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| /////////////////////////////////////////////////////////////////////////////// |
| // // |
| // Driver file for SHT75 Temperature & Humidity Sensor // |
| // // |
| // ***** To initialise SHT75 sensor upon power up ***** // |
| // // |
| // Function : sht_init() // |
| // Return : none // |
| // // |
| // // |
| // ***** To measure and caluculate SHT75 temp & real RH ***** // |
| // // |
| // Function : sht_rd (temp, truehumid) // |
| // Return : temperature & true humidity in float values // |
| // // |
| /////////////////////////////////////////////////////////////////////////////// |
| |
| #define sht_data_pin PIN_D0 |
| #define sht_clk_pin PIN_D1 |
| |
| |
| //***** Function to alert SHT75 ***** |
| |
| void comstart (void) |
| { |
| output_float(sht_data_pin); //data high |
| output_low(sht_clk_pin); //clk low |
| delay_us(2); |
| output_high(sht_clk_pin); //clk high |
| delay_us(2); |
| output_low(sht_data_pin); //data low |
| delay_us(2); |
| output_low(sht_clk_pin); //clk low |
| delay_us(5); |
| output_high(sht_clk_pin); //clk high |
| delay_us(2); |
| output_float(sht_data_pin); //data high |
| delay_us(2); |
| output_low(sht_clk_pin); //clk low |
| } |
| |
| |
| //***** Function to write data to SHT75 ***** |
| |
| int1 comwrite (int8 iobyte) |
| { |
| int8 i, mask = 0x80; |
| int1 ack; |
| |
| //Shift out command |
| delay_us(5); |
| for(i=0; i<8; i++) |
| { |
| output_low(sht_clk_pin); //clk low |
| if((iobyte & mask) > 0) output_float(sht_data_pin); //data high if MSB high |
| else output_low(sht_data_pin); //data low if MSB low |
| delay_us(2); |
| output_high(sht_clk_pin); //clk high |
| delay_us(2); |
| mask = mask >> 1; //shift to next bit |
| } |
| |
| //Shift in ack |
| output_low(sht_clk_pin); //clk low |
| delay_us(2); |
| ack = input(sht_data_pin); //get ack bit |
| output_high(sht_clk_pin); //clk high |
| delay_us(2); |
| output_low(sht_clk_pin); //clk low |
| return(ack); |
| } |
| |
| |
| //***** Function to read data from SHT75 ***** |
| |
| int16 comread (void) |
| { |
| int8 i; |
| int16 iobyte = 0; |
| const int16 mask0 = 0x0000; |
| const int16 mask1 = 0x0001; |
| |
| //shift in MSB data |
| for(i=0; i<8; i++) |
| { |
| iobyte = iobyte << 1; |
| output_high(sht_clk_pin); //clk high |
| delay_us(2); |
| if (input(sht_data_pin)) iobyte |= mask1; //shift in data bit |
| else iobyte |= mask0; |
| output_low(sht_clk_pin); //clk low |
| delay_us(2); |
| } |
| |
| //send ack 0 bit |
| output_low(sht_data_pin); //data low |
| delay_us(2); |
| output_high(sht_clk_pin); //clk high |
| delay_us(5); |
| output_low(sht_clk_pin); //clk low |
| delay_us(2); |
| output_float(sht_data_pin); //data high |
| |
| //shift in LSB data |
| for(i=0; i<8; i++) |
| { |
| iobyte = iobyte << 1; |
| output_high(sht_clk_pin); //clk high |
| delay_us(2); |
| if (input(sht_data_pin)) iobyte |= mask1; //shift in data bit |
| else iobyte |= mask0; |
| output_low(sht_clk_pin); //clk low |
| delay_us(2); |
| } |
| |
| //send ack 1 bit |
| output_float(sht_data_pin); //data high |
| delay_us(2); |
| output_high(sht_clk_pin); //clk high |
| delay_us(5); |
| output_low(sht_clk_pin); //clk low |
| |
| return(iobyte); |
| } |
| |
| |
| //***** Function to wait for SHT75 reading ***** |
| |
| void comwait (void) |
| { |
| int16 sht_delay; |
| |
| output_float(sht_data_pin); //data high |
| output_low(sht_clk_pin); //clk low |
| delay_us(2); |
| for(sht_delay=0; sht_delay<30000; sht_delay++) // wait for max 300ms |
| { |
| if (!input(sht_data_pin)) break; //if sht_data_pin low, SHT75 ready |
| delay_us(10); |
| } |
| } |
| |
| |
| //***** Function to reset SHT75 communication ***** |
| |
| void comreset (void) |
| { |
| int8 i; |
| |
| output_float(sht_data_pin); //data high |
| output_low(sht_clk_pin); //clk low |
| delay_us(5); |
| for(i=0; i<9; i++) |
| { |
| output_high(sht_clk_pin); //toggle clk 9 times |
| delay_us(5); |
| output_low(sht_clk_pin); |
| delay_us(5); |
| } |
| comstart(); |
| } |
| |
| |
| //***** Function to soft reset SHT75 ***** |
| |
| void sht_soft_reset (void) |
| { |
| comreset(); //SHT75 communication reset |
| comwrite(0x1e); //send SHT75 reset command |
| delay_ms(15); //pause 15 ms |
| } |
| |
| |
| //***** Function to measure SHT75 temperature ***** |
| |
| int16 measuretemp (void) |
| { |
| int1 ack; |
| int16 iobyte; |
| |
| comstart(); //alert SHT75 |
| ack = comwrite(0x03); //send measure temp command and read ack status |
| if(ack == 1) return; |
| comwait(); //wait for SHT75 measurement to complete |
| iobyte = comread(); //read SHT75 temp data |
| return(iobyte); |
| } |
| |
| |
| //***** Function to measure SHT75 RH ***** |
| |
| int16 measurehumid (void) |
| { |
| int1 ack; |
| int16 iobyte; |
| |
| comstart(); //alert SHT75 |
| ack = comwrite(0x05); //send measure RH command and read ack status |
| if(ack == 1) return; |
| comwait(); //wait for SHT75 measurement to complete |
| iobyte = comread(); //read SHT75 temp data |
| return(iobyte); |
| } |
| |
| |
| //***** Function to calculate SHT75 temp & RH ***** |
| |
| void calculate_data (int16 temp, int16 humid, float & tc, float & rhlin, float & rhtrue) |
| { |
| float truehumid1, rh; |
| |
| //calculate temperature reading |
| tc = ((float) temp * 0.01) - 40.0; |
| |
| //calculate Real RH reading |
| rh = (float) humid; |
| |
| rhlin = (rh * 0.0405) - (rh * rh * 0.0000028) - 4.0; |
| |
| //calculate True RH reading |
| rhtrue = ((tc - 25.0) * (0.01 + (0.00008 * rh))) + rhlin; |
| } |
| |
| |
| //***** Function to measure & calculate SHT75 temp & RH ***** |
| |
| void sht_rd (float & temp, float & truehumid) |
| { |
| int16 restemp, reshumid; |
| float realhumid; |
| restemp = 0; truehumid = 0; |
| |
| restemp = measuretemp(); //measure temp |
| reshumid = measurehumid(); //measure RH |
| calculate_data (restemp, reshumid, temp, realhumid, truehumid); //calculate temp & RH |
| } |
| |
| |
| //***** Function to initialise SHT75 on power-up ***** |
| |
| void sht_init (void) |
| { |
| comreset(); //reset SHT75 |
| delay_ms(20); //delay for power-up |
| } |
| /////////////////////////////////////////////////////////////////////////////// |
| // // |
| // Driver file for SHT75 Temperature & Humidity Sensor // |
| // // |
| // ***** To initialise SHT75 sensor upon power up ***** // |
| // // |
| // Function : sht_init() // |
| // Return : none // |
| // // |
| // // |
| // ***** To measure and caluculate SHT75 temp & real RH ***** // |
| // // |
| // Function : sht_rd (temp, truehumid) // |
| // Return : temperature & true humidity in float values // |
| // // |
| /////////////////////////////////////////////////////////////////////////////// |
| |
| //#define sht_data_pin PIN_D0 |
| //#define sht_clk_pin PIN_D1 |
| |
| |
| //***** Function to alert SHT75 ***** |
| |
| void comstart (void) |
| { |
| output_float(sht_data_pin); //data high |
| output_low(sht_clk_pin); //clk low |
| delay_us(2); |
| output_high(sht_clk_pin); //clk high |
| delay_us(2); |
| output_low(sht_data_pin); //data low |
| delay_us(2); |
| output_low(sht_clk_pin); //clk low |
| delay_us(5); |
| output_high(sht_clk_pin); //clk high |
| delay_us(2); |
| output_float(sht_data_pin); //data high |
| delay_us(2); |
| output_low(sht_clk_pin); //clk low |
| } |
| |
| |
| //***** Function to write data to SHT75 ***** |
| |
| int1 comwrite (int8 iobyte) |
| { |
| int8 i, mask = 0x80; |
| int1 ack; |
| |
| //Shift out command |
| delay_us(5); |
| for(i=0; i<8; i++) |
| { |
| output_low(sht_clk_pin); //clk low |
| if((iobyte & mask) > 0) output_float(sht_data_pin); //data high if MSB high |
| else output_low(sht_data_pin); //data low if MSB low |
| delay_us(2); |
| output_high(sht_clk_pin); //clk high |
| delay_us(2); |
| mask = mask >> 1; //shift to next bit |
| } |
| |
| //Shift in ack |
| output_low(sht_clk_pin); //clk low |
| delay_us(2); |
| ack = input(sht_data_pin); //get ack bit |
| output_high(sht_clk_pin); //clk high |
| delay_us(2); |
| output_low(sht_clk_pin); //clk low |
| return(ack); |
| } |
| |
| |
| //***** Function to read data from SHT75 ***** |
| |
| int16 comread (void) |
| { |
| int8 i; |
| int16 iobyte = 0; |
| const int16 mask0 = 0x0000; |
| const int16 mask1 = 0x0001; |
| |
| //shift in MSB data |
| for(i=0; i<8; i++) |
| { |
| iobyte = iobyte << 1; |
| output_high(sht_clk_pin); //clk high |
| delay_us(2); |
| if (input(sht_data_pin)) iobyte |= mask1; //shift in data bit |
| else iobyte |= mask0; |
| output_low(sht_clk_pin); //clk low |
| delay_us(2); |
| } |
| |
| //send ack 0 bit |
| output_low(sht_data_pin); //data low |
| delay_us(2); |
| output_high(sht_clk_pin); //clk high |
| delay_us(5); |
| output_low(sht_clk_pin); //clk low |
| delay_us(2); |
| output_float(sht_data_pin); //data high |
| |
| //shift in LSB data |
| for(i=0; i<8; i++) |
| { |
| iobyte = iobyte << 1; |
| output_high(sht_clk_pin); //clk high |
| delay_us(2); |
| if (input(sht_data_pin)) iobyte |= mask1; //shift in data bit |
| else iobyte |= mask0; |
| output_low(sht_clk_pin); //clk low |
| delay_us(2); |
| } |
| |
| //send ack 1 bit |
| output_float(sht_data_pin); //data high |
| delay_us(2); |
| output_high(sht_clk_pin); //clk high |
| delay_us(5); |
| output_low(sht_clk_pin); //clk low |
| |
| return(iobyte); |
| } |
| |
| |
| //***** Function to wait for SHT75 reading ***** |
| |
| void comwait (void) |
| { |
| int16 sht_delay; |
| |
| output_float(sht_data_pin); //data high |
| output_low(sht_clk_pin); //clk low |
| delay_us(2); |
| for(sht_delay=0; sht_delay<30000; sht_delay++) // wait for max 300ms |
| { |
| if (!input(sht_data_pin)) break; //if sht_data_pin low, SHT75 ready |
| delay_us(10); |
| } |
| } |
| |
| |
| //***** Function to reset SHT75 communication ***** |
| |
| void comreset (void) |
| { |
| int8 i; |
| |
| output_float(sht_data_pin); //data high |
| output_low(sht_clk_pin); //clk low |
| delay_us(5); |
| for(i=0; i<9; i++) |
| { |
| output_high(sht_clk_pin); //toggle clk 9 times |
| delay_us(5); |
| output_low(sht_clk_pin); |
| delay_us(5); |
| } |
| comstart(); |
| } |
| |
| |
| //***** Function to soft reset SHT75 ***** |
| |
| void sht_soft_reset (void) |
| { |
| comreset(); //SHT75 communication reset |
| comwrite(0x1e); //send SHT75 reset command |
| delay_ms(15); //pause 15 ms |
| } |
| |
| |
| //***** Function to measure SHT75 temperature ***** |
| |
| int16 measuretemp (void) |
| { |
| int1 ack; |
| int16 iobyte; |
| |
| comstart(); //alert SHT75 |
| ack = comwrite(0x03); //send measure temp command and read ack status |
| if(ack == 1) return; |
| comwait(); //wait for SHT75 measurement to complete |
| iobyte = comread(); //read SHT75 temp data |
| return(iobyte); |
| } |
| |
| |
| //***** Function to measure SHT75 RH ***** |
| |
| int16 measurehumid (void) |
| { |
| int1 ack; |
| int16 iobyte; |
| |
| comstart(); //alert SHT75 |
| ack = comwrite(0x05); //send measure RH command and read ack status |
| if(ack == 1) return; |
| comwait(); //wait for SHT75 measurement to complete |
| iobyte = comread(); //read SHT75 temp data |
| return(iobyte); |
| } |
| |
| |
| //***** Function to calculate SHT75 temp & RH ***** |
| |
| void calculate_data (int16 temp, int16 humid, float & tc, float & rhlin, float & rhtrue) |
| { |
| float truehumid1, rh; |
| |
| //calculate temperature reading |
| tc = ((float) temp * 0.01) - 40.0; |
| |
| //calculate Real RH reading |
| rh = (float) humid; |
| |
| rhlin = (rh * 0.0405) - (rh * rh * 0.0000028) - 4.0; |
| |
| //calculate True RH reading |
| rhtrue = ((tc - 25.0) * (0.01 + (0.00008 * rh))) + rhlin; |
| } |
| |
| |
| //***** Function to measure & calculate SHT75 temp & RH ***** |
| |
| void sht_rd (float & temp, float & truehumid) |
| { |
| int16 restemp, reshumid; |
| float realhumid; |
| restemp = 0; truehumid = 0; |
| |
| restemp = measuretemp(); //measure temp |
| reshumid = measurehumid(); //measure RH |
| calculate_data (restemp, reshumid, temp, realhumid, truehumid); //calculate temp & RH |
| } |
| |
| |
| //***** Function to initialise SHT75 on power-up ***** |
| |
| void sht_init (void) |
| { |
| comreset(); //reset SHT75 |
| delay_ms(20); //delay for power-up |
| } |