sendCommand failure? - Githubissues

I'm not sure whether the sendCommand approach works as intended.

If you do a

while (_hs->available()) { _hs->read(); }

it assumes that the sensor instantly starts to send after sending the command and does it continuously instantly and so fast, that the µC always has data to poll away.

I think a better approach would be to just count the 9 bytes and encapsulate it with a timeout. (I never assume that I get all the data due to all sorts of things that could happen...)

Reason I mention is that I implemented a new function

MHZ19_RESULT MHZ19::rawdataread(byte (*cmd)[9]) {
    memset(*cmd, 0, 9);

    if (_hs)
    {
        _hs->readBytes(*cmd, 9);
    }
    else
    {
        _ss->readBytes(*cmd, 9);
    }

    byte crc = calcCRC(*cmd);

    MHZ19_RESULT _result = MHZ19_RESULT_OK;
    if ((*cmd)[0] != 0xFF)
        _result = MHZ19_RESULT_ERR_FB;
    if ((*cmd)[8] != crc)
        _result = MHZ19_RESULT_ERR_CRC;

    return _result;
}

and this happily reads the returned data from sendCommand.

In the end I think there needs to be some sort of redesign, whether sendCommand eats the returned data or allows to get it via rawdataread. For my simple solution I removed the reading and let sendCommand only do a send.

strange-v / MHZ19

sendCommand failure? #2