htu21d: sensor added

Signed-off-by: William Penner <william.penner@intel.com>
Signed-off-by: Brendan Le Foll <brendan.le.foll@intel.com>

src/htu21d/CMakeLists.txt

@@ -0,0 +1,5 @@
+set (libname "htu21d")
+set (libdescription "libupm Humidity Sensor")
+set (module_src ${libname}.cpp)
+set (module_h ${libname}.h)
+upm_module_init()

src/htu21d/htu21d.cpp

@@ -0,0 +1,243 @@
+/*
+ * Author: William Penner <william.penner@intel.com>
+ * Copyright (c) 2014 Intel Corporation.
+ *
+ * This driver supports the HTU21D digital humidity and temperature
+ * sensor. The datasheet is available from:
+ * http://www.meas-spec.com/downloads/HTU21D.pdf
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+#include <iostream>
+#include <unistd.h>
+#include <stdlib.h>
+
+#include "htu21d.h"
+
+using namespace upm;
+
+HTU21D::HTU21D(int bus, int devAddr) {
+    m_temperature = 0;
+    m_humidity    = 0;
+
+    m_name = HTU21D_NAME;
+
+    m_controlAddr = devAddr;
+    m_bus = bus;
+
+    m_i2ControlCtx = mraa_i2c_init(m_bus);
+
+    mraa_result_t ret = mraa_i2c_address(m_i2ControlCtx, m_controlAddr);
+    if (ret != MRAA_SUCCESS) {
+        fprintf(stderr, "Error accessing i2c bus\n");
+    }
+}
+
+HTU21D::~HTU21D() {
+    mraa_i2c_stop(m_i2ControlCtx);
+}
+
+int32_t
+HTU21D::htu21_temp_ticks_to_millicelsius(int ticks)
+{
+    ticks &= ~0x0003; /* clear status bits */
+    /*
+     * Formula T = -46.85 + 175.72 * ST / 2^16 from datasheet p14,
+     * optimized for integer fixed point (3 digits) arithmetic
+     */
+    return ((21965 * (int32_t)ticks) >> 13) - 46850;
+}
+
+int32_t
+HTU21D::htu21_rh_ticks_to_per_cent_mille(int ticks)
+{
+    ticks &= ~0x0003; /* clear status bits */
+    /*
+     * Formula RH = -6 + 125 * SRH / 2^16 from datasheet p14,
+     * optimized for integer fixed point (3 digits) arithmetic
+     */
+    return ((15625 * (int32_t)ticks) >> 13) - 6000;
+}
+
+int
+HTU21D::sampleData(void)
+{
+    uint32_t itemp;
+
+    itemp = i2cReadReg_16(HTU21D_T_MEASUREMENT_HM);
+    m_temperature = htu21_temp_ticks_to_millicelsius(itemp);
+
+    itemp = i2cReadReg_16(HTU21D_RH_MEASUREMENT_HM);
+    m_humidity = htu21_rh_ticks_to_per_cent_mille(itemp);
+
+    return 0;
+}
+
+int32_t
+HTU21D::getTemperature(void)
+{
+    return m_temperature;
+}
+
+int32_t
+HTU21D::getHumidity(void)
+{
+    return m_humidity;
+}
+
+/*
+ * This is the primary function to read the data.  It will initiate
+ * a measurement cycle and will then return both the humidity and
+ * temperature values.  piTemperature can be NULL.
+ */
+
+int32_t
+HTU21D::getRHumidity(int32_t* piTemperature)
+{
+    sampleData();
+    if (NULL != piTemperature)
+        *piTemperature = m_temperature;
+    return m_humidity;
+}
+
+/*
+ * Use the compensation equation from the datasheet to correct the
+ * current reading
+ * RHcomp = RHactualT + (25 - Tactual) * CoeffTemp
+ * RHcomp is in units of %RH * 1000
+ */
+int32_t
+HTU21D::getCompRH(void)
+{
+    return m_humidity + (25000 - m_temperature) * 3 / 20;
+}
+
+
+/*
+ * Test function: when reading the HTU21D many times rapidly should
+ * result in a temperature increase.  This test will verify that the
+ * value is changing from read to read
+ */
+
+int
+HTU21D::testSensor(void)
+{
+    int iError = 0;
+    int i, j;
+    int32_t iTemp, iHum;
+    int32_t iTempMax, iTempMin;
+    int32_t iHumMax, iHumMin;
+    int32_t iHumFirst, iTempFirst;
+
+    fprintf(stdout, "Executing Sensor Test.\n  Reading registers 100 times to look for operation\n" );
+
+    iHum = getRHumidity(&iTemp);
+    iTempFirst = iTempMax = iTempMin = iTemp;
+    iHumFirst  = iHumMax  = iHumMin  = iHum;
+
+    for (i=0; i < 100; i++) {
+        iHum = getRHumidity(&iTemp);
+        if (iHum  < iHumMin)  iHumMin  = iHum;
+        if (iHum  > iHumMax)  iHumMax  = iHum;
+        if (iTemp < iTempMin) iTempMin = iTemp;
+        if (iTemp > iTempMax) iTempMax = iTemp;
+//        fprintf(stdout, "Temp: %d  Humidity: %d\n", iTemp, iHum);
+    }
+
+    if ((iTemp - iTempFirst) <= 0) {
+        fprintf(stdout, "! Temperature should have increased, but didn't\n" );
+        iError++;
+    }
+
+    if (iHumMin == iHumMax) {
+        fprintf(stdout, "! Humidity was unchanged - not working?\n" );
+        iError++;
+    }
+
+    if (iTempMin == iTempMax) {
+        fprintf(stdout, "! Temperature was unchanged - not working?\n" );
+        iError++;
+    }
+
+    if (iError == 0) {
+        fprintf(stdout, "  Device appears functional\n" );
+    }
+
+    fprintf(stdout, "  Test complete\n" );
+
+    return iError;
+}
+
+/*
+ * Functions to read and write data to the i2c device
+ */
+
+mraa_result_t
+HTU21D::i2cReadRegValue(int reg, uint32_t* puint32, int ibytes) {
+    uint32_t data = 0;
+
+    if (ibytes > 4)
+        ibytes = 4;
+
+    mraa_i2c_address(m_i2ControlCtx, m_controlAddr);
+    mraa_i2c_write_byte(m_i2ControlCtx, reg);
+
+    mraa_i2c_address(m_i2ControlCtx, m_controlAddr);
+    mraa_i2c_read(m_i2ControlCtx, (uint8_t *)&data, ibytes);
+
+    fprintf(stdout, "reg data = %08x\n", data);
+    *puint32 = be32toh(data) >> ((4-ibytes) * 8);
+    fprintf(stdout, "reg return = %08x\n", *puint32);
+
+    return MRAA_SUCCESS;
+}
+
+mraa_result_t
+HTU21D::i2cWriteReg (uint8_t reg, uint8_t value) {
+    mraa_result_t error = MRAA_SUCCESS;
+
+    uint8_t data[2] = { reg, value };
+    error = mraa_i2c_address (m_i2ControlCtx, m_controlAddr);
+    error = mraa_i2c_write (m_i2ControlCtx, data, 2);
+
+    return error;
+}
+
+/*
+ * Function to read 16 bits starting at reg.  This function
+ * was replaced due to functionality of using read() to
+ * access i2c data.
+ */
+uint16_t
+HTU21D::i2cReadReg_16 (int reg) {
+    uint16_t data;
+    mraa_i2c_address(m_i2ControlCtx, m_controlAddr);
+    data  = (uint16_t)mraa_i2c_read_byte_data(m_i2ControlCtx, reg) << 8;
+    data |= (uint16_t)mraa_i2c_read_byte_data(m_i2ControlCtx, reg+1);
+    return data;
+}
+
+/*
+ * Function to read 8 bits starting at reg.  This function
+ * was replaced due to functionality of using read() to
+ * access i2c data.
+ */
+uint8_t
+HTU21D::i2cReadReg_8 (int reg) {
+    mraa_i2c_address(m_i2ControlCtx, m_controlAddr);
+    return mraa_i2c_read_byte_data(m_i2ControlCtx, reg);
+}
+

src/htu21d/htu21d.h

@@ -0,0 +1,169 @@
+/*
+ * Author: William Penner <william.penner@intel.com>
+ * Copyright (c) 2014 Intel Corporation.
+ *
+ * Based on code adapted from the kernel HTU21 driver and
+ * code by: Yevgeniy Kiveisha <yevgeniy.kiveisha@intel.com>
+ * Copyright (c) 2014 Intel Corporation.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
+ */
+
+#pragma once
+
+#include <string>
+#include <mraa/i2c.h>
+#include <math.h>
+
+#define HTU21D_NAME     "htu21d"
+#define HTU21D_I2C_ADDRESS  0x40
+
+/* HTU21 Commands */
+#define HTU21D_T_MEASUREMENT_HM   0xE3
+#define HTU21D_RH_MEASUREMENT_HM  0xE5
+
+namespace upm {
+
+/**
+ * @brief HTU21D humidity sensor library
+ * @defgroup htu21d libupm-htu21
+ */
+
+/**
+ * @brief C++ API for HTU21D chip (Atmospheric Pressure Sensor)
+ *
+ * Measurement Specialties [HTU21D]
+ * (http://www.meas-spec.com/downloads/HTU21D.pdf)
+ * is a digital humidity sensor with temperature output.
+ * RH will report between 0 and 100% and temperature range is
+ * -40 to +125 degC
+ *
+ * @ingroup htu21d i2c
+ * @snippet htu21d.cxx Interesting
+ * @image html htu21d.jpeg
+ */
+class HTU21D {
+    public:
+        /**
+         * Instanciates a HTU21D object
+         *
+         * @param bus number of used bus
+         * @param devAddr address of used i2c device
+         * @param mode HTU21D oversampling
+         */
+        HTU21D (int bus=0, int devAddr=HTU21D_I2C_ADDRESS);
+
+        /**
+         * HTU21D object destructor, basicaly it close i2c connection.
+         */
+        ~HTU21D ();
+
+        /**
+         * Initiate a temp/pressure mesasurement and wait for function
+         * to complete.  The humidity and temp registers can be read
+         * after this call.
+         */
+        int sampleData(void);
+        
+        /**
+         * Get the current measured humidity [RH * 1000]
+         * To convert to Relative Humidity, divide by 1000
+         *
+         */
+        int32_t getHumidity(void);
+
+        /**
+         * Get the humidity cell temperature [degC * 1000]
+         * To convert to Temperature, divide by 1000
+         */
+        int32_t getTemperature(void);
+        
+        /**
+         * Reads both temperature and humidity together
+         * To convert to Relative Humidity, divide by 1000
+         * To convert to Temperature, divide by 1000
+         *
+         * @param pointer to int32_t buffer for temp
+         */
+        int32_t getRHumidity(int32_t* iTemperature);
+        
+        /**
+         * Using the current humidity and temperature the function
+         * will calculate the compensated RH using the equation from
+         * the datasheet.
+         */
+        int32_t getCompRH(void);
+        
+        /**
+         * Function intended to test the device and verify it
+         * is correctly operating.
+         *
+         */
+        int testSensor(void);
+        
+        /**
+         * Read 1 to 4 bytes from i2c registers
+         *
+         * @param reg address of a register
+         * @param puint32 pointer to buffer for register data
+         * @param ibytes number of bytes to be returned
+         */
+        mraa_result_t i2cReadRegValue (int reg, uint32_t* puint32, int ibytes);
+
+        /**
+         * Read two bytes register
+         *
+         * @param reg address of a register
+         */
+        uint16_t i2cReadReg_16 (int reg);
+
+        /**
+         * Write to one byte register
+         *
+         * @param reg address of a register
+         * @param value byte to be written
+         */
+        mraa_result_t i2cWriteReg (uint8_t reg, uint8_t value);
+
+        /**
+         * Read one byte register
+         *
+         * @param reg address of a register
+         */
+        uint8_t i2cReadReg_8 (int reg);
+
+    private:
+
+        /**
+         * Convert temp register to value * 1000
+         */
+        int32_t htu21_temp_ticks_to_millicelsius(int ticks);
+
+        /**
+         * Convert temp register to value * 1000
+         */
+        int32_t htu21_rh_ticks_to_per_cent_mille(int ticks);
+
+        std::string m_name;
+
+        int m_controlAddr;
+        int m_bus;
+        mraa_i2c_context m_i2ControlCtx;
+        
+        int32_t m_temperature;
+        int32_t m_humidity;
+};
+
+}

src/htu21d/jsupm_htu21d.i

@@ -0,0 +1,8 @@
+%module jsupm_htu21d
+%include "../upm.i"
+
+%{
+    #include "htu21d.h"
+%}
+
+%include "htu21d.h"

src/htu21d/pyupm_htu21d.i

@@ -0,0 +1,13 @@
+%module pyupm_htu21d
+%include "../upm.i"
+
+%feature("autodoc", "3");
+
+#ifdef DOXYGEN
+%include "htu21d_doc.i"
+#endif
+
+%include "htu21d.h"
+%{
+    #include "htu21d.h"
+%}