Diff: lib_SHT25.cpp

Revision:

0:71da3fbfe141

Child:

1:ebd95757fba4

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/lib_SHT25.cpp	Mon Jun 18 08:05:58 2018 +0000
@@ -0,0 +1,125 @@
+/** SHT25 class
+*
+* @purpose       library for SHT25 humidity and temperature sensor
+*
+* Use to get temperature and humidity
+*
+* https://www.sensirion.com/products/humidity-sensor/
+*
+* Example:
+* @code
+* #include "mbed.h"
+* #include "lib_SHT25.h"
+*  
+* Serial pc(USBTX, USBRX);
+* SHT25  sensor(p28, p27);
+* 
+* int main()
+* {
+*     float temperature, humidity;
+*     while(1)
+*     {
+*         sensor.getData(&temperature, &humidity);
+*         pc.printf("\rtemperature = %6.2f%cC -|- humidity = %6.2f%%RH", temperature, 248, humidity);
+*         wait(0.5);
+*     }
+* }
+* @endcode
+* @file          lib_SHT25.h 
+* @date          Jun 2018
+* @author        Yannic Simon
+*/
+#include "lib_SHT25.h"
+
+SHT25::SHT25(PinName sda, PinName scl) : _i2c(sda, scl)
+{
+    softReset();
+    wait_ms(100);
+    setPrecision(SHT_PREC_1214);
+    _selfHeat = true;
+}
+
+float SHT25::getTemperature(void)
+{
+    if(_selfHeat)
+    {
+        _selfHeat = false;
+        _t.attach(callback(this, &SHT25::keepSelf), SHT_SELF_HEATING);
+        return readTemperature();
+    }
+    return _temperature;
+}
+
+float SHT25::readTemperature(void)
+{
+    char command[1] = {SHT_TRIG_TEMP}, rx[3] = {0xFF, 0xFF, 0xFF};
+    
+    _i2c.write(SHT_I2C_ADDR, command, 1, false);
+    wait_ms(85);
+    _i2c.read(SHT_I2C_ADDR, rx, 3, false);
+    
+    return _temperature = -46.85 + 175.72 * ((((rx[0] << 8) | rx[1]) & 0xFFFC) / 65536.0);
+}
+
+float SHT25::getHumidity(void)
+{
+    if(_selfHeat)
+    {
+        _selfHeat = false;
+        _t.attach(callback(this, &SHT25::keepSelf), SHT_SELF_HEATING);
+        return readHumidity();
+    }
+    return _humidity;
+}
+
+float SHT25::readHumidity(void)
+{
+    char command[1] = {SHT_TRIG_RH}, rx[3] = {0xFF, 0xFF, 0xFF};
+    
+    _i2c.write(SHT_I2C_ADDR, command, 1, false);
+    wait_ms(29);
+    _i2c.read(SHT_I2C_ADDR, rx, 3, false);
+    
+    return _humidity = -6.0 + 125.0 * ((((rx[0] << 8) | rx[1]) & 0xFFFC) / 65536.0);
+}
+
+void SHT25::getData(float *tempC, float *relHumidity)
+{
+    if(_selfHeat)
+    {
+        _selfHeat = false;
+        _t.attach(callback(this, &SHT25::keepSelf), SHT_SELF_HEATING);
+        readData(tempC, relHumidity);
+    }
+}
+
+void SHT25::readData(float *tempC, float *relHumidity)
+{
+    *tempC = readTemperature();
+    *relHumidity = readHumidity();
+}
+
+int SHT25::setPrecision(char precision)
+{
+    char command[2] = {SHT_WRITE_REG, precision};
+
+    return _i2c.write(SHT_I2C_ADDR, command, 2, false);
+}
+
+bool SHT25::softReset()
+{
+    char command[1] = {SHT_SOFT_RESET};
+    
+    if (_i2c.write(SHT_I2C_ADDR, command, 1, false) != 0)
+    {
+        wait_ms(15);
+        return false;
+    }
+    
+    return true;
+}
+
+void SHT25::keepSelf(void)
+{
+    _selfHeat = true;
+}
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