sht1x: Initial implementation

This driver was developed with a DFRobot SHT10 Temperature and Humidity
sensor.  This driver should work on all SHT1X devices.

It requires a 10K pull-up resistor connected to the data pin.
The sensor can be run at differing voltages from 2.5v to 5v.

Signed-off-by: Jon Trulson <jtrulson@ics.com>

src/sht1x/sht1x.hpp

@@ -0,0 +1,183 @@
+/*
+ * Author: Jon Trulson <jtrulson@ics.com>
+ * Copyright (c) 2016 Intel Corporation.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining
+ * a copy of this software and associated documentation files (the
+ * "Software"), to deal in the Software without restriction, including
+ * without limitation the rights to use, copy, modify, merge, publish,
+ * distribute, sublicense, and/or sell copies of the Software, and to
+ * permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be
+ * included in all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
+ * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
+ * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
+ * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
+ * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
+ * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+#pragma once
+
+#include <string>
+#include <iostream>
+
+#include <stdlib.h>
+#include <unistd.h>
+
+#include "sht1x.h"
+
+namespace upm {
+  /**
+   * @brief SHT1X Temperature and Humidity Sensor
+   * @defgroup sht1x libupm-sht1x
+   * @ingroup gpio temp
+   */
+
+  /**
+   * @library sht1x
+   * @sensor sht1x
+   * @comname SHT1X Temperature and Humidity Sensor
+   * @type temp
+   * @man dfrobot
+   * @con gpio
+   *
+   * @brief SHT1X Temperature and Humidity Sensor
+   *
+   * This driver was tested with a DFRobot SHT10 Temperature and
+   * Humidity sensor.  This driver should work on all SHT1X devices.
+   *
+   * It requires a 10K pull-up resistor connected to the data pin.
+   * The sensor can be run at differing voltages from 2.5v to 5v.
+   *
+   * @snippet sht1x.cxx Interesting
+   */
+
+  class SHT1X {
+  public:
+
+    /**
+     * SHT1X object constructor
+     *
+     * @param clk_pin Specify the GPIO pin to use for the clock.
+     * @param data_pin Specify the GPIO pin to use for data.
+     */
+    SHT1X(unsigned int clk_pin, unsigned int data_pin);
+
+    /**
+     * SHT1X object destructor
+     */
+    ~SHT1X();
+
+    /**
+     * Perform a soft reset of the device.
+     */
+    void reset();
+
+    /**
+     * Query the device and store the latest values.  You must call this
+     * function before querying the temperature or the humidity.
+     */
+    void update();
+
+    /**
+     * Query the temperature in degrees Celsius.  update() must have
+     * been called prior to calling this function.
+     *
+     * @return The temperature in Celsius
+     */
+    float getTemperature();
+
+    /**
+     * Query the relative humidity.  update() must have been called
+     * prior to calling this function.
+     *
+     * @return The relative humidity.
+     */
+    float getHumidity();
+
+    /**
+     * Read the status register.
+     *
+     * @return The contents of the status register.
+     */
+    uint8_t readStatus();
+
+    /**
+     * Write a value to the status register.
+     *
+     * @param status The uint8_t to write to the register.
+     * @return UPM result
+     */
+    upm_result_t writeStatus(uint8_t status);
+
+    /**
+     * The Vdd voltage the sensor is being driven at can affect the
+     * temperature measurements.  This function allows you to specify a
+     * voltage as close as you are using to power the sensor, so that
+     * the appropriate compensation can be made.  By default, the
+     * coefficients are set for 5v operation.
+     *
+     * @param volts One of the SHT1X_VOLTS_T values.
+     */
+    void setVolts(SHT1X_VOLTS_T volts);
+
+  protected:
+    // device context
+    sht1x_context m_sht1x;
+
+    /**
+     * Send a command to the device.  This is a low level command that
+     * should not be used directly unless you know exactly what you are
+     * doing.
+     *
+     * @param cmd One of the SHT1X_CMD_T values.
+     * @return UPM result
+     */
+    upm_result_t sendCommand(SHT1X_CMD_T cmd);
+
+    /**
+     * Wait for the appropriate response when starting a temperature or
+     * humidity measurement.  This is a low level command that should
+     * not be used directly unless you know exactly what you are doing.
+     *
+     * @return UPM result
+     */
+    upm_result_t waitForResponse();
+
+    /**
+     * Issue the start transmission sequence.  This is a low level
+     * command that should not be used directly unless you know exactly
+     * what you are doing.
+     *
+     * @return UPM result
+     */
+    void startXmit();
+
+    /**
+     * Read 8 bits (a byte) from the device.  This is a low level
+     * command that should not be used directly unless you know exactly
+     * what you are doing.
+     *
+     * @param value Pointer to a uint8_t that will hold the received byte.
+     * @return UPM result
+     */
+    uint8_t read8Bits();
+
+    /**
+     * Write 8 bits (a byte) to the device.  This is a low level command
+     * that should not be used directly unless you know exactly what you
+     * are doing.
+     *
+     * @param value A uint8_t that will be sent to the device.
+     * @return UPM result
+     */
+    upm_result_t write8Bits(uint8_t byte);
+
+  private:
+  };
+}