原创 MSP430F2618基础实验2（按键控制LED灯）

工程文件：https://static.assets-stash.eet-china.com/album/old-resources/2009/2/10/4666aaf6-1f39-433d-aeb1-c2ed95df7442.rar

原理图：

#include  <msp430x26x.h>

#define       KEY_LEFT        P4IN&0x040
#define       KEY_RIGHT       P4IN&0x080
#define       KEY_UP          P4IN&0x020
#define       KEY_DOWN        P4IN&0x010

#define       LEFT        1
#define       RIGHT       2
#define       UP          3
#define       DOWN        4

unsigned char ScanKey(void)
{
    if(!(KEY_LEFT))
    {
      while(!(KEY_LEFT));
      return LEFT;
    }
    else if(!(KEY_RIGHT))
    {
      while(!(KEY_RIGHT));
      return RIGHT;
    }
    else if(!(KEY_DOWN))
    {
      while(!(KEY_DOWN));
      return DOWN;
    }
    else if(!(KEY_UP))
    {
      while(!(KEY_UP));
      return UP;
    }
    else return 0;
}

void main(void)
{
  WDTCTL = WDTPW + WDTHOLD;                 // Stop watchdog timer
  P4DIR |= 0x0f;                            // Set P4.0~P4.3 to output direction
  P4DIR &= ~0xf0;
  P4OUT |=0x0f;

  for (;;)
  {
    volatile unsigned int i;
    unsigned char key_value;
      key_value=ScanKey();
      P4OUT &=~(0x10>>key_value);
      i = 10000;                              // Delay
      do (i--);
      while (i != 0);
    P4OUT |=0x0f;
  }
}