连云港市城乡建设局网站,行业网站营销特点,网站 建设ppt模板,网站查不到备案需要先编写OneWire模块#xff0c;再在DS18B20模块中调用OneWire模块的函数 先根据原理图做好端口的声明#xff1a;
sbit OneWire_DQ P3^7;接下来像之前一样把时序结构用代码模拟出来#xff1a;
unsigned char OneWire_Init(void)
{unsigned char i;unsigned char Ac… 需要先编写OneWire模块再在DS18B20模块中调用OneWire模块的函数 先根据原理图做好端口的声明
sbit OneWire_DQ P3^7;接下来像之前一样把时序结构用代码模拟出来
unsigned char OneWire_Init(void)
{unsigned char i;unsigned char AckBit;OneWire_DQ 1;OneWire_DQ 0; //总线拉低//延时500usi 227; while (--i);OneWire_DQ 1; //释放总线//延时70usi 29; while (--i);AckBit OneWire_DQ;//延时500usi 227; while (--i);return AckBit;
}void OneWire_SendBit(unsigned char Bit)
{unsigned char i;OneWire_DQ 0; //总线拉低//延时10us后直接读电平i 4; while(--i);OneWire_DQ Bit;//延时50us凑满时间片i 22; while(--i);OneWire_DQ 1;
}unsigned char OneWire_ReceiveBit(void)
{unsigned char i;unsigned char Bit;OneWire_DQ 0;//延时5usi 2; while(--i);OneWire_DQ 1;//延时5usi 2; while(--i);Bit OneWire_DQ;//延时50usi 22; while(--i);return Bit;
}void OneWire_SendByte(unsigned char Byte)
{unsigned char i;for(i 0; i 8; i ) {OneWire_SendBit(Byte (0x01i));}
}unsigned char OneWire_ReceiveByte(void)
{unsigned char i;unsigned char Byte 0x00;for(i 0; i 8; i ) {if(OneWire_ReceiveBit()) {Byte | (0x01i);}}return Byte;
}至此OneWire模块就写好了接下来在DS18B20模块中模拟数据帧 #include REGX52.H
#include OneWire.h#define DS18B20_SKIP_ROM 0xCC
#define DS18B20_CONVERT_T 0x44
#define DS18B20_READ_SCRATCHPAD 0xBEvoid DS18B20_ConvertT(void)
{OneWire_Init();OneWire_SendByte(DS18B20_SKIP_ROM);OneWire_SendByte(DS18B20_CONVERT_T);
}float DS18B20_ReadT(void)
{unsigned char TLSB, TMSB;int temp;float T;OneWire_Init();OneWire_SendByte(DS18B20_SKIP_ROM);OneWire_SendByte(DS18B20_READ_SCRATCHPAD);TLSB OneWire_ReceiveByte();TMSB OneWire_ReceiveByte();temp (TMSB8) | TLSB;T temp / 16.0;return T;
}之后只需要在main中调用即可
#include REGX52.H
#include LCD1602.h
#include DS18B20.hfloat T;void main()
{LCD_Init();LCD_ShowString(1, 1, Temperature!);while(1){DS18B20_ConvertT();T DS18B20_ReadT();if(T 0){LCD_ShowChar(2, 1, -);T -T;}else{LCD_ShowChar(2, 1, );}LCD_ShowNum(2, 2, T, 3);//整数部分LCD_ShowChar(2, 5, .);LCD_ShowNum(2, 6, (unsigned long)(T *10000) % 10000, 4); //小数部分}
}接下来进行一些综合的应用温度报警器按键可调整报警温度的上下限且能用AT24C02记录上下限掉电不丢失这里默认所有温度不会超过DS18B20的芯片范围
#include REGX52.H
#include LCD1602.h
#include DS18B20.h
#include Delay.h
#include AT24C02.h
#include Key.h
#include Timer0.hfloat T, TShow;
char THigh, TLow;
unsigned char KeyNum;void main()
{THigh AT24C02_ReadByte(0);TLow AT24C02_ReadByte(1);//第一次读可能是非法值所以要特判一下if(THigh 125 || TLow - 55 || THigh TLow){THigh 20;TLow 15;}Timer0_Init();LCD_Init();LCD_ShowString(1, 1, T:);LCD_ShowString(2, 1, TH:);LCD_ShowString(2, 9, TL:);LCD_ShowSignedNum(2, 4, THigh, 3);LCD_ShowSignedNum(2, 12, TLow, 3);while(1){KeyNum Key();/*温度读取及显示*/DS18B20_ConvertT();T DS18B20_ReadT();if(T 0){LCD_ShowChar(1, 3, -);TShow -T;}else{LCD_ShowChar(1, 3, );TShow T;}LCD_ShowNum(1, 4, TShow, 3);LCD_ShowChar(1, 7, .);LCD_ShowNum(1, 8, (unsigned long)(TShow * 100)%100, 2);/*阈值判断及显示*/if(KeyNum){if(KeyNum 1) THigh ;if(KeyNum 2) THigh --;if(KeyNum 3) TLow ;if(KeyNum 4) TLow --;LCD_ShowSignedNum(2, 4, THigh, 3);LCD_ShowSignedNum(2, 12, TLow, 3);AT24C02_WriteByte(0, THigh);Delay(5);AT24C02_WriteByte(1, TLow);Delay(5);}if(T THigh) LCD_ShowString(1, 13, OV:H);else if(T TLow) LCD_ShowString(1, 13, OV:L);else LCD_ShowString(1, 13, );}
}void Timer0_Routine() interrupt 1
{static unsigned int T0Count;TL0 0x66; //设置定时初值TH0 0xFC; //设置定时初值T0Count ;if(T0Count 20) //20ms执行一次{T0Count 0;Key_Loop();}
}这还没完在与定时器的结合中定时器的中断会影响OneWire的延时从而影响其中的时序结构进而影响温度实时获取所以在时序结构编写的代码中需要加上屏蔽定时器中断的代码开始时加上EA 0,最后加上EA 1改版后的OneWire模块如下
#include REGX52.Hsbit OneWire_DQ P3^7;unsigned char OneWire_Init(void)
{unsigned char i;unsigned char AckBit;EA 0; //屏蔽中断OneWire_DQ 1;OneWire_DQ 0; //总线拉低//延时500usi 227; while (--i);OneWire_DQ 1; //释放总线//延时70usi 29; while (--i);AckBit OneWire_DQ;//延时500usi 227; while (--i);EA 1;return AckBit;
}void OneWire_SendBit(unsigned char Bit)
{unsigned char i;EA 0; //屏蔽中断OneWire_DQ 0; //总线拉低//延时10us后直接读电平i 4; while(--i);OneWire_DQ Bit;//延时50us凑满时间片i 22; while(--i);OneWire_DQ 1;EA 1;
}unsigned char OneWire_ReceiveBit(void)
{unsigned char i;unsigned char Bit;EA 0; //屏蔽中断OneWire_DQ 0;//延时5usi 2; while(--i);OneWire_DQ 1;//延时5usi 2; while(--i);Bit OneWire_DQ;//延时50usi 22; while(--i);EA 1;return Bit;
}void OneWire_SendByte(unsigned char Byte)
{unsigned char i;for(i 0; i 8; i ) {OneWire_SendBit(Byte (0x01i));}
}unsigned char OneWire_ReceiveByte(void)
{unsigned char i;unsigned char Byte 0x00;for(i 0; i 8; i ) {if(OneWire_ReceiveBit()) {Byte | (0x01i);}}return Byte;
}但是这样虽然能维护好单总线的通信但这样直接屏蔽中断却会影响定时器的计时准确度从而对定时器控制的其他模块造成影响这也就是单总线的一大缺点不过在这个实例中按键的定时器准度要求并不高所以这样控制影响不大
