blinky.c

来自「NXP Cortex-M内核（LPC1700系列）KEIL 调试代码」· C语言 代码 · 共 50 行

/******************************************************************************/
/* BLINKY.C: LED Flasher                                                      */
/******************************************************************************/
/* This file is part of the uVision/ARM development tools.                    */
/* Copyright (c) 2008 Keil Software. All rights reserved.                     */
/* This software may only be used under the terms of a valid, current,        */
/* end user licence from KEIL for a compatible version of KEIL software       */
/* development tools. Nothing else gives you the right to use this software.  */
/******************************************************************************/
                  
#include "LPC17xx.H"                    /* LPC17xx definitions                */

#define LED_NUM     8                   /* Number of user LEDs                */

const int led_mask[] = { 0x01, 0x02, 0x04, 0x08, 0x10, 0x20, 0x40, 0x80 };
volatile unsigned long SysTickCnt;      /* SysTick Counter                    */

void SysTick_Handler (void) {           /* SysTick Interrupt Handler (1ms)    */
  SysTickCnt++;
}

void Delay (unsigned long tick) {       /* Delay Function                     */
  unsigned long systickcnt;

  systickcnt = SysTickCnt;
  while ((SysTickCnt - systickcnt) < tick);
}

int main (void) {                       /* Main Program                       */
  int num = -1; 
  int dir =  1;

  SystemInit();
  SysTick_Config(SystemFrequency/1000 - 1); /* Generate interrupt each 1 ms   */

  GPIO2->FIODIR = 0xFF;                 /* LEDs defined as Output             */

  for (;;) {                            /* Loop forever                       */
    /* Calculate 'num': 0,1,...,LED_NUM-1,LED_NUM-1,...,1,0,0,...             */
    num += dir;
    if (num == LED_NUM) { dir = -1; num =  LED_NUM-1; } 
    else if   (num < 0) { dir =  1; num =  0;         }

    GPIO2->FIOPIN &= ~led_mask[num];
    Delay(500);                         /* Delay 500ms                        */
    GPIO2->FIOPIN |=  led_mask[num];
    Delay(500);                         /* Delay 500ms                        */
  }
}