File content as of revision 7:653f782ce3aa:

/**************************************************************************/
/*!
    @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, 1); // no stop
    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 = ADS1115_CONVERSIONDELAY_860SPS;
    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_860SPS;
    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)
                      ADS1115_REG_CONFIG_DR_860SPS    | // 860 Samples per Second, ADS1115
                      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);
}
 
/**************************************************************************/
/*!
    @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(ADS1015) or 250(ADS1115) 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(ADS1015) or 250(ADS1115) 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(ADS1015) or 250(ADS1115) 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;
    }
}