//===========================================================================
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_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;
}
bool ICACHE_FLASH_ATTR sht21_getHumidity(float *humidity){
uint8_t data[3], i;
uint16_t tmp;
bool status = false;
if(!commandOnlyWrite(SHT21_ADDR, 0xF5)){
return false;
}
for(i = 0, status = false; (i < 85) && !status; i++){
os_delay_us(1000);
status = byteReadNoReg(SHT21_ADDR, data, 3);
}
if(status){
if(SHT2x_CheckCrc(data, 2, data[2])){
tmp = (uint16_t)data[0] << 8 | (data[1] & 0xFC);
*humidity = -6.0 + 125.0 * ((float) tmp / 65536);
return true;
}
}
return false;
}
bool ICACHE_FLASH_ATTR sht21_getTemperature(float *temperature){
uint8_t data[3], i;
uint16_t tmp;
bool status = false;
if(!commandOnlyWrite(SHT21_ADDR, 0xF3)){
return false;
}
for(i = 0, status = false; (i < 85) && !status; i++){
os_delay_us(1000);
status = byteReadNoReg(SHT21_ADDR, data, 3);
}
if(status){
if(SHT2x_CheckCrc(data, 2, data[2])){
tmp = (uint16_t)data[0] << 8 | (data[1] & 0xFC);
*temperature = -46.85 + 175.72 * ((float) tmp / 65536);
return true;
}
}
return false;
}
