C51源代码－－用按键控制led走马灯实例

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/******************************************************************************
*
* Description : 4 key control led flow
*     key1 -- start
*    key2 -- stop
*    key3 -- up->down
*    key4 -- down->up
*
* Author : liyangth@gmail.com
*
* Date : 2006-12-3
*
******************************************************************************/
#include "reg51.h"
#include "INTRINS.H"

typedef unsigned int uint_t;
typedef unsigned char uchar_t;

uchar_t key(void);
void mydelay(uint_t delay_time);

void main()
{
    uchar_t key_v;
    bit start = 0;
    bit updown = 0;
    uchar_t out_data = 0xfe;

    for(;;){
    key_v = key();

    switch(key_v){
        case 0xfb:{
            start = 1;
            break;
        }
        case 0xf7:{
            start = 0;    /*stop*/
            break;
        }
        case 0xef:{
            updown = 1;
            break;
        }
        case 0xdf:{
            updown = 0;
            break;
        }
    }

    if(start){
        //P1 = 0xf0;
        if(updown)
            out_data = _crol_(out_data,1);
        else
            out_data = _cror_(out_data,1);
        P1 = out_data;
    }
    else
        P1 = 0xff;    /* all down */

    mydelay(1000);
    }
}
/******************************************************************************
*
* Function: uchar_t key(void)
*
* Description: key event
*
* Returns: key_v
*
* Note: respond key value
*
* Add: liy 2006-12-3
*
* Modify:
*
*******************************************************************************/
uchar_t key(void)
{
    uchar_t key_v;
    uchar_t tmp;

    P3 = P3|0x3c;
    key_v = P3;
    if(0xff == (key_v|0xc3))
        return (0);

    mydelay(10);
    key_v = P3;
    if(0xff == (key_v|0xc3))
        return (0);
    else{
        for(;;){
            tmp = P3;
            if(0xff == (tmp|0xc3))
                break;
        }
        return (key_v);
    }
}

/******************************************************************************
*
* Function: void mydelay(uint_t delay_time)
*
* Description: delay delay_time ms
*
* Param:
*
* Returns: void
*
* Note: delay;
*
* add: liyangth@mail.com 12-3
*
* modify:
*
*******************************************************************************/
void mydelay(uint_t delay_time)
{
    uint_t i;
    while(delay_time--){
        for(i = 0; i < 125; i++)
            ;
    }
}