跪求指导！ds18b20读不到温度，用示波器打过，读那一段有问

只看该作者 · 2013-6-20 20:39

本帖最后由 paulful 于 2013-6-20 21:00 编辑

//用的是pic18f258，4M晶振，仿真和固化时候， Temperature[0]都是读出oxffff，一直找不到问题出在哪里

#include"pic18.h"
//-------------------------------------------------端口位定义--------------------------------------------
#define BIT0 0x01

#define DOUT       TRISA&=~BIT0 //RAO输出
#define DIN          TRISA|=BIT0    //RAO输入
#define DOUT_H PORTA|=BIT0 //RA0输出为高
#define DOUT_L    PORTA&=~BIT0 //RA0输出为低

#define DE RA5 //接MAX485 DE脚，为1时发送，为0时接收

//-------------------------------------------------------------------------

unsigned int Temperature[6],Btem,Ttem,j;
//float T;
unsigned char Atemp;

//-----------------------------------------系统初始化-----------------------------------
void initial()
{
INTCON=0X00;
ADCON1=0X07;       //配置portA口为I/O口

PIE1=0;
PIE2=0;
PIE3=0;
}

//.................................................串口初始化...................................................
void USARTini()       //定时器及USART的初始化
{

      RCSTA = 0x80; //允许串行口工作使能
      TXSTA = 0x04; //选择异步通信高速方式传输8位
      TRISC=TRISC|0X80;
      TRISC=TRISC&0XBF; //配置RC7为输入，RC6为输出
      TRISA=TRISA&0XDE; //配置RA5为0输出,RA0为输出
      TRISB=TRISB&0XEF; //配置RB4为0输出
      SPBRG = 25;          // 9600 = 4M / ( 16 * ( 25+1 ) ) HIGH
      PIR1=0x00;          //清中断标志
      //PIE1=PIE1|0X20;
      // RCIP=0;
            DE=1;                   //MAX485处于发送
      TXEN=1;                // 允许发送

}

//.................................................延时函数........................................
/*void delay_nus(unsigned int n)
{
  char i;
  for(i=0;i<n;i++);

}*/

void delay_nus(unsigned int n)
{while(--n);}

void delayn() //6us
{
  asm("nop");
}

//N ms延时函数
void delay_nms(unsigned int n)
{
   unsigned int a=0;
   unsigned int b=0;
   for (a=0;a<n;a++)
   for (b=0;b<655;b++);
}

/*------------------------------------------------Temprature------------------------------------------*/

//................................................................初始化DS18B20..........................................
void InitDS18B20()
{
      DOUT;
      DOUT_H;                                  // 释放（拉高）总线
      DOUT_L;                         // 占领（拉低）总线
      delay_nus(60);                               // 480us-960us ,786us
      DOUT_H;                         // 释放总线
      DIN;                   //切换到输入

      delay_nus(22);                //10,136US;40,526us 25,331us          延时后被拉高  //跳过了低电平，等待被拉高

      DOUT;          //输出
      DOUT_H;                                  // 释放（拉高）总线
   delay_nus(30);          //396us

}

//字写
void WriteDS18B20(unsigned int x)
{
      unsigned int a;
      for(a=0;a<8;a++)
      {
         DOUT;
            DOUT_L;                                     //拉低总线1-15us ,大于1us
            asm("nop");
         asm("nop");


            if( x & (1<<a) )
            {
                     DOUT_H;                               //置高总线
            }
            else
            {
                     DOUT_L;                               //拉低总线
            }
            delay_nus(6);             // 大于60us //1,19us;2,32us;3,45us;4,58us;8,110US
         DOUT_H;                                  // 完毕后释放（拉高）总线

      }
}

unsigned int ReadDS18B20()
{
      unsigned int Temp,n;
   Temp=0;
      for(n=0;n<8;n++)
      {

DOUT_H; // 置高总线  输入为1
      asm("nop");  asm("nop");
         DOUT_L;

      DOUT_H;
asm("nop");asm("nop");asm("nop");
         DIN;
         asm("nop");
         if( PORTA& 0x01 )
               {

                     Temp |= (1<<n);
            }
            else
            {
                     Temp &= ~(1<<n);
            }
         delay_nus(6);                         //1,19us;2,32us;3,45us ,6,89us
      DOUT;
   DOUT_H;
      }
      return(Temp);
}

void Get_Data()
{
   unsigned int temh,teml;
      InitDS18B20();

      WriteDS18B20(0xCC);                               //跳过ROM
      WriteDS18B20(0x44);                               // 发出转换命
   delay_nms(150);       // 900多毫秒
         InitDS18B20();
         WriteDS18B20(0xCC);                //跳过ROM
      WriteDS18B20(0xBE);                      //读18B20温度
delay_nus(60);                         // 700多微秒
            teml = ReadDS18B20();
            temh = ReadDS18B20();
         Temperature[0] = (temh << 8) + teml;

}

void DEAL()
{

  Temperature[1]=Temperature[0]/16;

}

void SENDDATA()
{
   RB4=0;
   TXREG=(char)Temperature[1];

}

//..............................................................主程序.................................................................

main()
{
initial();
USARTini();
asm("nop");
asm("nop");

while(1)
      {

      Get_Data();
   // delay_nus(6);
   DEAL();
   SENDDATA();

      }
}

只看该作者 · 2013-6-20 20:45

我用的是PIC18F258，用的是RAO口，18b20的上拉电阻是4.7k。弄了半个月都没弄好，很急了，心里好郁闷，求指导。图中电容没有悍，也悍过100p过。

1万 · 2013-6-20 22:46

我给你上一个avr写的18b20读取函数吧

1万 · 2013-6-20 22:47

#include "../../include.h"

#if EXTERNAL_MODULE_SD2405_MODE != 0

void IIC_Init(void)
{
SETBIT(IIC_DDR, IIC_SCL);       // Set SCL to output
SETBIT(IIC_DDR, IIC_SDA);    // Set SDA to output
SETBIT(IIC_PORT, IIC_SCL);      // Set SCL high
SETBIT(IIC_PORT, IIC_SDA); // Set SDA high
}

void IIC_Delay(void)
{
TARGET_Delayus(1, 0);
}

void IIC_Start( void )
{
SETBIT(IIC_PORT, IIC_SCL);       // Set SCL High
SETBIT(IIC_PORT, IIC_SDA);       // Set SDA High
SETBIT(IIC_DDR, IIC_SDA);       // Set SDA to output
CLRBIT(IIC_PORT, IIC_SDA);      // Clear SDA
}

void IIC_Stop( void )
{
SETBIT(IIC_DDR, IIC_SDA);       // Set SDA to output
CLRBIT(IIC_PORT, IIC_SDA);      // Clear SDA
CLRBIT(IIC_PORT, IIC_SCL);      // Clear SCL
SETBIT(IIC_PORT, IIC_SCL);      // Set SCL High
IIC_Delay();
SETBIT(IIC_PORT, IIC_SDA);    // Set SDA High
}

void IIC_Clock( void )
{
SETBIT(IIC_PORT, IIC_SCL);       // Set SCL high
IIC_Delay();
CLRBIT(IIC_PORT, IIC_SCL);      // Set SCL low
}

uint8 IIC_Ackn( void )
{
uint8 Ackn = 0;                   // Temp RAM for Ackn flag
CLRBIT(IIC_PORT, IIC_SCL);
CLRBIT(IIC_DDR, IIC_SDA);                // Set SDA to input
SETBIT(IIC_PORT, IIC_SCL);            // Clock the ACK bit
if (CHKBIT(IIC_PIN, IIC_SDA)) Ackn = 1; // Check the ACK bit on SDA
CLRBIT(IIC_PORT, IIC_SCL);                      // Clear the clock
return Ackn;       // Return our ACK bit
}

void IIC_WriteControl( uint8 u8_HardwareAddress, uint8 u8_ReadOrWrite )
{
// *** Send the I2C device Control code *** //
CLRBIT(IIC_PORT, IIC_SCL);                         // Clear SCL clock
if( (u8_HardwareAddress & 0x80) == 0x80) SETBIT(IIC_PORT, IIC_SDA);    // Set I2C SDA PIN
else CLRBIT(IIC_PORT, IIC_SDA);             // Clear I2C SDA PIN
IIC_Clock();                           // Clock I2C bit
if( (u8_HardwareAddress & 0x40) == 0x40) SETBIT(IIC_PORT, IIC_SDA);    // Set I2C SDA PIN
else CLRBIT(IIC_PORT, IIC_SDA);             // Clear I2C SDA PIN
IIC_Clock();                           // Clock I2C bit
if( (u8_HardwareAddress & 0x20) == 0x20) SETBIT(IIC_PORT, IIC_SDA);    // Set I2C SDA PIN
else CLRBIT(IIC_PORT, IIC_SDA);                   // Clear I2C SDA PIN
IIC_Clock();                           // Clock I2C bit
if( (u8_HardwareAddress & 0x10) == 0x10) SETBIT(IIC_PORT, IIC_SDA);    // Set I2C SDA PIN
else CLRBIT(IIC_PORT, IIC_SDA);               // Clear I2C SDA PIN
IIC_Clock();                           // Clock I2C bit
// *** Send the I2C Control byte chip selects bits *** //
if( (u8_HardwareAddress & 0x08) == 0x08) SETBIT(IIC_PORT, IIC_SDA);    // Set I2C SDA PIN
else CLRBIT(IIC_PORT, IIC_SDA);             // Clear I2C SDA PIN
IIC_Clock();                           // Clock I2C bit
if( (u8_HardwareAddress & 0x04) == 0x04) SETBIT(IIC_PORT, IIC_SDA);    // Set I2C SDA PIN
else CLRBIT(IIC_PORT, IIC_SDA);             // Clear I2C SDA PIN
IIC_Clock();                           // Clock I2C bit
if( (u8_HardwareAddress & 0x02) == 0x02) SETBIT(IIC_PORT, IIC_SDA);    // Set I2C SDA PIN
else CLRBIT(IIC_PORT, IIC_SDA);                // Clear I2C SDA PIN
IIC_Clock();                           // Clock I2C bit
// *** Set or Clear the read / write bit for I2C control *** //
if(u8_ReadOrWrite) SETBIT(IIC_PORT, IIC_SDA);            // Set I2C SDA PIN
else CLRBIT(IIC_PORT, IIC_SDA);       // Clear I2C SDA PIN
IIC_Clock();                           // Clock I2C bit
IIC_Ackn();       // Check for acknowledge from I2C device
}

void IIC_WriteByte( uint8 u8_Data )
{
uint8 i;
SETBIT(IIC_DDR, IIC_SDA); // Set SDA to output
CLRBIT(IIC_PORT, IIC_SCL);
for(i = 0; i < 8; i++) // Loop for our 8 bits
{
// Set or Clear SDA pin
if((u8_Data & 0x80) == 0x80) SETBIT(IIC_PORT, IIC_SDA); // Set I2C SDA PIN
else CLRBIT(IIC_PORT, IIC_SDA); // Clear I2C SDA PIN
SETBIT(IIC_PORT, IIC_SCL);                      // Set SCL High, Clock data
u8_Data = u8_Data << 1; // Shift data in buffer right one
CLRBIT(IIC_PORT, IIC_SCL);                      // Clear SCL
}
IIC_Ackn();             // Check for acknowledge from I2C device
}

uint8 IIC_ReadByte(void)
{
uint8 i,buff = 0;
for (i = 0; i < 8; i++)
{
buff = buff << 1;
CLRBIT(IIC_DDR, IIC_SDA);    // Set SDA to input
SETBIT(IIC_PORT, IIC_SCL);             // Set SCL High,Clock bit out
if (CHKBIT(IIC_PIN, IIC_SDA)) buff = buff | 0x01; // Read data on SDA pin
CLRBIT(IIC_PORT, IIC_SCL);             // Clear SCL
}
return buff; // Return our I2C byte
}

void IIC_WriteOneByteAddressDevice(uint8 u8_HardwareAddress, uint8 u8_MemoryAddress, uint8 u8_Data)
{
uint16 c;                   // Temp Ram used for write delay

IIC_Start();          // Set I2C start condition
IIC_WriteControl(u8_HardwareAddress, 0);                   // Send the EEPROM control Byte
IIC_WriteByte(u8_MemoryAddress);       // Send the EEPROM internal Address
IIC_WriteByte(u8_Data);       // Send the EEPROM Data
IIC_Stop();             // Set I2C Stop condition
for(c = 0; c < 1000; c++);                           // Delay for EEPROM Write
}

uint8 IIC_ReadOneByteAddressDevice(uint8 u8_HardwareAddress, uint8 u8_MemoryAddress)
{
uint8 Temp;    // Temp RAM for EEPROM Read

IIC_Start();    // Set I2C start condition
IIC_WriteControl(u8_HardwareAddress, 0);                      // Send the EEPROM control Byte
IIC_WriteByte(u8_MemoryAddress); // Send the EEPROM internal Address
IIC_Start();    // Set I2C start condition
IIC_WriteControl(u8_HardwareAddress, 1);                      // Send the EEPROM control Byte
Temp = IIC_ReadByte();             // Read data from EEPROM
IIC_Stop();       // Set I2C Stop condition
return Temp; // Return data from EEPROM
}

void IIC_WriteTwoOneByteAddressDevice(uint8 u8_HardwareAddress, uint16 u16_MemoryAddress, uint8 u8_Data)
{
uint16 c;
                  // Temp Ram used for write delay
uint8 u8_HighAddress;
uint8 u8_LowAddress;
u8_HighAddress = u16_MemoryAddress / 256;
u8_LowAddress = u16_MemoryAddress % 256;
IIC_Start();          // Set I2C start condition
IIC_WriteControl(u8_HardwareAddress, 0);                      // Send the EEPROM control Byte
IIC_WriteByte(u8_HighAddress);
IIC_WriteByte(u8_LowAddress);       // Send the EEPROM internal Address
IIC_WriteByte(u8_Data);       // Send the EEPROM Data
IIC_Stop();             // Set I2C Stop condition
for(c = 0; c < 1000; c++);                           // Delay for EEPROM Write

}

uint8 IIC_ReadTwoOneByteAddressDevice(uint8 u8_HardwareAddress, uint16 u16_MemoryAddress)
{
uint8 Temp;    // Temp RAM for EEPROM Read
uint8 u8_HighAddress;
uint8 u8_LowAddress;

u8_HighAddress = u16_MemoryAddress / 256;
u8_LowAddress = u16_MemoryAddress % 256;
IIC_Start();    // Set I2C start condition
IIC_WriteControl(u8_HardwareAddress, 0); // Send the EEPROM control Byte
IIC_WriteByte(u8_HighAddress);
IIC_WriteByte(u8_LowAddress); // Send the EEPROM internal Address
IIC_Start();    // Set I2C start condition
IIC_WriteControl(u8_HighAddress, 1); // Send the EEPROM control Byte
Temp = IIC_ReadByte();             // Read data from EEPROM
IIC_Stop();       // Set I2C Stop condition
return Temp; // Return data from EEPROM
}

#endif

1万 · 2013-6-20 22:47

#ifndef IIC_H_
#define IIC_H_

//函数原型声明
void IIC_Init(void);
void IIC_Delay(void);
void IIC_Start(void);
void IIC_Stop(void);
void IIC_Clock(void);
uint8 IIC_Ackn(void);
void IIC_WriteControl(uint8 u8_HardwareAddress, uint8 u8_ReadOrWrite);
void IIC_WriteByte(uint8 u8_Data);
uint8 IIC_ReadByte(void);
void IIC_WriteOneByteAddressDevice(uint8 u8_HardwareAddress, uint8 u8_MemoryAddress, uint8 u8_Data);
uint8 IIC_ReadOneByteAddressDevice(uint8 u8_HardwareAddress, uint8 u8_MemoryAddress);
void IIC_WriteTwoOneByteAddressDevice(uint8 u8_HardwareAddress, uint16 u16_MemoryAddress, uint8 u8_Data);
uint8 IIC_ReadTwoOneByteAddressDevice(uint8 u8_HardwareAddress, uint16 u16_MemoryAddress);

#endif /* IIC_H_ */

1万 · 2013-6-20 22:48

#ifndef IIC_CONFIG_H_
#define IIC_CONFIG_H_

#define IIC_PORT PORTD
#define IIC_DDR    DDRD
#define IIC_PIN    PIND

#define IIC_SCL    BIT2
#define IIC_SDA  BIT3

#endif /* IIC_CONFIG_H_ */

1万 · 2013-6-20 22:50

这是用avr写的iic的读写函数用的IO模拟的模式没用过pic 你先对一下代码吧估计差不多

1万 · 2013-6-21 19:05

时间，其实关键还是延时时间...

只看该作者 · 2013-6-21 22:20

你看看你DS18B20接的脚位对不对？呵呵，2脚是DQ

只看该作者 · 2013-6-22 17:16

forgivexx 发表于 2013-6-21 21:28
楼上的，不是I2C，DS18B20是单总线的。调试起来主要还是看时序图。多说无益，你花了半个月太夸张了。仔细看 ...

恩我也觉得太夸张了，所以来求救了，延时这些我都看过，一直不知道哪里出了问题。读写我也是按照时序来写还是不对

只看该作者 · 2013-6-22 17:22

seacore_2008 发表于 2013-6-21 22:20
你看看你DS18B20接的脚位对不对？呵呵，2脚是DQ

恩这个必须不能出错的检查过的

只看该作者 · 2013-6-22 17:23

ningling_21 发表于 2013-6-21 19:05
时间，其实关键还是延时时间...

EN ,我在好好看看，真的还是需要点耐心的

只看该作者 · 2013-6-23 11:27

其实还是自己出现了问题，仿照了以前dsp用过的程序，以为释放总线就是输出高电平就行了，其实不是，pic18f258的释放总线只要把io口切换成输入就行了。希望后面的同学看到有所参考

1万 · 2013-6-23 22:11

paulful 发表于 2013-6-23 11:27
其实还是自己出现了问题，仿照了以前dsp用过的程序，以为释放总线就是输出高电平就行了，其实不是，pic18f ...

明白了就好

只看该作者 · 2013-6-24 16:15

qin552011373 发表于 2013-6-23 22:11
明白了就好

谢谢版主了。

只看该作者 · 2013-7-3 22:20

进步了

跪求指导！ds18b20读不到温度，用示波器打过，读那一段有问

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