INA219.cpp

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/*
 * This file is part of the DUDS project. It is subject to the BSD-style
 * license terms in the LICENSE file found in the top-level directory of this
 * distribution and at https://github.com/jjackowski/duds/blob/master/LICENSE.
 * No part of DUDS, including this file, may be copied, modified, propagated,
 * or distributed except according to the terms contained in the LICENSE file.
 *
 * Copyright (C) 2017  Jeff Jackowski
 */
#include <duds/hardware/devices/instruments/INA219.hpp>

namespace duds { namespace hardware { namespace devices { namespace instruments {

INA219::INA219(
    std::unique_ptr<duds::hardware::interface::Smbus> &c,
    double sr
) : shunt(sr) {
    // reset device
    c->transmitWordBe(0, 0x8000);
    c->transmitWordBe(0, 0x1FFF);  // 128 samples, 16v bus
    // only take the communicator if no exception is thrown
    com = std::move(c);
}

INA219::~INA219() {
    if (com) {
        // put device to sleep; set widest ranges in case that is good
        com->transmitWordBe(0, 0x3998);
    }
}

duds::data::Quantity INA219::maxCurrent() const {
    return duds::data::Quantity(0.32 / shunt, duds::data::units::Ampere);
}

duds::data::Quantity INA219::shuntResistance() const {
    return duds::data::Quantity(shunt, duds::data::units::Ohm);
}

duds::data::Quantity INA219::shuntVoltage() const {
    return duds::data::Quantity(((double)shuntV) * 1e-5, duds::data::units::Volt);
}

duds::data::Quantity INA219::busVoltage() const {
    return duds::data::Quantity(((double)busV) * 4e-3, duds::data::units::Volt);
}

duds::data::Quantity INA219::busCurrent() const {
    return shuntVoltage() / shuntResistance();
}

duds::data::Quantity INA219::busPower() const {
    return busVoltage() * busCurrent();
}

void INA219::sample() {
    shuntV = com->receiveWordBe(1);
    busV = (std::int16_t)(com->receiveWordBe(2)) >> 3;
}

} } } }