STM32F205 temperature sensor problems

tfk · ‎2011-06-24

Posted on June 24, 2011 at 15:06

Hi everybody,

I'm having some trouble with the STM32F205 temperature sensor.

I'm using the algorithm from section 10.10 in the reference manual. {(V25 � VSENSE) / Avg_Slope} + 25

I'm using the following algorithm to convert the ADC value to a voltage value from the temperature sensor ADC channel (ch 16):

ADCConvertedValue*3.3/4096;

When I'm heating up the chip the ADCConvertedValue increases resulting in a greater voltage value, that results in lower temperature as a higher VSENSE value will subtract more from V25.

Does anyone have the same problem ?

Best Regards

Tord

#not-that-complicated #vsense-temperature-sensor #adc-dma #stm32f205-temperature

pedro23 · ‎2016-01-18

Posted on January 18, 2016 at 11:17

The conversion formula is wrong... if you check this:

http://www.st.com/web/en/resource/technical/document/datasheet/CD00161566.pdf

(Seccion 5.3.19)

//{(V25 - VSENSE) / Avg_Slope} + 25

//V25 = 1.43 , avg_slope = 4.3mv/CÂº

Avg_Slope(1) Average slope 4.0 4.3 4.6 mV/Â°C

V25(1) Voltage at 25 Â°C 1.34 1.43 1.52 V

avg slope is 4.3 mv/c

and voltage at 25Âº is 1.43...

if your vref is 3.3v

AverageADValue is the value of your internal temperature sensor AD

unsigned int adcVolt = 0;

signed int diffVolt = 0;

signed int temp1 = 0;

adcVolt = AverageADValue*33000/4096;

diffVolt = adcVolt - 14300; // (1.43v at 25Âº & vref=3.3)

temp1 = diffVolt / 43; //0.0043 v / cÂº

temp1+=250; //Since it is in degree decimals

Maybe the above code conversion is old. I Used it previously but since temperatures are always around 25 degrees here it didnt fail too much.

But I change to these values because they are the right based on datasheets.

Best regards.