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LACTIC
LACTIC
Associate III
March 9, 2019
Question

Is stm32 micro-controls are capable to calculate Natural Logarithm ?

  • March 9, 2019
  • 2 replies
  • 2513 views

I am using Thermistor (NTC Type ) as temperature sensor .

So to calculate the temperature from adc value of STM32 I am using this formula(taken from this site :- https://www.jameco.com/jameco/workshop/techtip/temperature-measurement-ntc-thermistors.html)

1/T = 1/T0 + 1/B * ln( ( adcMax / adcVal ) – 1 )

where :-

T0= 298.15 K

B=3345.80 K

I am using Board 6-Bit adc .

So I want ask that can I use above formula in my program, because I am confuse that controller can calculate "ln (Natural Logarithm) ".

    This topic has been closed for replies.

    2 replies

    saiteja
    saiteja
    Associate III
    March 9, 2019

    Interface temperature sensor with any of the adc pin in controller, from pin read the value

    sysTemperature = HAL_ADC_GetValue(&hadc1); 

    sysTemp_inmV = ((float)sysTemperature/4096.0) * 3300; //ref = 3.3

    sysTemp_inCel = sysTemp_inmV/10

    LACTIC
    LACTICAuthor
    Associate III
    March 9, 2019

    Thanks.

    Here 12bit adc enable ?

    Because 4096 is value 2^12.

    waclawek.jan
    waclawek.jan
    Super User
    March 9, 2019

    Following functions calculate the natural logarithm (base e):

    #include <math.h>

    double log(double x);

    float logf(float x);

    long double logl(long double x);

    You may also try to avoid the log calculation by tabulating the function at a suitable step and linearly interpolate between the steps; or by fittingthe function by polynomial.

    JW

    LACTIC
    LACTICAuthor
    Associate III
    March 11, 2019

    OK

    Amel NASRI
    Amel NASRI
    ST Technical Moderator
    March 11, 2019

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