Olimex Support Forum

Microcontrollers => PIC => Topic started by: toozie21 on March 13, 2014, 01:53:47 am

Title: What thermistor is on the PIC-MAXI-WEB?
Post by: toozie21 on March 13, 2014, 01:53:47 am
I am looking to pick up the PIC-MAXI-WEB, but I can't figure out what thermistor is on there (I want to make sure it will work for my application).  The schematic doesn't call out a part number for me to look up a datasheet for.  Does anyone know what part that is?
Title: Re: What thermistor is on the PIC-MAXI-WEB?
Post by: LubOlimex on March 18, 2014, 10:01:17 am
It is NTC103 10k. The B parameter is 4100.

There is plenty of info about such thermistors if you search the web. The part of the code responsible for the measurement is the blow one:

HTTPPrint_temp(void)

...
   
    r = ((1024.0*10000.0)/(float)tmp)-10000.0;
    // B parameter equation - B = 4100
    temperature = 4100.0/log(r/0.0111182) - 273.15;

    itoa(temperature, TempString);

...
}


We had to improvise with the B parameter equation a bit (http://en.wikipedia.org/wiki/Thermistor) because the board was using too much memory initially.

Best regards,
Lub/OLIMEX
Title: Re: What thermistor is on the PIC-MAXI-WEB?
Post by: toozie21 on March 20, 2014, 02:55:14 am
Awesome, thanks so much!