INA226.cpp

/*
INA226.cpp - Class file for the INA226 Bi-directional Current/Power Monitor Arduino Library.

Version: 1.0.0
(c) 2014 Korneliusz Jarzebski
www.jarzebski.pl

This program is free software: you can redistribute it and/or modify
it under the terms of the version 3 GNU General Public License as
published by the Free Software Foundation.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/

#if ARDUINO >= 100
#include "Arduino.h"
#else
#include "WProgram.h"
#endif

#include <Wire.h>

#include "INA226.h"

bool INA226::begin(uint8_t address)
{
    Wire.begin();
    inaAddress = address;
    return true;
}

bool INA226::configure(ina226_averages_t avg, ina226_busConvTime_t busConvTime, ina226_shuntConvTime_t shuntConvTime, ina226_mode_t mode)
{
    uint16_t config = 0;

    config |= (avg << 9 | busConvTime << 6 | shuntConvTime << 3 | mode);

    vBusMax = 36;
    vShuntMax = 0.08192f;

    writeRegister16(INA226_REG_CONFIG, config);

    return true;
}

bool INA226::calibrate(float rShuntValue, float iMaxExpected)
{
    uint16_t calibrationValue;
    rShunt = rShuntValue;

    float iMaxPossible, minimumLSB;

    iMaxPossible = vShuntMax / rShunt;

    minimumLSB = iMaxExpected / 32767;

    currentLSB = (uint16_t)(minimumLSB * 100000000);
    currentLSB /= 100000000;
    currentLSB /= 0.0001;
    currentLSB = ceil(currentLSB);
    currentLSB *= 0.0001;

    powerLSB = currentLSB * 25;

    calibrationValue = (uint16_t)((0.00512) / (currentLSB * rShunt));

    writeRegister16(INA226_REG_CALIBRATION, calibrationValue);

    return true;
}

float INA226::getMaxPossibleCurrent(void)
{
    return (vShuntMax / rShunt);
}

float INA226::getMaxCurrent(void)
{
    float maxCurrent = (currentLSB * 32767);
    float maxPossible = getMaxPossibleCurrent();

    if (maxCurrent > maxPossible)
    {
        return maxPossible;
    } else
    {
        return maxCurrent;
    }
}

float INA226::getMaxShuntVoltage(void)
{
    float maxVoltage = getMaxCurrent() * rShunt;

    if (maxVoltage >= vShuntMax)
    {
        return vShuntMax;
    } else
    {
        return maxVoltage;
    }
}

float INA226::getMaxPower(void)
{
    return (getMaxCurrent() * vBusMax);
}

float INA226::readBusPower(void)
{
    return (readRegister16(INA226_REG_POWER) * powerLSB);
}

float INA226::readShuntCurrent(void)
{
    return (readRegister16(INA226_REG_CURRENT) * currentLSB);
}

float INA226::readShuntVoltage(void)
{
    float voltage;

    voltage = readRegister16(INA226_REG_SHUNTVOLTAGE);

    return (voltage * 0.0000025);
}

float INA226::readBusVoltage(void)
{
    int16_t voltage;

    voltage = readRegister16(INA226_REG_BUSVOLTAGE);

    return (voltage * 0.00125);
}

ina226_averages_t INA226::getAverages(void)
{
    uint16_t value;

    value = readRegister16(INA226_REG_CONFIG);
    value &= 0b0000111000000000;
    value >>= 9;

    return (ina226_averages_t)value;
}

ina226_busConvTime_t INA226::getBusConversionTime(void)
{
    uint16_t value;

    value = readRegister16(INA226_REG_CONFIG);
    value &= 0b0000000111000000;
    value >>= 6;

    return (ina226_busConvTime_t)value;
}

ina226_shuntConvTime_t INA226::getShuntConversionTime(void)
{
    uint16_t value;

    value = readRegister16(INA226_REG_CONFIG);
    value &= 0b0000000000111000;
    value >>= 3;

    return (ina226_shuntConvTime_t)value;
}

ina226_mode_t INA226::getMode(void)
{
    uint16_t value;

    value = readRegister16(INA226_REG_CONFIG);
    value &= 0b0000000000000111;

    return (ina226_mode_t)value;
}

void INA226::setMaskEnable(uint16_t mask)
{
    writeRegister16(INA226_REG_MASKENABLE, mask);
}

uint16_t INA226::getMaskEnable(void)
{
    return readRegister16(INA226_REG_MASKENABLE);
}

void INA226::enableShuntOverLimitAlert(void)
{
    writeRegister16(INA226_REG_MASKENABLE, INA226_BIT_SOL);
}

void INA226::enableShuntUnderLimitAlert(void)
{
    writeRegister16(INA226_REG_MASKENABLE, INA226_BIT_SUL);
}

void INA226::enableBusOvertLimitAlert(void)
{
    writeRegister16(INA226_REG_MASKENABLE, INA226_BIT_BOL);
}

void INA226::enableBusUnderLimitAlert(void)
{
    writeRegister16(INA226_REG_MASKENABLE, INA226_BIT_BUL);
}

void INA226::enableOverPowerLimitAlert(void)
{
    writeRegister16(INA226_REG_MASKENABLE, INA226_BIT_POL);
}

void INA226::enableConversionReadyAlert(void)
{
    writeRegister16(INA226_REG_MASKENABLE, INA226_BIT_CNVR);
}

void INA226::setBusVoltageLimit(float voltage)
{
    uint16_t value = voltage / 0.00125;
    writeRegister16(INA226_REG_ALERTLIMIT, value);
}

void INA226::setShuntVoltageLimit(float voltage)
{
    uint16_t value = voltage * 25000;
    writeRegister16(INA226_REG_ALERTLIMIT, value);
}

void INA226::setPowerLimit(float watts)
{
    uint16_t value = watts / powerLSB;
    writeRegister16(INA226_REG_ALERTLIMIT, value);
}

void INA226::setAlertInvertedPolarity(bool inverted)
{
    uint16_t temp = getMaskEnable();

    if (inverted)
    {
        temp |= INA226_BIT_APOL;
    } else
    {
        temp &= ~INA226_BIT_APOL;
    }

    setMaskEnable(temp);
}

void INA226::setAlertLatch(bool latch)
{
    uint16_t temp = getMaskEnable();

    if (latch)
    {
        temp |= INA226_BIT_LEN;
    } else
    {
        temp &= ~INA226_BIT_LEN;
    }

    setMaskEnable(temp);
}

bool INA226::isMathOverflow(void)
{
    return ((getMaskEnable() & INA226_BIT_OVF) == INA226_BIT_OVF);
}

bool INA226::isAlert(void)
{
    return ((getMaskEnable() & INA226_BIT_AFF) == INA226_BIT_AFF);
}

int16_t INA226::readRegister16(uint8_t reg)
{
    int16_t value;

    Wire.beginTransmission(inaAddress);
    #if ARDUINO >= 100
        Wire.write(reg);
    #else
        Wire.send(reg);
    #endif
    Wire.endTransmission();

    delay(1);

    Wire.beginTransmission(inaAddress);
    Wire.requestFrom(inaAddress, 2);
    while(!Wire.available()) {};
    #if ARDUINO >= 100
        uint8_t vha = Wire.read();
        uint8_t vla = Wire.read();
    #else
        uint8_t vha = Wire.receive();
        uint8_t vla = Wire.receive();
    #endif;
    Wire.endTransmission();

    value = vha << 8 | vla;

    return value;
}

void INA226::writeRegister16(uint8_t reg, uint16_t val)
{
    uint8_t vla;
    vla = (uint8_t)val;
    val >>= 8;

    Wire.beginTransmission(inaAddress);
    #if ARDUINO >= 100
        Wire.write(reg);
        Wire.write((uint8_t)val);
        Wire.write(vla);
    #else
        Wire.send(reg);
        Wire.send((uint8_t)val);
        Wire.send(vla);
    #endif
    Wire.endTransmission();
}