File content as of revision 0:8174d9ceeca1:

/**************************************************************************/
/*!
    @file     Adafruit_ADS1015.cpp
    @author   K.Townsend (Adafruit Industries)
    @license  BSD (see LICENSE.txt)

    Ported to mbed by Arve Seljebu - arve0.github.io

    Driver for the ADS1015/ADS1115 ADC

    This is a library for the Adafruit MPL115A2 breakout
    ----> https://www.adafruit.com/products/1083

    Adafruit invests time and resources providing this open source code,
    please support Adafruit and open-source hardware by purchasing
    products from Adafruit!

    @section  HISTORY

    v1.0 - First release
    v1.1.1 - Ported to mbed
*/
/**************************************************************************/

#include <mbed.h>
#include "Adafruit_ADS1015.h"

/**************************************************************************/
/*!
    @brief  Writes 16-bits to the specified destination register
*/
/**************************************************************************/
void Adafruit_ADS1015::writeRegister(uint8_t i2cAddress, uint8_t reg, uint16_t value) {
  char cmd[3];
  cmd[0] = (char)reg;
  cmd[1] = (char)(value>>8);
  cmd[2] = (char)(value & 0xFF);
  m_i2c->write(i2cAddress, cmd, 3); 
}

/**************************************************************************/
/*!
    @brief  Reads 16-bits from the specified register
*/
/**************************************************************************/
uint16_t Adafruit_ADS1015::readRegister(uint8_t i2cAddress, uint8_t reg) {
  char data[2];
  data[0] = reg; // temporary use this to send address to conversion register
  m_i2c->write(i2cAddress, data, 1);
  m_i2c->read(i2cAddress, data, 2);
  return (data[0] << 8 | data [1]);
}

/**************************************************************************/
/*!
    @brief  Instantiates a new ADS1015 class w/appropriate properties
*/
/**************************************************************************/
Adafruit_ADS1015::Adafruit_ADS1015(I2C* i2c, uint8_t i2cAddress) 
{
  // shift 7 bit address 1 left: read expects 8 bit address, see I2C.h
   m_i2cAddress = i2cAddress << 1;
   m_conversionDelay = ADS1015_CONVERSIONDELAY;
   m_bitShift = 4;
   m_gain = GAIN_TWOTHIRDS; /* +/- 6.144V range (limited to VDD +0.3V max!) */
   m_i2c = i2c;
}

/**************************************************************************/
/*!
    @brief  Instantiates a new ADS1115 class w/appropriate properties
*/
/**************************************************************************/
Adafruit_ADS1115::Adafruit_ADS1115(I2C* i2c, uint8_t i2cAddress)
{
  // shift 7 bit address 1 left: read expects 8 bit address, see mbed's I2C.h
  m_i2cAddress = i2cAddress << 1;
  m_conversionDelay = ADS1115_CONVERSIONDELAY;
  m_bitShift = 0;
  m_gain = GAIN_TWOTHIRDS; /* +/- 6.144V range (limited to VDD +0.3V max!) */
  m_i2c = i2c;
}

/**************************************************************************/
/*!
    @brief  Sets the gain and input voltage range
*/
/**************************************************************************/
void Adafruit_ADS1015::setGain(adsGain_t gain)
{
  m_gain = gain;
}

/**************************************************************************/
/*!
    @brief  Gets a gain and input voltage range
*/
/**************************************************************************/
adsGain_t Adafruit_ADS1015::getGain()
{
  return m_gain;
}

/**************************************************************************/
/*!
    @brief  Gets a single-ended ADC reading from the specified channel
*/
/**************************************************************************/
uint16_t Adafruit_ADS1015::readADC_SingleEnded(uint8_t channel) {
  if (channel > 3)
  {
    return 0;
  }
  
  // Start with default values
  uint16_t config = ADS1015_REG_CONFIG_CQUE_NONE    | // Disable the comparator (default val)
                    ADS1015_REG_CONFIG_CLAT_NONLAT  | // Non-latching (default val)
                    ADS1015_REG_CONFIG_CPOL_ACTVLOW | // Alert/Rdy active low   (default val)
                    ADS1015_REG_CONFIG_CMODE_TRAD   | // Traditional comparator (default val)
                    ADS1015_REG_CONFIG_DR_1600SPS   | // 1600 samples per second (default)
                    ADS1015_REG_CONFIG_MODE_SINGLE;   // Single-shot mode (default)

  // Set PGA/voltage range
  config |= m_gain;

  // Set single-ended input channel
  switch (channel)
  {
    case (0):
      config |= ADS1015_REG_CONFIG_MUX_SINGLE_0;
      break;
    case (1):
      config |= ADS1015_REG_CONFIG_MUX_SINGLE_1;
      break;
    case (2):
      config |= ADS1015_REG_CONFIG_MUX_SINGLE_2;
      break;
    case (3):
      config |= ADS1015_REG_CONFIG_MUX_SINGLE_3;
      break;
  }

  // Set 'start single-conversion' bit
  config |= ADS1015_REG_CONFIG_OS_SINGLE;

  // Write config register to the ADC
  writeRegister(m_i2cAddress, ADS1015_REG_POINTER_CONFIG, config);

  // Wait for the conversion to complete
  wait_ms(m_conversionDelay);

  // Read the conversion results
  // Shift 12-bit results right 4 bits for the ADS1015
  return readRegister(m_i2cAddress, ADS1015_REG_POINTER_CONVERT) >> m_bitShift;  
}

/**************************************************************************/
/*! 
    @brief  Reads the conversion results, measuring the voltage
            difference between the P (AIN0) and N (AIN1) input.  Generates
            a signed value since the difference can be either
            positive or negative.
*/
/**************************************************************************/
int16_t Adafruit_ADS1015::readADC_Differential_0_1() {
  // Start with default values
  uint16_t config = ADS1015_REG_CONFIG_CQUE_NONE    | // Disable the comparator (default val)
                    ADS1015_REG_CONFIG_CLAT_NONLAT  | // Non-latching (default val)
                    ADS1015_REG_CONFIG_CPOL_ACTVLOW | // Alert/Rdy active low   (default val)
                    ADS1015_REG_CONFIG_CMODE_TRAD   | // Traditional comparator (default val)
                    ADS1015_REG_CONFIG_DR_1600SPS   | // 1600 samples per second (default)
                    ADS1015_REG_CONFIG_MODE_SINGLE;   // Single-shot mode (default)

  // Set PGA/voltage range
  config |= m_gain;
                    
  // Set channels
  config |= ADS1015_REG_CONFIG_MUX_DIFF_0_1;          // AIN0 = P, AIN1 = N

  // Set 'start single-conversion' bit
  config |= ADS1015_REG_CONFIG_OS_SINGLE;

  // Write config register to the ADC
  writeRegister(m_i2cAddress, ADS1015_REG_POINTER_CONFIG, config);

  // Wait for the conversion to complete
  wait_ms(m_conversionDelay);

  // Read the conversion results
  uint16_t res = readRegister(m_i2cAddress, ADS1015_REG_POINTER_CONVERT) >> m_bitShift;
  if (m_bitShift == 0)
  {
    return (int16_t)res;
  }
  else
  {
    // Shift 12-bit results right 4 bits for the ADS1015,
    // making sure we keep the sign bit intact
    if (res > 0x07FF)
    {
      // negative number - extend the sign to 16th bit
      res |= 0xF000;
    }
    return (int16_t)res;
  }
}

/**************************************************************************/
/*! 
    @brief  Reads the conversion results, measuring the voltage
            difference between the P (AIN2) and N (AIN3) input.  Generates
            a signed value since the difference can be either
            positive or negative.
*/
/**************************************************************************/
int16_t Adafruit_ADS1015::readADC_Differential_2_3() {
  // Start with default values
  uint16_t config = ADS1015_REG_CONFIG_CQUE_NONE    | // Disable the comparator (default val)
                    ADS1015_REG_CONFIG_CLAT_NONLAT  | // Non-latching (default val)
                    ADS1015_REG_CONFIG_CPOL_ACTVLOW | // Alert/Rdy active low   (default val)
                    ADS1015_REG_CONFIG_CMODE_TRAD   | // Traditional comparator (default val)
                    ADS1015_REG_CONFIG_DR_1600SPS   | // 1600 samples per second (default)
                    ADS1015_REG_CONFIG_MODE_SINGLE;   // Single-shot mode (default)

  // Set PGA/voltage range
  config |= m_gain;

  // Set channels
  config |= ADS1015_REG_CONFIG_MUX_DIFF_2_3;          // AIN2 = P, AIN3 = N

  // Set 'start single-conversion' bit
  config |= ADS1015_REG_CONFIG_OS_SINGLE;

  // Write config register to the ADC
  writeRegister(m_i2cAddress, ADS1015_REG_POINTER_CONFIG, config);

  // Wait for the conversion to complete
  wait_ms(m_conversionDelay);

  // Read the conversion results
  uint16_t res = readRegister(m_i2cAddress, ADS1015_REG_POINTER_CONVERT) >> m_bitShift;
  if (m_bitShift == 0)
  {
    return (int16_t)res;
  }
  else
  {
    // Shift 12-bit results right 4 bits for the ADS1015,
    // making sure we keep the sign bit intact
    if (res > 0x07FF)
    {
      // negative number - extend the sign to 16th bit
      res |= 0xF000;
    }
    return (int16_t)res;
  }
}

/**************************************************************************/
/*!
    @brief  Sets up the comparator to operate in basic mode, causing the
            ALERT/RDY pin to assert (go from high to low) when the ADC
            value exceeds the specified threshold.

            This will also set the ADC in continuous conversion mode.
*/
/**************************************************************************/
void Adafruit_ADS1015::startComparator_SingleEnded(uint8_t channel, int16_t threshold)
{
  // Start with default values
  uint16_t config = ADS1015_REG_CONFIG_CQUE_1CONV   | // Comparator enabled and asserts on 1 match
                    ADS1015_REG_CONFIG_CLAT_LATCH   | // Latching mode
                    ADS1015_REG_CONFIG_CPOL_ACTVLOW | // Alert/Rdy active low   (default val)
                    ADS1015_REG_CONFIG_CMODE_TRAD   | // Traditional comparator (default val)
                    ADS1015_REG_CONFIG_DR_1600SPS   | // 1600 samples per second (default)
                    ADS1015_REG_CONFIG_MODE_CONTIN  | // Continuous conversion mode
                    ADS1015_REG_CONFIG_MODE_CONTIN;   // Continuous conversion mode

  // Set PGA/voltage range
  config |= m_gain;
                    
  // Set single-ended input channel
  switch (channel)
  {
    case (0):
      config |= ADS1015_REG_CONFIG_MUX_SINGLE_0;
      break;
    case (1):
      config |= ADS1015_REG_CONFIG_MUX_SINGLE_1;
      break;
    case (2):
      config |= ADS1015_REG_CONFIG_MUX_SINGLE_2;
      break;
    case (3):
      config |= ADS1015_REG_CONFIG_MUX_SINGLE_3;
      break;
  }

  // Set the high threshold register
  // Shift 12-bit results left 4 bits for the ADS1015
  writeRegister(m_i2cAddress, ADS1015_REG_POINTER_HITHRESH, threshold << m_bitShift);

  // Write config register to the ADC
  writeRegister(m_i2cAddress, ADS1015_REG_POINTER_CONFIG, config);
}

/**************************************************************************/
/*!
    @brief  In order to clear the comparator, we need to read the
            conversion results.  This function reads the last conversion
            results without changing the config value.
*/
/**************************************************************************/
int16_t Adafruit_ADS1015::getLastConversionResults()
{
  // Wait for the conversion to complete
  wait_ms(m_conversionDelay);

  // Read the conversion results
  uint16_t res = readRegister(m_i2cAddress, ADS1015_REG_POINTER_CONVERT) >> m_bitShift;
  if (m_bitShift == 0)
  {
    return (int16_t)res;
  }
  else
  {
    // Shift 12-bit results right 4 bits for the ADS1015,
    // making sure we keep the sign bit intact
    if (res > 0x07FF)
    {
      // negative number - extend the sign to 16th bit
      res |= 0xF000;
    }
    return (int16_t)res;
  }
}