Diff: hts221_driver.cpp

Revision:

0:9d5134074d84

Child:

1:af7a42f7d465

--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/hts221_driver.cpp	Fri Jul 08 23:52:38 2016 +0000
@@ -0,0 +1,247 @@
+
+#include "HTS221.h"
+
+
+// ------------------------------------------------------------------------------
+//jmf  -- define I2C pins and functions to read & write to I2C device
+
+#include <string>
+#include "mbed.h"
+
+I2C i2c(PTC11, PTC10);    //SDA, SCL -- define the I2C pins being used
+
+// Read a single unsigned char from addressToRead and return it as a unsigned char
+unsigned char HTS221::readRegister(unsigned char slaveAddress, unsigned char ToRead)
+{
+    char data = ToRead;
+
+    i2c.write(slaveAddress, &data, 1, 0);
+    i2c.read(slaveAddress, &data, 1, 0);
+    return data;
+}
+
+// Writes a single unsigned char (dataToWrite) into regToWrite
+int HTS221::writeRegister(unsigned char slaveAddress, unsigned char regToWrite, unsigned char dataToWrite)
+{
+    const char data[] = {regToWrite, dataToWrite};
+
+    return i2c.write(slaveAddress,data,2,0);
+}
+
+
+//jmf end
+// ------------------------------------------------------------------------------
+
+static inline int humidityReady(uint8_t data) {
+    return (data & 0x02);
+}
+static inline int temperatureReady(uint8_t data) {
+    return (data & 0x01);
+}
+
+
+HTS221::HTS221(void) : _address(HTS221_ADDRESS)
+{
+    _temperature = 0;
+    _humidity = 0;
+}
+
+
+int HTS221::begin(void)
+{
+    uint8_t data;
+
+    data = readRegister(_address, WHO_AM_I);
+    if (data == WHO_AM_I_RETURN){
+        if (activate()){
+            storeCalibration();
+            return data;
+        }
+    }
+
+    return 0;
+}
+
+int
+HTS221::storeCalibration(void)
+{
+    uint8_t data;
+    uint16_t tmp;
+
+    for (int reg=CALIB_START; reg<=CALIB_END; reg++) {
+        if ((reg!=CALIB_START+8) && (reg!=CALIB_START+9) && (reg!=CALIB_START+4)) {
+
+            data = readRegister(HTS221_ADDRESS, reg);
+
+            switch (reg) {
+            case CALIB_START:
+                _h0_rH = data;
+                break;
+            case CALIB_START+1:
+            _h1_rH = data;
+            break;
+            case CALIB_START+2:
+            _T0_degC = data;
+            break;
+            case CALIB_START+3:
+            _T1_degC = data;
+            break;
+
+            case CALIB_START+5:
+            tmp = _T0_degC;
+            _T0_degC = (data&0x3)<<8;
+            _T0_degC |= tmp;
+
+            tmp = _T1_degC;
+            _T1_degC = ((data&0xC)>>2)<<8;
+            _T1_degC |= tmp;
+            break;
+            case CALIB_START+6:
+            _H0_T0 = data;
+            break;
+            case CALIB_START+7:
+            _H0_T0 |= data<<8;
+            break;
+            case CALIB_START+0xA:
+            _H1_T0 = data;
+            break;
+            case CALIB_START+0xB:
+            _H1_T0 |= data <<8;
+            break;
+            case CALIB_START+0xC:
+            _T0_OUT = data;
+            break;
+            case CALIB_START+0xD:
+            _T0_OUT |= data << 8;
+            break;
+            case CALIB_START+0xE:
+            _T1_OUT = data;
+            break;
+            case CALIB_START+0xF:
+            _T1_OUT |= data << 8;
+            break;
+
+
+            case CALIB_START+8:
+            case CALIB_START+9:
+            case CALIB_START+4:
+            //DO NOTHING
+            break;
+
+            // to cover any possible error
+            default:
+                return false;
+            } /* switch */
+        } /* if */
+    }  /* for */
+    return true;
+}
+
+
+int
+HTS221::activate(void)
+{
+    uint8_t data;
+
+    data = readRegister(_address, CTRL_REG1);
+    data |= POWER_UP;
+    data |= ODR0_SET;
+    writeRegister(_address, CTRL_REG1, data);
+
+    return true;
+}
+
+
+int HTS221::deactivate(void)
+{
+    uint8_t data;
+
+    data = readRegister(_address, CTRL_REG1);
+    data &= ~POWER_UP;
+    writeRegister(_address, CTRL_REG1, data);
+    return true;
+}
+
+
+int
+HTS221::bduActivate(void)
+{
+    uint8_t data;
+
+    data = readRegister(_address, CTRL_REG1);
+    data |= BDU_SET;
+    writeRegister(_address, CTRL_REG1, data);
+
+    return true;
+}
+
+
+int
+HTS221::bduDeactivate(void)
+{
+    uint8_t data;
+
+    data = readRegister(_address, CTRL_REG1);
+    data &= ~BDU_SET;
+    writeRegister(_address, CTRL_REG1, data);
+    return true;
+}
+
+
+int
+HTS221::readHumidity(void)
+{
+    uint8_t data   = 0;
+    uint16_t h_out = 0;
+    double h_temp  = 0.0;
+    double hum     = 0.0;
+
+    data = readRegister(_address, STATUS_REG);
+
+    if (data & HUMIDITY_READY) {
+        data = readRegister(_address, HUMIDITY_H_REG);
+        h_out = data << 8;  // MSB
+        data = readRegister(_address, HUMIDITY_L_REG);
+        h_out |= data;      // LSB
+
+        // Decode Humidity
+        hum = ((int16_t)(_h1_rH) - (int16_t)(_h0_rH))/2.0;  // remove x2 multiple
+
+        // Calculate humidity in decimal of grade centigrades i.e. 15.0 = 150.
+        h_temp = (((int16_t)h_out - (int16_t)_H0_T0) * hum) / ((int16_t)_H1_T0 - (int16_t)_H0_T0);
+        hum    = ((int16_t)_h0_rH) / 2.0; // remove x2 multiple
+        _humidity = (int16_t)((hum + h_temp)); // provide signed % measurement unit
+    }
+    return _humidity;
+}
+
+
+
+double
+HTS221::readTemperature(void)
+{
+    uint8_t data   = 0;
+    uint16_t t_out = 0;
+    double t_temp  = 0.0;
+    double deg     = 0.0;
+
+    data = readRegister(_address, STATUS_REG);
+
+    if (data & TEMPERATURE_READY) {
+
+        data= readRegister(_address, TEMP_H_REG);
+        t_out = data  << 8; // MSB
+        data = readRegister(_address, TEMP_L_REG);
+        t_out |= data;      // LSB
+
+        // Decode Temperature
+        deg    = ((int16_t)(_T1_degC) - (int16_t)(_T0_degC))/8.0; // remove x8 multiple
+
+        // Calculate Temperature in decimal of grade centigrades i.e. 15.0 = 150.
+        t_temp = (((int16_t)t_out - (int16_t)_T0_OUT) * deg) / ((int16_t)_T1_OUT - (int16_t)_T0_OUT);
+        deg    = ((int16_t)_T0_degC) / 8.0;     // remove x8 multiple
+        _temperature = deg + t_temp;   // provide signed celsius measurement unit
+    }
+
+    return _temperature;
+}