Possible problem with signed/unsigned char

[lynxzp]

When I moved excising project on Arduino Due, I got compiler warning

comparison (celsius < -55) is always false due to limited range of data type

1 Because char is unsigned by default on ArduinoDdue, forum discussion. Maybe char need replace with signed char?

2 But also I noticed that this signed value later convert in unsigned before sending on device. Don't know is it right or not.

void DallasTemperature::setHighAlarmTemp(const uint8_t* deviceAddress, char celsius){
    // make sure the alarm temperature is within the device's range
    if (celsius > 125) celsius = 125;
    else if (celsius < -55) celsius = -55;

    ScratchPad scratchPad;
    if (isConnected(deviceAddress, scratchPad)){
        scratchPad[HIGH_ALARM_TEMP] = (uint8_t)celsius;
        writeScratchPad(deviceAddress, scratchPad);
    }
}

[RobTillaart]

Good find!
(un)(signed) char should not be used as the parameter is not text.
I propose to use int8_t as the parameter is an integer type.

The char type must be replaced by int8_t in setLowAlarmTemp(), getLowAlarmTemp(), getHighAlarmTemp(), in alarmSearchJunction;, and intern in alarmSearch() and hasAlarm()

I will try to make a pull request for this soon.