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### BM 71 Precise Temperature Sensor

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sabau
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# BM 71 Precise Temperature Sensor

Hello,

I have managed to read our the raw value of the temperature measurement.
Next step is to convert it in degrees. I have been unable to fine any specification that explains how to do that.

Can someone help me out ? Is there specifiaction that explains this ?

ric
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Re: BM 71 Precise Temperature Sensor 2021/01/13 22:57:35 (permalink)
4 (1)
That gives raw counts for -20C and +70C.
I assume it is meant to be a linear relationship.

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sabau
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Re: BM 71 Precise Temperature Sensor 2021/01/14 00:22:25 (permalink)
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Yes i did but even so it still seems a bit off and normally temperature sensors do have a conversion formula from measured value to degrees. These formulas vary so yeah .. it is not that straightforward.
blue_led
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Re: BM 71 Precise Temperature Sensor 2021/01/14 00:51:47 (permalink)
2.5 (2)
-20°C = 1387
...
+70°C = 2448
ric
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Re: BM 71 Precise Temperature Sensor 2021/01/14 01:05:53 (permalink)
4 (1)
sabau
Yes i did but even so it still seems a bit off

What is "a bit off" ?
The datasheet only promises 3 degree accuracy.

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sabau
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Re: BM 71 Precise Temperature Sensor 2021/01/14 01:10:24 (permalink)
4.5 (2)
room temperature 21 degrees, measured temperature 15 degrees at best :), and i am afraid the higher the temperature goes, the higher the discrepancy (just an assumption).

Either way since microchip says it gives 3° precision over the [-20°,70°] range i assume it was somewhat tested over this range and a conversion formula or lookup table or whatever was used.
post edited by sabau - 2021/01/14 01:26:51
blue_led
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Re: BM 71 Precise Temperature Sensor 2021/01/14 11:42:15 (permalink)
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sabau
room temperature 21 degrees, measured temperature 15 degrees at best :), and i am afraid the higher the temperature goes, the higher the discrepancy (just an assumption).
Either way since microchip says it gives 3° precision over the [-20°,70°] range i assume it was somewhat tested over this range and a conversion formula or lookup table or whatever was used.

I bet the mchp doesn't bother to test the temperature sensor, that it will increase production price. it is marginal to them. it is there only for customer convenience.
that module is not a temperature sensor, even one with bad accuracy.
or is  by design, inside a case temperature is higher than outside.

__joke()
you have a chip from edge of wafer.
or is  by design, inside a housing temperature is higher than outside.
post edited by blue_led - 2021/01/14 12:06:41