hdc-1000-sensor.c

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/*
 * Copyright (c) 2014, Texas Instruments Incorporated - http://www.ti.com/
 * 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.
 */
/*---------------------------------------------------------------------------*/
/**
 * \addtogroup sensortag-cc26xx-hdc-sensor
 * @{
 *
 * \file
 *  Driver for the Sensortag-CC26xx HDC sensor
 */
/*---------------------------------------------------------------------------*/
#include "contiki-conf.h"
#include "sys/ctimer.h"
#include "lib/sensors.h"
#include "hdc-1000-sensor.h"
#include "sensor-common.h"
#include "board-i2c.h"

#include "ti-lib.h"

#include <stdint.h>
#include <string.h>
#include <stdbool.h>
#include <stdio.h>
/*---------------------------------------------------------------------------*/
#define DEBUG 0
#if DEBUG
#define PRINTF(...) printf(__VA_ARGS__)
#else
#define PRINTF(...)
#endif
/*---------------------------------------------------------------------------*/
/* Sensor I2C address */
#define SENSOR_I2C_ADDRESS         0x43

/* Registers */
#define HDC1000_REG_TEMP           0x00 /* Temperature */
#define HDC1000_REG_HUM            0x01 /* Humidity */
#define HDC1000_REG_CONFIG         0x02 /* Configuration */
#define HDC1000_REG_SERID_H        0xFB /* Serial ID high */
#define HDC1000_REG_SERID_M        0xFC /* Serial ID middle */
#define HDC1000_REG_SERID_L        0xFD /* Serial ID low */
#define HDC1000_REG_MANF_ID        0xFE /* Manufacturer ID */
#define HDC1000_REG_DEV_ID         0xFF /* Device ID */

/* Fixed values */
#define HDC1000_VAL_MANF_ID        0x5449
#define HDC1000_VAL_DEV_ID         0x1000
#define HDC1000_VAL_CONFIG         0x1000 /* 14 bit, acquired in sequence */

/* Sensor selection/deselection */
#define SENSOR_SELECT()     board_i2c_select(BOARD_I2C_INTERFACE_0, SENSOR_I2C_ADDRESS)
#define SENSOR_DESELECT()   board_i2c_deselect()
/*---------------------------------------------------------------------------*/
/* Byte swap of 16-bit register value */
#define HI_UINT16(a) (((a) >> 8) & 0xFF)
#define LO_UINT16(a) ((a) & 0xFF)

#define SWAP(v) ((LO_UINT16(v) << 8) | HI_UINT16(v))
/*---------------------------------------------------------------------------*/
/* Raw data as returned from the sensor (Big Endian) */
typedef struct sensor_data {
  uint16_t temp;
  uint16_t hum;
} sensor_data_t;

/* Raw data, little endian */
static uint16_t raw_temp;
static uint16_t raw_hum;
/*---------------------------------------------------------------------------*/
static bool success;
static sensor_data_t data;
/*---------------------------------------------------------------------------*/
static int enabled = HDC_1000_SENSOR_STATUS_DISABLED;
/*---------------------------------------------------------------------------*/
/*
 * Maximum measurement durations in clock ticks. We use 14bit resolution, thus:
 * - Tmp: 6.35ms
 * - RH:  6.5ms
 */
#define MEASUREMENT_DURATION 2

/*
 * Wait SENSOR_STARTUP_DELAY clock ticks between activation and triggering a
 * reading (max 15ms)
 */
#define SENSOR_STARTUP_DELAY 3

static struct ctimer startup_timer;
/*---------------------------------------------------------------------------*/
/**
 * \brief       Initialise the humidity sensor driver
 * \return      True if I2C operation successful
 */
static bool
sensor_init(void)
{
  uint16_t val;

  SENSOR_SELECT();

  /* Enable reading data in one operation */
  val = SWAP(HDC1000_VAL_CONFIG);
  success = sensor_common_write_reg(HDC1000_REG_CONFIG, (uint8_t *)&val, 2);

  SENSOR_DESELECT();

  return success;
}
/*---------------------------------------------------------------------------*/
/**
 * \brief       Start measurement
 */
static void
start(void)
{
  if(success) {
    SENSOR_SELECT();

    success = board_i2c_write_single(HDC1000_REG_TEMP);
    SENSOR_DESELECT();
  }
}
/*---------------------------------------------------------------------------*/
/**
 * \brief       Take readings from the sensor
 * \return      true of I2C operations successful
 */
static bool
read_data()
{
  bool valid;

  if(success) {
    SENSOR_SELECT();

    success = board_i2c_read((uint8_t *)&data, sizeof(data));
    SENSOR_DESELECT();

    /* Store temperature */
    raw_temp = SWAP(data.temp);

    /* Store humidity */
    raw_hum = SWAP(data.hum);
  }

  valid = success;
  success = true;

  return valid;
}
/*---------------------------------------------------------------------------*/
/**
 * \brief       Convert raw data to temperature and humidity
 * \param       temp - converted temperature
 * \param       hum - converted humidity
 */
static void
convert(float *temp, float *hum)
{
  /* Convert temperature to degrees C */
  *temp = ((double)(int16_t)raw_temp / 65536) * 165 - 40;

  /* Convert relative humidity to a %RH value */
  *hum = ((double)raw_hum / 65536) * 100;
}
/*---------------------------------------------------------------------------*/
static void
notify_ready(void *not_used)
{
  enabled = HDC_1000_SENSOR_STATUS_READINGS_READY;

  /* Latch readings */
  read_data();

  sensors_changed(&hdc_1000_sensor);
}
/*---------------------------------------------------------------------------*/
/**
 * \brief Returns a reading from the sensor
 * \param type HDC_1000_SENSOR_TYPE_TEMP or HDC_1000_SENSOR_TYPE_HUMIDITY
 * \return Temperature (centi degrees C) or Humidity (centi %RH)
 */
static int
value(int type)
{
  int rv;
  float temp;
  float hum;

  if(enabled != HDC_1000_SENSOR_STATUS_READINGS_READY) {
    PRINTF("Sensor disabled or starting up (%d)\n", enabled);
    return CC26XX_SENSOR_READING_ERROR;
  }

  if((type != HDC_1000_SENSOR_TYPE_TEMP) &&
     type != HDC_1000_SENSOR_TYPE_HUMIDITY) {
    PRINTF("Invalid type\n");
    return CC26XX_SENSOR_READING_ERROR;
  } else {
    convert(&temp, &hum);
    PRINTF("HDC: %04X %04X       t=%d h=%d\n", raw_temp, raw_hum,
           (int)(temp * 100), (int)(hum * 100));

    if(type == HDC_1000_SENSOR_TYPE_TEMP) {
      rv = (int)(temp * 100);
    } else if(type == HDC_1000_SENSOR_TYPE_HUMIDITY) {
      rv = (int)(hum * 100);
    }
  }
  return rv;
}
/*---------------------------------------------------------------------------*/
/**
 * \brief Configuration function for the HDC1000 sensor.
 *
 * \param type Activate, enable or disable the sensor. See below
 * \param enable
 *
 * When type == SENSORS_HW_INIT we turn on the hardware
 * When type == SENSORS_ACTIVE and enable==1 we enable the sensor
 * When type == SENSORS_ACTIVE and enable==0 we disable the sensor
 */
static int
configure(int type, int enable)
{
  switch(type) {
  case SENSORS_HW_INIT:
    raw_temp = 0;
    raw_hum = 0;
    memset(&data, 0, sizeof(data));

    sensor_init();
    enabled = HDC_1000_SENSOR_STATUS_INITIALISED;
    break;
  case SENSORS_ACTIVE:
    /* Must be initialised first */
    if(enabled == HDC_1000_SENSOR_STATUS_DISABLED) {
      return HDC_1000_SENSOR_STATUS_DISABLED;
    }
    if(enable) {
      start();
      ctimer_set(&startup_timer, SENSOR_STARTUP_DELAY, notify_ready, NULL);
      enabled = HDC_1000_SENSOR_STATUS_TAKING_READINGS;
    } else {
      ctimer_stop(&startup_timer);
      enabled = HDC_1000_SENSOR_STATUS_INITIALISED;
    }
    break;
  default:
    break;
  }
  return enabled;
}
/*---------------------------------------------------------------------------*/
/**
 * \brief Returns the status of the sensor
 * \param type SENSORS_ACTIVE or SENSORS_READY
 * \return One of the SENSOR_STATUS_xyz defines
 */
static int
status(int type)
{
  switch(type) {
  case SENSORS_ACTIVE:
  case SENSORS_READY:
    return enabled;
    break;
  default:
    break;
  }
  return HDC_1000_SENSOR_STATUS_DISABLED;
}
/*---------------------------------------------------------------------------*/
SENSORS_SENSOR(hdc_1000_sensor, "HDC1000", value, configure, status);
/*---------------------------------------------------------------------------*/
/** @} */