/* * Driver for Sensirion SHT3x digital temperature and humidity sensor * connected to I2C * * Part of esp-open-rtos * * ---------------------------------------------------------------- * * The BSD License (3-clause license) * * Copyright (c) 2017 Gunar Schorcht (https://github.com/gschorcht * All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions are met: * * 1. Redistributions of source code must retain the above copyright notice, * this list of conditions and the following disclaimer. * * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * * 3. Neither the name of the copyright holder nor the names of its * contributors may be used to endorse or promote products derived from this * software without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE * POSSIBILITY OF SUCH DAMAGE. */ #ifndef DRIVER_SHT3x_H_ #define DRIVER_SHT3x_H_ #include "stdint.h" #include "stdbool.h" #include "FreeRTOS.h" #include "i2c/i2c.h" // Uncomment to enable debug output // #define SHT3x_DEBUG_LEVEL_1 // only error messages // #define SHT3x_DEBUG_LEVEL_2 // error and debug messages #ifdef __cplusplus extern "C" { #endif // definition of possible I2C slave addresses #define SHT3x_ADDR_1 0x44 // ADDR pin connected to GND/VSS (default) #define SHT3x_ADDR_2 0x45 // ADDR pin connected to VDD // definition of error codes #define SHT3x_OK 0 #define SHT3x_NOK -1 #define SHT3x_I2C_ERROR_MASK 0x000f #define SHT3x_DRV_ERROR_MASK 0xfff0 // error codes for I2C interface ORed with SHT3x error codes #define SHT3x_I2C_READ_FAILED 1 #define SHT3x_I2C_SEND_CMD_FAILED 2 #define SHT3x_I2C_BUSY 3 // SHT3x driver error codes OR ed with error codes for I2C interface #define SHT3x_MEAS_NOT_STARTED (1 << 8) #define SHT3x_MEAS_ALREADY_RUNNING (2 << 8) #define SHT3x_MEAS_STILL_RUNNING (3 << 8) #define SHT3x_READ_RAW_DATA_FAILED (4 << 8) #define SHT3x_SEND_MEAS_CMD_FAILED (5 << 8) #define SHT3x_SEND_RESET_CMD_FAILED (6 << 8) #define SHT3x_SEND_STATUS_CMD_FAILED (7 << 8) #define SHT3x_SEND_FETCH_CMD_FAILED (8 << 8) #define SHT3x_WRONG_CRC_TEMPERATURE (9 << 8) #define SHT3x_WRONG_CRC_HUMIDITY (10 << 8) #define SHT3x_RAW_DATA_SIZE 6 /** * @brief raw data type */ typedef uint8_t sht3x_raw_data_t [SHT3x_RAW_DATA_SIZE]; /** * @brief possible measurement modes */ typedef enum { sht3x_single_shot = 0, // one single measurement sht3x_periodic_05mps, // periodic with 0.5 measurements per second (mps) sht3x_periodic_1mps, // periodic with 1 measurements per second (mps) sht3x_periodic_2mps, // periodic with 2 measurements per second (mps) sht3x_periodic_4mps, // periodic with 4 measurements per second (mps) sht3x_periodic_10mps // periodic with 10 measurements per second (mps) } sht3x_mode_t; /** * @brief possible repeatability modes */ typedef enum { sht3x_high = 0, sht3x_medium, sht3x_low } sht3x_repeat_t; /** * @brief SHT3x sensor device data structure type */ typedef struct { uint32_t error_code; // combined error codes uint8_t bus; // I2C bus at which sensor is connected uint8_t addr; // I2C slave address of the sensor sht3x_mode_t mode; // used measurement mode sht3x_repeat_t repeatability; // used repeatability bool meas_started; // indicates whether measurement started uint32_t meas_start_time; // measurement start time in us bool meas_first; // first measurement in periodic mode } sht3x_sensor_t; /** * @brief Initialize a SHT3x sensor * * The function creates a data structure describing the sensor and * initializes the sensor device. * * @param bus I2C bus at which the sensor is connected * @param addr I2C slave address of the sensor * @return pointer to sensor data structure, or NULL on error */ sht3x_sensor_t* sht3x_init_sensor (uint8_t bus, uint8_t addr); /** * @brief High level measurement function * * For convenience this function comprises all three steps to perform * one measurement in only one function: * * 1. Starts a measurement in single shot mode with high reliability * 2. Waits using *vTaskDelay* until measurement results are available * 3. Returns the results in kind of floating point sensor values * * This function is the easiest way to use the sensor. It is most suitable * for users that don't want to have the control on sensor details. * * Please note: The function delays the calling task up to 30 ms to wait for * the the measurement results. This might lead to problems when the function * is called from a software timer callback function. * * @param dev pointer to sensor device data structure * @param temperature returns temperature in degree Celsius * @param humidity returns humidity in percent * @return true on success, false on error */ bool sht3x_measure (sht3x_sensor_t* dev, float* temperature, float* humidity); /** * @brief Start the measurement in single shot or periodic mode * * The function starts the measurement either in *single shot mode* * (exactly one measurement) or *periodic mode* (periodic measurements) * with given repeatabilty. * * In the *single shot mode*, this function has to be called for each * measurement. The measurement duration has to be waited every time * before the results can be fetched. * * In the *periodic mode*, this function has to be called only once. Also * the measurement duration has to be waited only once until the first * results are available. After this first measurement, the sensor then * automatically performs all subsequent measurements. The rate of periodic * measurements can be 10, 4, 2, 1 or 0.5 measurements per second (mps). * * Please note: Due to inaccuracies in timing of the sensor, the user task * should fetch the results at a lower rate. The rate of the periodic * measurements is defined by the parameter *mode*. * * @param dev pointer to sensor device data structure * @param mode measurement mode, see type *sht3x_mode_t* * @param repeat repeatability, see type *sht3x_repeat_t* * @return true on success, false on error */ bool sht3x_start_measurement (sht3x_sensor_t* dev, sht3x_mode_t mode, sht3x_repeat_t repeat); /** * @brief Get the duration of a measurement in RTOS ticks. * * The function returns the duration in RTOS ticks required by the sensor to * perform a measurement for the given repeatability. Once a measurement is * started with function *sht3x_start_measurement* the user task can use this * duration in RTOS ticks directly to wait with function *vTaskDelay* until * the measurement results can be fetched. * * Please note: The duration only depends on repeatability level. Therefore, * it can be considered as constant for a repeatibility. * * @param repeat repeatability, see type *sht3x_repeat_t* * @return measurement duration given in RTOS ticks */ uint8_t sht3x_get_measurement_duration (sht3x_repeat_t repeat); /** * @brief Read measurement results from sensor as raw data * * The function read measurement results from the sensor, checks the CRC * checksum and stores them in the byte array as following. * * data[0] = Temperature MSB * data[1] = Temperature LSB * data[2] = Temperature CRC * data[3] = Pressure MSB * data[4] = Pressure LSB * data[2] = Pressure CRC * * In case that there are no new data that can be read, the function fails. * * @param dev pointer to sensor device data structure * @param raw_data byte array in which raw data are stored * @return true on success, false on error */ bool sht3x_get_raw_data(sht3x_sensor_t* dev, sht3x_raw_data_t raw_data); /** * @brief Computes sensor values from raw data * * @param raw_data byte array that contains raw data * @param temperature returns temperature in degree Celsius * @param humidity returns humidity in percent * @return true on success, false on error */ bool sht3x_compute_values (sht3x_raw_data_t raw_data, float* temperature, float* humidity); /** * @brief Get measurement results in form of sensor values * * The function combines function *sht3x_read_raw_data* and function * *sht3x_compute_values* to get the measurement results. * * In case that there are no results that can be read, the function fails. * * @param dev pointer to sensor device data structure * @param temperature returns temperature in degree Celsius * @param humidity returns humidity in percent * @return true on success, false on error */ bool sht3x_get_results (sht3x_sensor_t* dev, float* temperature, float* humidity); #ifdef __cplusplus } #endif #endif /* DRIVER_SHT3x_H_ */