adc-sensor.c

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/*
 * Copyright (c) 2011, George Oikonomou - <oikonomou@users.sourceforge.net>
 * 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 Institute 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 INSTITUTE 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 INSTITUTE 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.
 *
 * This file is part of the Contiki operating system.
 */

/**
 * \file
 *         ADC sensor module for TI SmartRF05EB devices.
 *
 * \author
 *         George Oikonomou - <oikonomou@users.sourceforge.net>
 */
#include "sfr-bits.h"
#include "cc253x.h"
#include "adc-sensor.h"

#if ADC_SENSOR_ON
/*---------------------------------------------------------------------------*/
static int
value(int type)
{
  uint16_t reading;
  /*
   * For single-shot AD conversions, we may only write to ADCCON3[3:0] once
   * (This write triggers the conversion). We thus use the variable 'command'
   * to store intermediate steps (reference, decimation rate, input channel)
   */
  uint8_t command;

  /* 1.25V ref, max decimation rate */
  command = ADCCON3_EDIV1 | ADCCON3_EDIV0;

  /* Clear the Interrupt Flag */
  ADCIF = 0;

  /* Depending on the desired reading, append the input bits to 'command' and
   * enable the corresponding input channel in ADCCFG if necessary */
  switch(type) {
#if TEMP_SENSOR_ON
  case ADC_SENSOR_TYPE_TEMP:
    command |= ADCCON3_ECH3 | ADCCON3_ECH2 | ADCCON3_ECH1;
    break;
#endif
#if VDD_SENSOR_ON
  case ADC_SENSOR_TYPE_VDD:
    command |= ADCCON3_ECH3 | ADCCON3_ECH2 | ADCCON3_ECH1 | ADCCON3_ECH0;
    break;
#endif
  default:
    /* If the sensor is not present or disabled in conf, return -1 */
    return -1;
  }

  /* Writing in bits 3:0 of ADCCON3 will trigger a single conversion */
  ADCCON3 = command;

  /*
   * When the conversion is complete, the ADC interrupt flag is set. We don't
   * use an ISR here, we just wait on the flag and clear it afterwards.
   */
  while(!ADCIF);

  /* Clear the Interrupt Flag */
  ADCIF = 0;

  reading = ADCL;
  reading |= (((uint8_t) ADCH) << 8);
  /* 12-bit decimation rate: 4 LS bits are noise */
  reading >>= 4;

  return reading;
}
/*---------------------------------------------------------------------------*/
static int
status(int type)
{
  return 1;
}
/*---------------------------------------------------------------------------*/
static int
configure(int type, int value)
{
  switch(type) {
  case SENSORS_HW_INIT:
#if TEMP_SENSOR_ON
    /* Connect temperature sensor to the SoC */
    ATEST = 1;
    TESTREG0 = 1;
#endif
    APCFG = 0; /* Disables Input Channels */
    break;
  }
  return 1;
}
/*---------------------------------------------------------------------------*/
SENSORS_SENSOR(adc_sensor, ADC_SENSOR, value, configure, status);
#endif /* ADC_SENSOR_ON */