MCP9808.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) 2020  Jeff Jackowski
 */
#include <duds/hardware/devices/instruments/MCP9808.hpp>
#include <duds/hardware/devices/DeviceErrors.hpp>
#include <duds/hardware/interface/SmbusErrors.hpp>

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

MCP9808::MCP9808(std::unique_ptr<duds::hardware::interface::Smbus> &c) {
    // attempt to confirm that this is a MCP9808
    std::int16_t chk = c->receiveWordBe(6);
    if (chk != 0x54) {
        // wrong response
        DUDS_THROW_EXCEPTION(DeviceMisidentified() <<
            duds::hardware::interface::SmbusDeviceAddr(com->address())
        );
    }
    chk = c->receiveWordBe(7);
    if ((chk & 0xFF00) != 0x400) {
        // wrong response
        DUDS_THROW_EXCEPTION(DeviceMisidentified() <<
            duds::hardware::interface::SmbusDeviceAddr(com->address())
        );
    }
    // keep revision
    rev = chk & 0xFF;
    // get the resolution
    res = c->receiveByte(8);
    // get the current configuration
    config = c->receiveWordBe(1);
    // only take the communicator if no exception is thrown
    com = std::move(c);
}

MCP9808::~MCP9808() {
    suspend();
}

void MCP9808::start() {
    config &= 0x6FF;
    com->transmitWordBe(1, config);
}

void MCP9808::suspend() {
    config |= 0x100;
    com->transmitWordBe(1, config);
}

void MCP9808::resolution(Resolution r) {
    res = r & 3;
    com->transmitByte(8, res);
}

double MCP9808::resolutionDegrees() const {
    switch (res) {
        case Half:
            return 0.5;
        case Quarter:
            return 0.25;
        case Eighth:
            return 0.125;
        case Sixteenth:
            return 0.0625;
    }
    // should never happen
    return 0;
}

void MCP9808::sample() {
    std::int16_t samp = com->receiveWordBe(5);
    temp = ((double)duds::general::SignExtend<13>(samp)) / 16.0 + 273.15;
}

duds::data::Quantity MCP9808::temperature() const {
    return duds::data::Quantity(temp, duds::data::units::Kelvin);
}

} } } }