怎么让单片机计时器改成倒计时,可以通过独立按键设置倒计时(用的是普中板)

ID:1094758 · 发表于 2023-9-28 14:49

#include <reg52.h>

typedef unsigned int u16;
typedef unsigned char u8;

#define KEY_PRESS1 1
#define KEY_PRESS2 2
#define KEY_PRESS3 3
#define KEY_PRESS4 4
#define KEY_UNPRESS 0

#define SMG_SORT P0
#define LED_SORT P2

void delay_10us(u16 ten_us)
{
   while(ten_us--);
}

u8 NUM_SMG[] = {0x3f,0x06,0x5b,0x4f,0x66,0x6d,0x7d,0x07,
            0x7f,0x6f,0x40};
u8 SELECT_SMG[] = {0x00,0x04,0x08,0x0c,0x10,0x14,0x18,0x1c};

void time0_init()
{
TMOD |= 0x01;  //设置工作方式；定时器0的工作模式1
TH0 = 0xFC;
TL0 = 0x18;
EA = 1;       //中断总开关
ET0 = 1; //定时器0允许位
TR0 = 1; //打开定时器0
}

sbit LED1 = P2^0;
static u16 n = 0;

sbit KEY1 = P3^1;
sbit KEY2 = P3^0;
sbit KEY3 = P3^2;
sbit KEY4 = P3^3;

static u8 hour = 0;
static u8 min = 0;
static u8 time = 0;
static u8 scan_state = 0;

void Show_time(u8 ti, u8 loc)
{
u8 a = ti/10;
u8 b = ti%10;
SMG_SORT = NUM_SMG;
P2 = SELECT_SMG[loc];
delay_10us(100);

SMG_SORT = NUM_SMG[a];
P2 = SELECT_SMG[loc+1];
delay_10us(100);
}

void show_line()
{
SMG_SORT = 0x40;
P2 = SELECT_SMG[2];
delay_10us(100);

SMG_SORT = 0x40;
P2 = SELECT_SMG[5];
delay_10us(100);
}

u8 key_scan() // 返回按键的状态  0  1  2  3  4
{
      if(scan_state==0&KEY1==0||KEY2==0||KEY3==0||KEY4==0)
      {
      delay_10us(1000);
      scan_state = 1;
      if(KEY1==0 )return 1;
      if(KEY2==0 )return 1;
      if(KEY3==0 )return 1;
      if(KEY4==0 )return 1;
      }
      else if(KEY1==1&KEY2==1&KEY3==1&KEY4==1)
      {
      scan_state=0;
      }
      return 1;
}

void time_ADD()
{
if(KEY4==0)
{

      delay_10us(20);
      while(!KEY4);
         Show_time();
         time++;
         if(time>59)
         {
            min++;
            time = 0;
            if(min>59)
            {
                  hour++;
                  min = 0;
            }
         }
}
}
void time_SUB()
{
if(KEY3==0)
{
      delay_10us(20);
      while(!KEY3);       //判断按键是否松手
         Show_time();
         if(min>0||time>0)
         {
            time--;
            if(time==0)
            {
                  min--;
                  time=59;
            }
         }
}
}

void main()
{
time0_init();
LED1 =0;
while(1)
{
      Show_time(time,0);
      Show_time(min,3);
      Show_time(hour,6);
      show_line();

}
}

void time0() interrupt 1
{
//注：每次进入中断意味着定时/和计数器已经溢出，若要继续重复工作，需要重新赋值
TH0 = 0xFC;
TL0 = 0x18;
n++;
if(n==1000)
{
      n = 0;
      time += 1;
      if(time >= 59)
      {
         time = 0;
         min +=1;
         if(min == 60)
         {
            min = 0;
            hour += 1;
            if(hour == 24)
            {
                  hour = 0;
            }
         }
      }
}
}

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