//----------------------------------------------------------------------------------
unsigned char sht_measure(sht_value *p_sht_value, unsigned char *p_checksum, unsigned char mode, unsigned char pin)
//----------------------------------------------------------------------------------
// makes a measurement (humidity/temperature) with checksum
{
unsigned char error=0;
unsigned char i;
sht_value this_sht_value;
/* sht_transstart(pin); //transmission start */
sht_connectionreset(pin);
switch(mode)
{ //send command to sensor
case TEMP : error+=sht_write_byte(MEASURE_TEMP, pin); /*usart_write("TEMP: ");*/ break;
case HUMI : error+=sht_write_byte(MEASURE_HUMI, pin); /*usart_write("HUMI: ");*/ break;
default : break;
}
for (i=0;i<500;i++) {
if(SHT_DATA(pin)==0) break; //wait until sensor has finished the measurement
_delay_ms(1); // neccesary since the AVR is so much faster than the old 8051
// and the 210ms for 14bit measuremnt are only a rough estimate
}
if(SHT_DATA(pin)) error+=1; // or timeout is reached
this_sht_value.i = 256*sht_read_byte(ACK, pin); //read the first byte (MSB)
this_sht_value.i +=sht_read_byte(ACK, pin); //read the second byte (LSB)
*p_checksum =sht_read_byte(noACK, pin); //read checksum
*(p_sht_value)= this_sht_value;
return error;
}
//----------------------------------------------------------------------------------
// resets the sensor by a softreset
//----------------------------------------------------------------------------------
char sht_softreset(void)
{
unsigned char error=0;
sht_connectionreset(); //reset communication
error+=sht_write_byte(RESET); //send RESET-command to sensor
return error; //error=1 in case of no response form the sensor
}
//----------------------------------------------------------------------------------
char sht_do_measure(unsigned char Sensor){
//----------------------------------------------------------------------------------
// sample program that shows how to use SHT11 functions
// 1. connection reset
// 2. measure humidity [ticks](12 bit) and temperature [ticks](14 bit)
// 3. calculate humidity [%RH] and temperature [°C]
// 4. calculate dew point [°C]
// 5. print temperature, humidity, dew point
unsigned int humi_val_i;
unsigned int temp_val_i;
Values humi_val;
Values temp_val;
unsigned char error,checksum;
unsigned int i;
float humi_val_f;
float temp_val_f;
error=sht_SetSensor(Sensor);
sht_connectionreset();
SHTdevice_table[CurrentSensorIndex].valid = 0;
error+=sht_measure(HUMI); //measure humidity
humi_val_i = CurrentValue;
error+=sht_measure(TEMP); //measure temperature
temp_val_i = CurrentValue;
if(error!=0) {
sht_connectionreset();
} //in case of an error: connection reset
else
{ humi_val_f = (float)humi_val_i; //converts integer to float
temp_val_f = (float)temp_val_i; //converts integer to float
calc_sth11(&humi_val_f,&temp_val_f);
SHTdevice_table[CurrentSensorIndex].humidity = (unsigned char)humi_val_f;
SHTdevice_table[CurrentSensorIndex].temperature = (int)(temp_val_f*100);
SHTdevice_table[CurrentSensorIndex].valid = 1;
}
return error;
}
//----------------------------------------------------------------------------------
unsigned char sht_softreset(unsigned char pin)
//----------------------------------------------------------------------------------
// resets the sensor by a softreset
{
// rockclimber
MAKE_SHT_SCK_PIN_OUTPUT;
asm volatile ("nop"::);
unsigned char error=0;
sht_connectionreset(pin); //reset communication
error+=sht_write_byte(RESET_SHT, pin); //send RESET_SHT-command to sensor
return error; //error=1 in case of no response form the sensor
}
