Program Listing for File mcp3x0x.cpp

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#include "mcp3x0x/mcp3x0x.hh"

using iplo::MCP3X0X;

std::int16_t MCP3X0X::readAnalogValue(std::uint8_t channel, bool single) {
    if (channel > _channels) {
        return 0;
    }

    std::uint8_t txData[3] = {0, 0, 0};
    std::uint8_t bytes = buildRequest(channel, single, txData);
    std::uint8_t rxData[3];

    const auto bytesTransferred = _spi.xfer(txData, sizeof(txData), rxData, sizeof(rxData));
    if (bytesTransferred < 0 || bytesTransferred != bytes) {
        return -1;
    }

    if (bytes == 2) {
        return (256 * rxData[0] + rxData[1]) & _maxValue;
    }

    return (256 * rxData[1] + rxData[2]) & _maxValue;
}

MCP3X0X::MCP3X0X(SPI& spi) : _spi(spi) {}

std::int16_t MCP3X0X::analogRead(std::uint8_t channel) {
    if (channel >= _channels) {
        return 0;
    }

    return readAnalogValue(channel, true);
}

std::int16_t MCP3X0X::differentialRead(std::uint8_t channel) {
    if (channel >= _channels) {
        return 0;
    }

    return readAnalogValue(channel, false);
}

std::int16_t MCP3X0X::deltaRead(std::uint8_t channel) {
    if (channel >= _channels)
        return 0;

    const auto firstValue = differentialRead(channel & 0xFE);
    const auto secondValue = (firstValue > 0) ? 0 : differentialRead(channel | 0x01);

    if (channel & 0x01) {
        return secondValue - firstValue;
    }

    return firstValue - secondValue;
}

std::uint8_t MCP3X0X::channels() {
    return _channels;
}