| 18,7 → 18,18 |
|---|
| //#define sht_data_pin PIN_D0 |
| //#define sht_clk_pin PIN_D1 |
| |
| #include <math.h> |
| |
| |
| #define noACK 0 |
| #define ACK 1 |
| //adr command r/w |
| #define STATUS_REG_W 0x06 //000 0011 0 |
| #define STATUS_REG_R 0x07 //000 0011 1 |
| #define MEASURE_TEMP 0x03 //000 0001 1 |
| #define MEASURE_HUMI 0x05 //000 0010 1 |
| #define RESET 0x1e //000 1111 0 |
| |
| //***** Function to alert SHT75 ***** |
| // generates a transmission start |
| // _____ ________ |
| 152,6 → 163,7 |
|---|
| // DATA: |_______| |
| // _ _ _ _ _ _ _ _ _ ___ ___ |
| // SCK : __| |__| |__| |__| |__| |__| |__| |__| |__| |______| |___| |______ |
| |
| void sht_comreset (void) |
| { |
| int8 i; |
| 179,6 → 191,17 |
|---|
| delay_ms(15); //pause 15 ms |
| } |
| |
| //---------------------------------------------------------------------------------- |
| char sht_write_statusreg(unsigned char *p_value) |
| //---------------------------------------------------------------------------------- |
| // writes the status register with checksum (8-bit) |
| { |
| unsigned char error=0; |
| sht_comstart(); //transmission start |
| error+=sht_comwrite(STATUS_REG_W);//send command to sensor |
| error+=sht_comwrite(*p_value); //send value of status register |
| return error; //error>=1 in case of no response form the sensor |
| } |
| |
| //***** Function to measure SHT75 temperature ***** |
| |
| 216,6 → 239,11 |
|---|
| |
| void calculate_data (int16 temp, int16 humid, float & tc, float & rhlin, float & rhtrue) |
| { |
| const float C1=-2.0468; // for 12 Bit RH |
| const float C2=+0.0367; // for 12 Bit RH |
| const float C3=-0.0000015955; // for 12 Bit RH |
| const float T1=+0.01; // for 12 Bit RH |
| const float T2=+0.00008; // for 12 Bit RH |
| float rh; |
| |
| //calculate temperature reading |
| 224,10 → 252,13 |
|---|
| //calculate Real RH reading |
| rh = (float) humid; |
| |
| rhlin = (rh * 0.0405) - (rh * rh * 0.0000028) - 4.0; |
| rhlin = C1 + (rh * C2) + (rh * rh * C3); |
| |
| //calculate True RH reading |
| rhtrue = ((tc - 25.0) * (0.01 + (0.00008 * rh))) + rhlin; |
| |
| if(rhtrue>99)rhtrue=100; //cut if the value is outside of |
| if(rhtrue<0.1)rhtrue=0.1; //the physical possible range |
| } |
| |
| |
| 252,3 → 283,17 |
|---|
| sht_comreset(); //reset SHT75 |
| delay_ms(20); //delay for power-up |
| } |
| |
| //-------------------------------------------------------------------- |
| float calc_dewpoint(float h,float t) |
| //-------------------------------------------------------------------- |
| // calculates dew point |
| // input: humidity [%RH], temperature [K] |
| // output: dew point [K] |
| { float k,dew_point ; |
| |
| k = (log10(h)-2)/0.4343 + (17.62*t)/(243.12+t); |
| dew_point = 243.12*k/(17.62-k); |
| return dew_point; |
| } |
| |