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RIOT/drivers/mq3/mq3.c 1006 Bytes
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  /*
   * Copyright (C) 2014 Freie Universitรคt Berlin
   *
   * This file is subject to the terms and conditions of the GNU Lesser General
   * Public License v2.1. See the file LICENSE in the top level directory for more
   * details.
   */
  
  /**
   * @ingroup     drivers_mq3
   * @{
   *
   * @file
   * @brief       Device driver implementation for the MQ-3 alcohol sensor
   *
   * @author      Hauke Petersen <hauke.petersen@fu-berlin.de>
   *
   * @}
   */
  
  #include "mq3.h"
  
  #define PRECISION           ADC_RES_10BIT
  #define MIN                 (100U)              /* TODO: calibrate to useful value */
  #define FACTOR              (2.33f)             /* TODO: calibrate to useful value */
  
  int mq3_init(mq3_t *dev, adc_t adc_line)
  {
      dev->adc_line = adc_line;
      return adc_init(dev->adc_line);
  }
  
  int mq3_read_raw(const mq3_t *dev)
  {
      return adc_sample(dev->adc_line, PRECISION);
  }
  
  int mq3_read(const mq3_t *dev)
  {
      float res = mq3_read_raw(dev);
      res = (res > MIN) ? res - MIN : 0;
      return (int)(res * FACTOR);
  }