SHT21 驅動代碼

//============================================================================== // S E N S I R I O N AG, Laubisruetistr. 50, CH-8712 Staefa, Switzerland //============================================================================== // Project : SHT2x Sample Code (V1.2) // File : SHT2x.c // Author : MST // Controller: NEC V850/SG3 (uPD70F3740) // Compiler : IAR compiler for V850 (3.50A) // Brief : Sensor layer. Functions for sensor access //============================================================================== //---------- Includes ---------------------------------------------------------- #include "SHT2x.h" //============================================================================== u8t SHT2x_CheckCrc(u8t data[], u8t nbrOfBytes, u8t checksum) //============================================================================== { u8t crc = 0; u8t byteCtr; //calculates 8-Bit checksum with given polynomial for (byteCtr = 0; byteCtr < nbrOfBytes; ++byteCtr) { crc ^= (data[byteCtr]); for (u8t bit = 8; bit > 0; --bit) { if (crc & 0x80) crc = (crc << 1) ^ POLYNOMIAL; else crc = (crc << 1); } } if (crc != checksum) return CHECKSUM_ERROR; else return 0; } //=========================================================================== u8t SHT2x_ReadUserRegister(u8t *pRegisterValue) //=========================================================================== { u8t checksum; //variable for checksum byte u8t error=0; //variable for error code I2c_StartCondition(); error |= I2c_WriteByte (I2C_ADR_W); error |= I2c_WriteByte (USER_REG_R); I2c_StartCondition(); error |= I2c_WriteByte (I2C_ADR_R); *pRegisterValue = I2c_ReadByte(ACK); checksum=I2c_ReadByte(NO_ACK); error |= SHT2x_CheckCrc (pRegisterValue,1,checksum); I2c_StopCondition(); return error; } //=========================================================================== u8t SHT2x_WriteUserRegister(u8t *pRegisterValue) //=========================================================================== { u8t error=0; //variable for error code I2c_StartCondition(); error |= I2c_WriteByte (I2C_ADR_W); error |= I2c_WriteByte (USER_REG_W); error |= I2c_WriteByte (*pRegisterValue); I2c_StopCondition(); return error; } //=========================================================================== u8t SHT2x_MeasureHM(etSHT2xMeasureType eSHT2xMeasureType, nt16 *pMeasurand) //=========================================================================== { u8t checksum; //checksum u8t data[2]; //data array for checksum verification u8t error=0; //error variable u16t i; //counting variable //-- write I2C sensor address and command -- I2c_StartCondition(); error |= I2c_WriteByte (I2C_ADR_W); // I2C Adr switch(eSHT2xMeasureType) { case HUMIDITY: error |= I2c_WriteByte (TRIG_RH_MEASUREMENT_HM); break; case TEMP : error |= I2c_WriteByte (TRIG_T_MEASUREMENT_HM); break; default: assert(0); } //-- wait until hold master is released -- I2c_StartCondition(); error |= I2c_WriteByte (I2C_ADR_R); SCL=HIGH; // set SCL I/O port as input for(i=0; i<1000; i++) // wait until master hold is released or { DelayMicroSeconds(1000); // a timeout (~1s) is reached if (SCL_CONF==1) break; } //-- check for timeout -- if(SCL_CONF==0) error |= TIME_OUT_ERROR; //-- read two data bytes and one checksum byte -- pMeasurand->s16.u8H = data[0] = I2c_ReadByte(ACK); pMeasurand->s16.u8L = data[1] = I2c_ReadByte(ACK); checksum=I2c_ReadByte(NO_ACK); //-- verify checksum -- error |= SHT2x_CheckCrc (data,2,checksum); I2c_StopCondition(); return error; } //=========================================================================== u8t SHT2x_MeasurePoll(etSHT2xMeasureType eSHT2xMeasureType, nt16 *pMeasurand) //=========================================================================== { u8t checksum; //checksum u8t data[2]; //data array for checksum verification u8t error=0; //error variable u16t i=0; //counting variable //-- write I2C sensor address and command -- I2c_StartCondition(); error |= I2c_WriteByte (I2C_ADR_W); // I2C Adr switch(eSHT2xMeasureType) { case HUMIDITY: error |= I2c_WriteByte (TRIG_RH_MEASUREMENT_POLL); break; case TEMP : error |= I2c_WriteByte (TRIG_T_MEASUREMENT_POLL); break; default: assert(0); } //-- poll every 10ms for measurement ready. Timeout after 20 retries (200ms)-- do { I2c_StartCondition(); DelayMicroSeconds(10000); //delay 10ms if(i++ >= 20) break; } while(I2c_WriteByte (I2C_ADR_R) == ACK_ERROR); if (i>=20) error |= TIME_OUT_ERROR; //-- read two data bytes and one checksum byte -- pMeasurand->s16.u8H = data[0] = I2c_ReadByte(ACK); pMeasurand->s16.u8L = data[1] = I2c_ReadByte(ACK); checksum=I2c_ReadByte(NO_ACK); //-- verify checksum -- error |= SHT2x_CheckCrc (data,2,checksum); I2c_StopCondition(); return error; } //=========================================================================== u8t SHT2x_SoftReset() //=========================================================================== { u8t error=0; //error variable I2c_StartCondition(); error |= I2c_WriteByte (I2C_ADR_W); // I2C Adr error |= I2c_WriteByte (SOFT_RESET); // Command I2c_StopCondition(); DelayMicroSeconds(15000); // wait till sensor has restarted return error; } //============================================================================== float SHT2x_CalcRH(u16t u16sRH) //============================================================================== { ft humidityRH; // variable for result u16sRH &= ~0x0003; // clear bits [1..0] (status bits) //-- calculate relative humidity [%RH] -- humidityRH = -6.0 + 125.0/65536 * (ft)u16sRH; // RH= -6 + 125 * SRH/2^16 return humidityRH; } //============================================================================== float SHT2x_CalcTemperatureC(u16t u16sT) //============================================================================== { ft temperatureC; // variable for result u16sT &= ~0x0003; // clear bits [1..0] (status bits) //-- calculate temperature [�C] -- temperatureC= -46.85 + 175.72/65536 *(ft)u16sT; //T= -46.85 + 175.72 * ST/2^16 return temperatureC; } //============================================================================== u8t SHT2x_GetSerialNumber(u8t u8SerialNumber[]) //============================================================================== { u8t error=0; //error variable //Read from memory location 1 I2c_StartCondition(); error |= I2c_WriteByte (I2C_ADR_W); //I2C address error |= I2c_WriteByte (0xFA); //Command for readout on-chip memory error |= I2c_WriteByte (0x0F); //on-chip memory address I2c_StartCondition(); error |= I2c_WriteByte (I2C_ADR_R); //I2C address u8SerialNumber[5] = I2c_ReadByte(ACK); //Read SNB_3 I2c_ReadByte(ACK); //Read CRC SNB_3 (CRC is not analyzed) u8SerialNumber[4] = I2c_ReadByte(ACK); //Read SNB_2 I2c_ReadByte(ACK); //Read CRC SNB_2 (CRC is not analyzed) u8SerialNumber[3] = I2c_ReadByte(ACK); //Read SNB_1 I2c_ReadByte(ACK); //Read CRC SNB_1 (CRC is not analyzed) u8SerialNumber[2] = I2c_ReadByte(ACK); //Read SNB_0 I2c_ReadByte(NO_ACK); //Read CRC SNB_0 (CRC is not analyzed) I2c_StopCondition(); //Read from memory location 2 I2c_StartCondition(); error |= I2c_WriteByte (I2C_ADR_W); //I2C address error |= I2c_WriteByte (0xFC); //Command for re