Calculating temperature

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Sir. \ Madam,

 

What's the equation in calculating current temperature from internal temperature sensor input to ADCA channel 0 result register ?

 

From the current value in ADCACH0RES = 0x0942 may I calculate the current temperature as of :

 

current temperature = ( ADCACH0RES current value - 200 ) / ( ( PRODSIGNATURES_TEMPSENSE - 200 ) / 85 ) = ( 0x0942 -200 ) / ( ( 0x0A80 - 200 ) / 85 ) =  ( 2370 - 200 ) / ( ( 2688 -200 ) / 85 ) = 74 °C  ?

 

My office AC sets at 22 °C  and my DUT is in open air.

 

Sincerelym,

Liu Wang

 

ADCA channel 0 result register value = 0x0942:

ADCA temperature sensor calibration value = 0x0A80:

 

AVR ADC Spec: 

 

Last Edited: Fri. Jun 9, 2017 - 03:42 AM
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Please DO NOT put a long title to your thread! I have cut it down to 2 words, you can explain what you need in the BODY of the text not the header.

John Samperi

Ampertronics Pty. Ltd.

www.ampertronics.com.au

* Electronic Design * Custom Products * Contract Assembly

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liu wang wrote:

What's the equation in calculating current temperature from internal temperature sensor input to ADCA channel 0 result register ?

 

From the current value in ADCACH0RES = 0x0942 may I calculate the current temperature as of :

current temperature = ( ADCACH0RES current value - 200 ) / ( ( PRODSIGNATURES_TEMPSENSE - 200 ) / 85 ) = ( 0x0942 -200 ) / ( ( 0x0A80 - 200 ) / 85 ) =  ( 2370 - 200 ) / ( ( 2688 -200 ) / 85 ) = 74 °C  ?

My office AC sets at 22 °C  and my DUT is in open air.

 

From your post #1, "An approximate linear line can be made from 0°K ..."

0°K is not 0°C.

 

Using your equation from post#1, but with 358°K instead of 85°C results in:

    (2170/2488) * 358°K = 312.24°K

    312°K - 273°K = 39°C (± 15°C)

 

Edit:

   Not ±15°C but (2170/2488) * 15 = ±13°C for the example above.

 

Last Edited: Fri. Jun 9, 2017 - 05:04 AM