接下来我们将任务分块：

1. 按键控制单元 设定按键 S7 为出水控制按键，当 S7 按下后，售水机持续出水（继电器接通，指示 灯 L10 点亮）。设定按键 S6 为停水控制按键，当 S6 按下后，停止出水（继电器断开， 指示灯 L10 熄灭）。

# include "reg52.h" 
# include "iic.h"
# include "onewire.h"     
# include "ds1302.h"      
# include "intrins.h"		 //S7°´Ï£¬L10µãÁÁ¡£S6°´Ï£¬L10ϨÃð
sbit S7=P3^0;
sbit S6=P3^1;
sbit S5=P3^2;
sbit S4=P3^3;//ledµÆ
sbit L1=P0^0;
sbit L2=P0^1;
sbit L3=P0^2;
sbit L4=P0^3;
sbit L5=P0^4;
sbit L6=P0^5;void SelectHC573(unsigned char channel)
{switch(channel){case 4:P2 = (P2 & 0X1f) | 0x80;break;case 5:P2 = (P2 & 0X1f) | 0xa0;break;case 6:P2 = (P2 & 0X1f) | 0xc0;break;case 7:P2 = (P2 & 0X1f) | 0xe0;break;case 0:P2 = (P2 & 0X1f) | 0x00;break;}
}void Delay(unsigned int t)
{while(t--);
}void Scankey()
{SelectHC573(5);if(S7 == 0){Delay(500);if(S7 == 0){P0 = 0xff;}}if(S6 == 0){Delay(500);if(S6 == 0){P0 = 0x00;}}SelectHC573(0);
}void main()
{while(1){Scankey();}
}

任务： 通过 4 位数码管 DS1 显示费率，单位为元/升，保留 2 位有效数字； 通过 4 位数码管 DS2 显示当前出水总量（出水时，单位为升）和总价（停止时，单 位为元）：按下出水按键 S7 后，清除数码管 DS2 显示数据，数码管 DS2 实时显示出水 量(保留两位有效数字)，在出水状态下，再次按下 S7，不会影响出水状态，直到按下停 止按键 S6 为止；按下停止出水按键 S6 后，数码管 DS2 显示总价（保留两位有效数字）。

 这个也就是数码管显示，我们也是可以分来进行

当按下S7时：

当按下S6时：

系统说明：

1. 假定水价为 0.5 元/升，出水速度为 100 毫升/秒； 2. 一次出水总量达到 99.99L 时，继电器自动断开，数码管显示 DS2 显示价格。

我们先来实现出水量，通过定时器来计数出水量，每100ml/s

# include "reg52.h"
# include "Scankey.h"
# include "iic.h"
# include "onewire.h"     
# include "ds1302.h"      
# include "intrins.h"		sbit S7=P3^0;
sbit S6=P3^1;
sbit S5=P3^2;
sbit S4=P3^3;/* ±äÁ¿ÉùÃ÷Çø */
unsigned char code SMG_duanma[18]={0xc0,0xf9,0xa4,0xb0,0x99,0x92,0x82,0xf8,0x80,0x90,0x88,0x80,0xc6,0xc0,0x86,0x8e,0xbf,0x7f};unsigned int count = 0;
unsigned int water_value = 0; //³öË®Á¿		 
unsigned int water_money = 0;
unsigned int water_count = 0;/* ³öË®Á¿¼ÆËã */void Init_Timer0() //¶¨Ê±50ms
{TMOD = 0x01;                    TH0 = (65536 - 50000) / 256;      TL0 = (65536 - 50000) % 256;ET0 = 1;                      EA = 1;                             TR0 = 1;                       
}void SeviceTimer0() interrupt 1
{//50ms £¬100ms¾Í¿ÉÒÔÔÚ×îºóTH0 = (65536 - 50000) / 256;TL0 = (65536 - 50000) % 256;count++;water_value = count/2;}void DelaySMG(unsigned int t)
{while(t--);
}/*************ÊýÂë¹Ü***********/
void DisplaySMG(unsigned char dat,unsigned int pos) //posλÖã¬datÄÚÈÝ
{SelectHC573(7);P0 = 0xff;SelectHC573(6);P0 = (0x01 << pos);SelectHC573(7);P0 = dat;SelectHC573(0);	}/******ÏÂÃæÉè¼ÆÁ½¸öÊýÂë¹ÜµÄÖµ£¬ÎÒÃÇ°ÑÁ½±ß·Ö¿ª¼ÆË㣬ÎÒÃÇÏÈ¿´DS2   */void ShowSMG_DS2_Water()
{if(water_value<10){DisplaySMG(SMG_duanma[water_value],7);DelaySMG(300);}else if(water_value>=10 && water_value <100){DisplaySMG(SMG_duanma[water_value%10],7);DelaySMG(300);DisplaySMG(SMG_duanma[water_value/10],6);DelaySMG(300);}else if(water_value>=100 && water_value <1000){DisplaySMG(SMG_duanma[water_value%10],7);DelaySMG(300);DisplaySMG(SMG_duanma[water_value/10%10],6);DelaySMG(300);DisplaySMG(SMG_duanma[water_value/100],5);DelaySMG(300);}else if(water_value >= 1000){DisplaySMG(SMG_duanma[water_value%10],7);DelaySMG(300);DisplaySMG(SMG_duanma[water_value/10%10],6);DelaySMG(300);DisplaySMG(SMG_duanma[water_value/100%10],5);DelaySMG(300);DisplaySMG(SMG_duanma[water_value/1000],4);DelaySMG(300);}
}void main()
{Init_Timer0();Scankey();while(1){ShowSMG_DS2_Water();}
}