12 years, 10 months ago.

Without trying it myself, I am pretty sure you are getting a warning on that code that you are doing something with your printf that you shouldnt be doing: you are printing a float with the '%d' command. Printing floats is done with %f, so replacing that should fix it.

And afaik %s is only meant to be used with an array of chars, not with actual strings, so that doesn't work. Generally you really don't want to be using strings anyway, strings and their function consume enormous amounts of RAM memory, so better stick to char arrays.

12 years, 10 months ago.

According to the datasheet the temperature in degrees celsius is:

temp = 0.0512 * v_out - 20.5128

With v_out the sensor outputvalue in mV.

The mbed AnalogIn will give you a value between 0 and 1.0 for input voltages between 0V and 3V3. That means you have to multiply the AnalogIn value by 3300 to get the voltage in mV.

Something like this should work:

float tempSensor::getCurrentTempValue()
{
    float v_out;
    float temp;
    
//dont need this delay when the probe is permanently powered
    printf("Temp Probe Warming Up!\n");
 
    wait(2);
    printf("2 seconds has passed!\n");

    v_out = _resTemp.read();
//    v_out*=.0048;
//    v_out*=1000;
//    temp= 0.0512 * v_out -20.5128;

    temp = 0.0512 * (v_out * 3300) - 20.5128;
    
    printf("ResTemp: %f\n", temp);  // use %f for float instead of %d 
    
//    ostringstream ostr; //output string stream
//    ostr << temp; //use the string stream just like cout,
    //except the stream prints not to stdout but to a string.
 
//    string theNumberString = ostr.str(); //the str() function of the stream 
    //returns the string.
    
//    printf("ResTemp: %s\n", theNumberString);
//    _msExt.sendCommand("resTemp: ", theNumberString);
    
    return temp;
}

Note that you may want to measure several times and average to cancel noise.

You still need to fix the string part. Recommend you use char arrays as suggested by Erik. The sprintf will convert floats to a char string.