f_8_18a_ledsw_a.c

来自「* Use 10 MHz crystal frequency. * Use 」· C语言 代码 · 共 34 行

#include "config.h"
#include "serial.c"
#include "serio.c"
#include "delay.h"

// this code illustrates a WRONG way to read a switch
// for press and release.
// Modified from book example so that loop is
// exited after 'i' reaches 5, and message
// is printed. What will happen is that loop is 
// exited on first press, as variable i is incremented
// while switch is held down.
 
void main(void)
{
  int i;

  TRISB = 0xEF;		// set RB4 as output  
  RB4 = 0;		// turn RB4 off
  serial_init(95,1);   // 19200 in HSPLL mode, crystal = 7.3728 MHz 

  pcrlf();printf ("Press switch when ready!");pcrlf();
  i = 0;
  // illustrates wrong way to read a switch for presses
  while(i < 5) {  // exit loop if i >= 5
    if (!RB6) {
      i++;      // wrong -- will increment while switch is pressed
    }
  }
  printf("loop exited, i value is: %d\n",i); pcrlf();
  while(1);  // loop forever
}