Y SI / lib_SHT25

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Dependents:   lib_SHT25_example

lib_SHT25.cpp@4:21a50575cb79, 2019-12-03 (annotated)

Committer:
YSI
Date:
Tue Dec 03 09:23:44 2019 +0000
Revision:
4:21a50575cb79
Parent:
3:81324c19d870
Child:
5:8e34f365eb45
change depreciated wait_ms to wait_us.

Who changed what in which revision?

UserRevisionLine numberNew contents of line
YSI 0:71da3fbfe141 1 /** SHT25 class
YSI 0:71da3fbfe141 2 *
YSI 0:71da3fbfe141 3 * @purpose library for SHT25 humidity and temperature sensor
YSI 0:71da3fbfe141 4 *
YSI 0:71da3fbfe141 5 * Use to get temperature and humidity
YSI 0:71da3fbfe141 6 *
YSI 0:71da3fbfe141 7 * https://www.sensirion.com/products/humidity-sensor/
YSI 0:71da3fbfe141 8 *
YSI 0:71da3fbfe141 9 * Example:
YSI 0:71da3fbfe141 10 * @code
YSI 0:71da3fbfe141 11 * #include "mbed.h"
YSI 0:71da3fbfe141 12 * #include "lib_SHT25.h"
YSI 0:71da3fbfe141 13 *
YSI 0:71da3fbfe141 14 * Serial pc(USBTX, USBRX);
YSI 3:81324c19d870 15 * SHT25 sensor(I2C_SDA, I2C_SCL);
YSI 0:71da3fbfe141 16 *
YSI 0:71da3fbfe141 17 * int main()
YSI 0:71da3fbfe141 18 * {
YSI 0:71da3fbfe141 19 * float temperature, humidity;
YSI 0:71da3fbfe141 20 * while(1)
YSI 0:71da3fbfe141 21 * {
YSI 3:81324c19d870 22 * temperature = sensor.getTemperature();
YSI 3:81324c19d870 23 * humidity = sensor.getTemperature();
YSI 3:81324c19d870 24 * pc.printf("\r\ntemperature = %6.2f%cC -|- humidity = %6.2f%%RH", temperature, 248, humidity);
YSI 3:81324c19d870 25 * sensor.waitSafeHeat();
YSI 0:71da3fbfe141 26 * sensor.getData(&temperature, &humidity);
YSI 3:81324c19d870 27 * pc.printf("\ntemperature = %6.2f%cC -|- humidity = %6.2f%%RH", temperature, 248, humidity);
YSI 3:81324c19d870 28 * sensor.waitSafeHeat();
YSI 0:71da3fbfe141 29 * }
YSI 0:71da3fbfe141 30 * }
YSI 0:71da3fbfe141 31 * @endcode
YSI 1:ebd95757fba4 32 * @file lib_SHT25.cpp
YSI 0:71da3fbfe141 33 * @date Jun 2018
YSI 0:71da3fbfe141 34 * @author Yannic Simon
YSI 0:71da3fbfe141 35 */
YSI 0:71da3fbfe141 36 #include "lib_SHT25.h"
YSI 0:71da3fbfe141 37
YSI 0:71da3fbfe141 38 SHT25::SHT25(PinName sda, PinName scl) : _i2c(sda, scl)
YSI 0:71da3fbfe141 39 {
YSI 4:21a50575cb79 40 wait_us(SHT_WAIT_US_SET);
YSI 0:71da3fbfe141 41 softReset();
YSI 0:71da3fbfe141 42 setPrecision(SHT_PREC_1214);
YSI 3:81324c19d870 43 _temperature = _humidity = NAN;
YSI 3:81324c19d870 44 _selfHeatTemperature = _selfHeatHumidity = true;
YSI 0:71da3fbfe141 45 }
YSI 0:71da3fbfe141 46
YSI 0:71da3fbfe141 47 float SHT25::getTemperature(void)
YSI 0:71da3fbfe141 48 {
YSI 3:81324c19d870 49 if(_selfHeatTemperature)
YSI 0:71da3fbfe141 50 {
YSI 3:81324c19d870 51 _selfHeatTemperature = false;
YSI 3:81324c19d870 52 _t.attach(callback(this, &SHT25::keepSafeTemperature), SHT_SELF_HEATING);
YSI 2:34e14b4cd981 53 return _temperature = readTemperature();
YSI 0:71da3fbfe141 54 }
YSI 0:71da3fbfe141 55 return _temperature;
YSI 0:71da3fbfe141 56 }
YSI 0:71da3fbfe141 57
YSI 0:71da3fbfe141 58 float SHT25::readTemperature(void)
YSI 0:71da3fbfe141 59 {
YSI 0:71da3fbfe141 60 char command[1] = {SHT_TRIG_TEMP}, rx[3] = {0xFF, 0xFF, 0xFF};
YSI 0:71da3fbfe141 61
YSI 2:34e14b4cd981 62 if(!_i2c.write(SHT_I2C_ADDR, command, 1, false))
YSI 2:34e14b4cd981 63 {
YSI 4:21a50575cb79 64 wait_us(SHT_WAIT_US_TEMP);
YSI 2:34e14b4cd981 65 if(!_i2c.read(SHT_I2C_ADDR, rx, 3, false))
YSI 2:34e14b4cd981 66 return -46.85 + 175.72 * ((((rx[0] << 8) | rx[1]) & 0xFFFC) / 65536.0);
YSI 2:34e14b4cd981 67 }
YSI 2:34e14b4cd981 68 return NAN;
YSI 0:71da3fbfe141 69 }
YSI 0:71da3fbfe141 70
YSI 0:71da3fbfe141 71 float SHT25::getHumidity(void)
YSI 0:71da3fbfe141 72 {
YSI 3:81324c19d870 73 if(_selfHeatHumidity)
YSI 0:71da3fbfe141 74 {
YSI 3:81324c19d870 75 _selfHeatHumidity = false;
YSI 3:81324c19d870 76 _h.attach(callback(this, &SHT25::keepSafeHumidity), SHT_SELF_HEATING);
YSI 2:34e14b4cd981 77 return _humidity = readHumidity();
YSI 0:71da3fbfe141 78 }
YSI 0:71da3fbfe141 79 return _humidity;
YSI 0:71da3fbfe141 80 }
YSI 0:71da3fbfe141 81
YSI 0:71da3fbfe141 82 float SHT25::readHumidity(void)
YSI 0:71da3fbfe141 83 {
YSI 0:71da3fbfe141 84 char command[1] = {SHT_TRIG_RH}, rx[3] = {0xFF, 0xFF, 0xFF};
YSI 0:71da3fbfe141 85
YSI 2:34e14b4cd981 86 if(!_i2c.write(SHT_I2C_ADDR, command, 1, false))
YSI 2:34e14b4cd981 87 {
YSI 4:21a50575cb79 88 wait_us(SHT_WAIT_US_RH);
YSI 2:34e14b4cd981 89 if(!_i2c.read(SHT_I2C_ADDR, rx, 3, false))
YSI 2:34e14b4cd981 90 return -6.0 + 125.0 * ((((rx[0] << 8) | rx[1]) & 0xFFFC) / 65536.0);
YSI 2:34e14b4cd981 91 }
YSI 2:34e14b4cd981 92 return NAN;
YSI 0:71da3fbfe141 93 }
YSI 0:71da3fbfe141 94
YSI 0:71da3fbfe141 95 void SHT25::getData(float *tempC, float *relHumidity)
YSI 0:71da3fbfe141 96 {
YSI 3:81324c19d870 97 if(_selfHeatTemperature && _selfHeatHumidity)
YSI 0:71da3fbfe141 98 {
YSI 3:81324c19d870 99 _selfHeatTemperature = _selfHeatHumidity = false;
YSI 3:81324c19d870 100 _t.attach(callback(this, &SHT25::keepSafeTemperature), SHT_SELF_HEATING);
YSI 3:81324c19d870 101 _h.attach(callback(this, &SHT25::keepSafeHumidity), SHT_SELF_HEATING);
YSI 0:71da3fbfe141 102 readData(tempC, relHumidity);
YSI 0:71da3fbfe141 103 }
YSI 2:34e14b4cd981 104 else
YSI 2:34e14b4cd981 105 {
YSI 2:34e14b4cd981 106 *tempC = _temperature;
YSI 2:34e14b4cd981 107 *relHumidity = _humidity;
YSI 2:34e14b4cd981 108 }
YSI 0:71da3fbfe141 109 }
YSI 0:71da3fbfe141 110
YSI 0:71da3fbfe141 111 void SHT25::readData(float *tempC, float *relHumidity)
YSI 0:71da3fbfe141 112 {
YSI 2:34e14b4cd981 113 *tempC = _temperature = readTemperature();
YSI 2:34e14b4cd981 114 *relHumidity = _humidity = readHumidity();
YSI 0:71da3fbfe141 115 }
YSI 0:71da3fbfe141 116
YSI 2:34e14b4cd981 117 bool SHT25::setPrecision(char precision)
YSI 0:71da3fbfe141 118 {
YSI 0:71da3fbfe141 119 char command[2] = {SHT_WRITE_REG, precision};
YSI 0:71da3fbfe141 120
YSI 2:34e14b4cd981 121 if(!_i2c.write(SHT_I2C_ADDR, command, 2, false))
YSI 2:34e14b4cd981 122 {
YSI 4:21a50575cb79 123 wait_us(SHT_WAIT_US_SET);
YSI 2:34e14b4cd981 124 return true;
YSI 2:34e14b4cd981 125 }
YSI 2:34e14b4cd981 126 return false;
YSI 0:71da3fbfe141 127 }
YSI 0:71da3fbfe141 128
YSI 0:71da3fbfe141 129 bool SHT25::softReset()
YSI 0:71da3fbfe141 130 {
YSI 0:71da3fbfe141 131 char command[1] = {SHT_SOFT_RESET};
YSI 0:71da3fbfe141 132
YSI 2:34e14b4cd981 133 if (!_i2c.write(SHT_I2C_ADDR, command, 1, false))
YSI 0:71da3fbfe141 134 {
YSI 4:21a50575cb79 135 wait_us(SHT_WAIT_US_SET);
YSI 2:34e14b4cd981 136 return true;
YSI 0:71da3fbfe141 137 }
YSI 2:34e14b4cd981 138 return false;
YSI 0:71da3fbfe141 139 }
YSI 0:71da3fbfe141 140
YSI 3:81324c19d870 141 void SHT25::waitSafeHeat(void)
YSI 3:81324c19d870 142 {
YSI 3:81324c19d870 143 while(!_selfHeatTemperature || !_selfHeatHumidity)
YSI 4:21a50575cb79 144 wait_us(SHT_WAIT_US_SET);
YSI 3:81324c19d870 145 }
YSI 3:81324c19d870 146
YSI 3:81324c19d870 147 void SHT25::keepSafeTemperature(void)
YSI 0:71da3fbfe141 148 {
YSI 3:81324c19d870 149 _selfHeatTemperature = true;
YSI 3:81324c19d870 150 }
YSI 3:81324c19d870 151
YSI 3:81324c19d870 152 void SHT25::keepSafeHumidity(void)
YSI 3:81324c19d870 153 {
YSI 3:81324c19d870 154 _selfHeatHumidity = true;
YSI 0:71da3fbfe141 155 }