.h>
#include <stdlib.h>

#define _XTAL_FREQ 4e6

int main(void){
    int count;
    int max_count = 6;
    TRISD = 0xBF;
    for (count=0; count<max_count; ++count){
        PORTD   = 0x40;
        __delay_ms(500);
        PORTD   = 0x00;
        __delay_ms(500);
    }
    exit(0);
}

错误消息:

Error   [482] lab1_home.obj; 20. symbol "_exit" is defined more than once in "startup.obj"
Error   [482] lab1_home.obj; 20. symbol "_exit" is defined more than once in "startup.obj"

这些代码程序构建成功，但 LED 一直闪烁，是什么原因？

尝试1:

#include <htc.h>
#include <pic16f877.h>

#define _XTAL_FREQ 4e6

void main(void){
    int count;
    int max_count = 6;
    TRISD = 0xBF;
    for (count=0; count<max_count; ++count){
        PORTD   = 0x40;
        __delay_ms(500);
        PORTD   = 0x00;
        __delay_ms(500);
    }
    return;
}

尝试2:

#include <htc.h>
#include <pic16f877.h>
#include <stdio.h>
#include <stdlib.h>

#define _XTAL_FREQ 4e6

int main(void){
    int count = 0;
    int max_count = 6;
    TRISD = 0xBF;
    do {
        count++;
        PORTD   = 0x40;
        __delay_ms(500);
        PORTD   = 0x00;
        __delay_ms(500);
    } while ( count != max_count );
    abort;
}

循环没有退出吗？或者我试图终止程序的方式是错误的？我还考虑了另外一件事...WDT 与这个循环永远重复有什么关系吗？

Answer 1

这段代码成功调用了 sleep 函数并退出了无限循环(感谢@francis):

#include <htc.h>
#include <pic16f877.h>

#define _XTAL_FREQ 4e6
#define SLEEP() asm("sleep")

int main(void){
    int count = 0;
    int max_count = 6;
    TRISD = 0xBF;
    while(count<max_count){
        count++;
        PORTD   = 0x40;
        __delay_ms(500);
        PORTD   = 0x00;
        __delay_ms(500);
    }
    SLEEP();
}