#include "SHT3X.H"

/*================================================================
【名 称】
【功 能】模拟IIC使用的引脚定义，注意要上拉电阻
【备 注】
【作 者】
【时 间】
================================================================*/
//sbit SDA=P3^3;  //大板子引脚定义
//sbit SCL=P5^4;

sbit SDA=P5^4; //小板子引脚定义
sbit SCL=P3^3;

#define POLYNOMIAL  0x31 // P(x) = x^8 + x^5 + x^4 + 1 = 00110001

//==============================================================================
unsigned char SHT3X_CalcCrc(unsigned char *crcdata, unsigned char nbrOfBytes){
//==============================================================================
    unsigned char Bit;        // bit mask
  unsigned char crc = 0xFF; // calculated checksum
  unsigned char byteCtr;    // byte counter
  
  // calculates 8-Bit checksum with given polynomial
  for(byteCtr = 0; byteCtr < nbrOfBytes; byteCtr++)
  {
    crc ^= (crcdata[byteCtr]);
    for(Bit = 8; Bit > 0; --Bit)
    {
      if(crc & 0x80) crc = (crc << 1) ^ POLYNOMIAL;
      else           crc = (crc << 1);
    }
  }
    return crc;
}
///*================================================================
//【名 称】void Delay(unsigned int t)
//【功 能】延时长
//【备 注】
//【作 者】
//【时 间】
//================================================================*/
//void Delay(unsigned int t)
//{
//    unsigned char i;
//    while(t--)
//    {
//        for(i=0;i<200;i++);
//    }                       
//}
//void Delay1ms()        //@24.000MHz
//{
//    unsigned char i, j;

//    i = 24;
//    j = 85;
//    do
//    {
//        while (--j);
//    } while (--i);
//}

//***********************以下是模拟I2C函数****************************//
/*================================================================
【名 称】void I2CDelay (unsigned char t)
【功 能】模拟IIC用的短延时
【备 注】
【作 者】
【时 间】
================================================================*/
void I2CDelay (unsigned char t)
{
    while(t--);
}
/*================================================================
【名 称】void I2CInit(void)
【功 能】I2C初始化，空闲状态
【备 注】
【作 者】
【时 间】
================================================================*/
void I2CInit(void)
{
    SDA = 1;
    SCL = 1;
}
/*================================================================
【名 称】void I2CStart(void)
【功 能】I2C起始信号
【备 注】SCL、SDA同为高，SDA跳变成低之后，SCL跳变成低
【作 者】
【时 间】
================================================================*/
void I2CStart(void)
{
      SDA = 1;
      SCL = 1;
      I2CDelay(10);
      SDA = 0;
      I2CDelay(20);
      SCL = 0;
      I2CDelay(20);
}
/*================================================================
【名 称】void I2CStop(void)
【功 能】I2C停止信号
【备 注】SCL、SDA同为低，SCL跳变成高之后，SDA跳变成高
【作 者】
【时 间】
================================================================*/
void I2CStop(void)
{
      SDA = 0;
      SCL = 0;
      I2CDelay(10);
      SCL = 1;
      I2CDelay(10);
      SDA = 1;
      I2CDelay(10);
}
/*================================================================
【名 称】unsigned char I2CWRByte(unsigned char WRByte)
【功 能】I2C写一个字节数据，返回ACK或者NACK
【备 注】从高到低，依次发送
【作 者】
【时 间】
================================================================*/
etError I2CWRByte(unsigned char WRByte)
{
    unsigned char i;
    SCL = 0;
    for(i=0;i<8;i++)
    {
        if(WRByte&0x80)
        {
            SDA = 1;   
        }
        else
        {
            SDA = 0;
        }
        I2CDelay(10);
        SCL=1;            //输出SDA稳定后，拉高SCL给出上升沿，从机检测到后进行数据采样
        I2CDelay(50);
        SCL=0;
        I2CDelay(10);
        WRByte <<= 1;
    }
    SDA = 1;
    SCL = 1;
    I2CDelay(20);
    if(SDA==1)            //SDA为高，收到NACK
    {
        SCL=0;
        I2CDelay(50);
        return ACK_ERROR;   
    }
    else                 //SDA为低，收到ACK
    {
        SCL=0;
        I2CDelay(50);
        return NO_ERROR;
    }
}
/*================================================================
【名 称】unsigned char I2CRDByte(unsigned char AckValue)
【功 能】I2C读一个字节数据，入口参数用于控制应答状态，ACK或者NACK
【备 注】从高到低，依次接收
【作 者】
【时 间】
================================================================*/
unsigned char I2CRDByte(unsigned char AckValue)
{
    unsigned char i,RDByte=0;
    SCL = 0;
    SDA = 1;            //释放总线   
    for (i=0;i<8;i++)
    {
        RDByte <<= 1;    //移位
        SCL = 1;        //给出上升沿
        I2CDelay(30);    //延时等待信号稳定
        if(SDA==1)         //采样获取数据
        {
            RDByte |= 0x01;
        }
        else
        {
            RDByte &= 0xfe;
        }
        SCL = 0;           //下降沿，从机给出下一位值
        I2CDelay(10);
    }   
    SDA =  AckValue;    //应答状态
    I2CDelay(10);
    SCL = 1;                        
      I2CDelay(50);         
      SCL = 0;
      SDA = 1;               
      I2CDelay(1);
    return RDByte;
}
etError SHT3X_WriteCommand(etCommands cmd){
//==============================================================================
  etError error; // error code
  // write the upper 8 bits of the command to the sensor
  error  = I2CWRByte(cmd >> 8);
  // write the lower 8 bits of the command to the sensor
  error |= I2CWRByte(cmd & 0xFF);
   
  return error;
}
/*================================================================
【名 称】void SHT3XInit(void)
【功 能】SHT3X初始化函数，主函数中调用
【备 注】
【作 者】
【时 间】
================================================================*/
void SHT3XInit(void)
{

    I2CInit();//I2C初始化
//    I2CStart();
//  I2CWRByte(SHT3XWriteHeader);
//    SHT3X_WriteCommand(CMD_CLEAR_STATUS); //
//    I2CStop();
//   
   
  I2CStart();
  I2CWRByte(SHT3XWriteHeader);
    SHT3X_WriteCommand(CMD_MEAS_PERI_1_H); //1秒高精度循环测量模式
    I2CStop();
   
   
}




//==============================================================================循环读取模式
etError SHT3X_XHGetTempAndHumi(int        *temp,
                               int        *humi){
//==============================================================================
  etError error;           // error code
  unsigned long int    rawValueTemp;    // temperature raw value from sensor
  unsigned long int    rawValueHumi;    // humidity raw value from sensor
    unsigned char Rdata[6]={0};
  unsigned char i;                                                                             
  I2CStart();
  error  = I2CWRByte(SHT3XWriteHeader);
  // if no error ...
  if(error == NO_ERROR)
  {
    // start measurement in polling mode
    // use depending on the required repeatability, the corresponding command
     error = SHT3X_WriteCommand(CMD_FETCH_DATA);
  }
  // if no error, wait until measurement ready
  if(error == NO_ERROR)
  {
         I2CStart();
     error = I2CWRByte(SHT3XReadHeader);
      // if measurement has finished -> exit loop
  }
    // if no error, read temperature and humidity raw values
  if(error == NO_ERROR)
  {
        for(i=0;i<5;i++)
        {
            Rdata[i] = I2CRDByte(ACK);
        }
    Rdata[i] = I2CRDByte(NACK);
        I2CStop();
        if(Rdata[2]!=SHT3X_CalcCrc(Rdata,2))     error = CHECKSUM_ERROR;
      if(Rdata[5]!=SHT3X_CalcCrc(&Rdata[3],2)) error = CHECKSUM_ERROR;   
  }
  // if no error, calculate temperature in  and humidity in %RH
  if(error == NO_ERROR)
  {
        rawValueTemp =(Rdata[0] << 8) | Rdata[1];
        rawValueHumi =(Rdata[3] << 8) | Rdata[4];
    *temp =(int)(1750 *rawValueTemp / 65535 - 450);
    *humi =(int)(1000 *rawValueHumi / 65535);
  }
  return error;
}






////==============================================================================  单次读取模式
//etError SHT3X_GetTempAndHumi(int        *temp,
//                                     int         *humi,
//                                     etRepeatab repeatab,
//                                     unsigned char   timeout){
////==============================================================================
//  etError error;           // error code
//  unsigned long int    rawValueTemp;    // temperature raw value from sensor
//  unsigned long int    rawValueHumi;    // humidity raw value from sensor
//    unsigned char Rdata[6]={0};
//  unsigned char i;                                                                             
//  I2CStart();
//  error  = I2CWRByte(SHT3XWriteHeader);

//  // if no error ...
//  if(error == NO_ERROR)
//  {
//    // start measurement in polling mode
//    // use depending on the required repeatability, the corresponding command
//    switch(repeatab)
//    {
//      case REPEATAB_LOW:    error = SHT3X_WriteCommand(CMD_MEAS_POLLING_L); break;
//      case REPEATAB_MEDIUM: error = SHT3X_WriteCommand(CMD_MEAS_POLLING_M); break;
//      case REPEATAB_HIGH:         error = SHT3X_WriteCommand(CMD_MEAS_POLLING_H); break;
//      default:                  error = PARM_ERROR; break;
//    }
//  }
//   
//   
//  
//  // if no error, wait until measurement ready
//  if(error == NO_ERROR)
//  {
//    // poll every 1ms for measurement ready until timeout
//    while(timeout--)
//    {
//      // check if the measurement has finished
//            I2CStop();
//            
//            I2CStart();
//      error = I2CWRByte(SHT3XReadHeader);

//      // if measurement has finished -> exit loop
//      if(error == NO_ERROR) break;

//      // delay 1ms
//      Delay1ms();
//    }
//         
//        // check for timeout error
//        if(timeout == 0) error = TIMEOUT_ERROR;
//  }
//   
//    // if no error, read temperature and humidity raw values
//  if(error == NO_ERROR)
//  {
//        for(i=0;i<5;i++)
//        {
//            Rdata[i] = I2CRDByte(ACK);
//        }
//    Rdata[i] = I2CRDByte(NACK);
//        I2CStop();
//        if(Rdata[2]!=SHT3X_CalcCrc(Rdata,2))     error = CHECKSUM_ERROR;
//      if(Rdata[5]!=SHT3X_CalcCrc(&Rdata[3],2)) error = CHECKSUM_ERROR;   
//  }
//  // if no error, calculate temperature in  and humidity in %RH
//  if(error == NO_ERROR)
//  {
//        rawValueTemp =(Rdata[0] << 8) | Rdata[1];
//        rawValueHumi =(Rdata[3] << 8) | Rdata[4];
//    *temp =(int)( 1750 *rawValueTemp / 65535 - 450);
//    *humi =(int)(1000 *rawValueHumi / 65535);
//  }
//  return error;
//}

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